90 files changed, 1402 insertions, 331 deletions

diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 7b9fbe6b8..889ada401 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -124,10 +124,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
-    - name: Install Rust toolchain (beta)
+    - name: Install Rust toolchain
       uses: actions-rs/toolchain@v1
       with:
-        toolchain: beta
+        toolchain: stable
         target: aarch64-apple-darwin
         profile: minimal
         override: true
diff --git a/Cargo.lock b/Cargo.lock
index 1aa0c072d..4aaee3ab1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -386,11 +386,11 @@ dependencies = [
 
 [[package]]
 name = "expect-test"
-version = "1.0.2"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eab78d4c727fa879de40951ffc01ed781a231b28786b19d6bfbdc0d1ec92eb3e"
+checksum = "2300477aab3a378f2ca00a4fbd4dc713654ab7ed790e4017493cb33656280633"
 dependencies = [
- "difference",
+ "dissimilar",
  "once_cell",
 ]
 
diff --git a/crates/assists/src/ast_transform.rs b/crates/assists/src/ast_transform.rs
index da94e9987..4a3ed7783 100644
--- a/crates/assists/src/ast_transform.rs
+++ b/crates/assists/src/ast_transform.rs
@@ -204,7 +204,8 @@ impl<'a> AstTransform<'a> for QualifyPaths<'a> {
             }
             PathResolution::Local(_)
             | PathResolution::TypeParam(_)
-            | PathResolution::SelfType(_) => None,
+            | PathResolution::SelfType(_)
+            | PathResolution::ConstParam(_) => None,
             PathResolution::Macro(_) => None,
             PathResolution::AssocItem(_) => None,
         }
diff --git a/crates/assists/src/handlers/extract_assignment.rs b/crates/assists/src/handlers/extract_assignment.rs
new file mode 100644
index 000000000..ae99598c0
--- /dev/null
+++ b/crates/assists/src/handlers/extract_assignment.rs
@@ -0,0 +1,400 @@
+use syntax::{
+    ast::{self, edit::AstNodeEdit, make},
+    AstNode,
+};
+use test_utils::mark;
+
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId, AssistKind,
+};
+
+// Assist: extract_assignment
+//
+// Extracts variable assigment to outside an if or match statement.
+//
+// ```
+// fn main() {
+//     let mut foo = 6;
+//
+//     if true {
+//         <|>foo = 5;
+//     } else {
+//         foo = 4;
+//     }
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let mut foo = 6;
+//
+//     foo = if true {
+//         5
+//     } else {
+//         4
+//     };
+// }
+// ```
+pub(crate) fn extract_assigment(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let assign_expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
+    let name_expr = if assign_expr.op_kind()? == ast::BinOp::Assignment {
+        assign_expr.lhs()?
+    } else {
+        return None;
+    };
+
+    let (old_stmt, new_stmt) = if let Some(if_expr) = ctx.find_node_at_offset::<ast::IfExpr>() {
+        (
+            ast::Expr::cast(if_expr.syntax().to_owned())?,
+            exprify_if(&if_expr, &ctx.sema, &name_expr)?.indent(if_expr.indent_level()),
+        )
+    } else if let Some(match_expr) = ctx.find_node_at_offset::<ast::MatchExpr>() {
+        (
+            ast::Expr::cast(match_expr.syntax().to_owned())?,
+            exprify_match(&match_expr, &ctx.sema, &name_expr)?,
+        )
+    } else {
+        return None;
+    };
+
+    let expr_stmt = make::expr_stmt(new_stmt);
+
+    acc.add(
+        AssistId("extract_assignment", AssistKind::RefactorExtract),
+        "Extract assignment",
+        old_stmt.syntax().text_range(),
+        move |edit| {
+            edit.replace(old_stmt.syntax().text_range(), format!("{} = {};", name_expr, expr_stmt));
+        },
+    )
+}
+
+fn exprify_match(
+    match_expr: &ast::MatchExpr,
+    sema: &hir::Semantics<ide_db::RootDatabase>,
+    name: &ast::Expr,
+) -> Option<ast::Expr> {
+    let new_arm_list = match_expr
+        .match_arm_list()?
+        .arms()
+        .map(|arm| {
+            if let ast::Expr::BlockExpr(block) = arm.expr()? {
+                let new_block = exprify_block(&block, sema, name)?.indent(block.indent_level());
+                Some(arm.replace_descendant(block, new_block))
+            } else {
+                None
+            }
+        })
+        .collect::<Option<Vec<_>>>()?;
+    let new_arm_list = match_expr
+        .match_arm_list()?
+        .replace_descendants(match_expr.match_arm_list()?.arms().zip(new_arm_list));
+    Some(make::expr_match(match_expr.expr()?, new_arm_list))
+}
+
+fn exprify_if(
+    statement: &ast::IfExpr,
+    sema: &hir::Semantics<ide_db::RootDatabase>,
+    name: &ast::Expr,
+) -> Option<ast::Expr> {
+    let then_branch = exprify_block(&statement.then_branch()?, sema, name)?;
+    let else_branch = match statement.else_branch()? {
+        ast::ElseBranch::Block(ref block) => {
+            ast::ElseBranch::Block(exprify_block(block, sema, name)?)
+        }
+        ast::ElseBranch::IfExpr(expr) => {
+            mark::hit!(test_extract_assigment_chained_if);
+            ast::ElseBranch::IfExpr(ast::IfExpr::cast(
+                exprify_if(&expr, sema, name)?.syntax().to_owned(),
+            )?)
+        }
+    };
+    Some(make::expr_if(statement.condition()?, then_branch, Some(else_branch)))
+}
+
+fn exprify_block(
+    block: &ast::BlockExpr,
+    sema: &hir::Semantics<ide_db::RootDatabase>,
+    name: &ast::Expr,
+) -> Option<ast::BlockExpr> {
+    if block.expr().is_some() {
+        return None;
+    }
+
+    let mut stmts: Vec<_> = block.statements().collect();
+    let stmt = stmts.pop()?;
+
+    if let ast::Stmt::ExprStmt(stmt) = stmt {
+        if let ast::Expr::BinExpr(expr) = stmt.expr()? {
+            if expr.op_kind()? == ast::BinOp::Assignment && is_equivalent(sema, &expr.lhs()?, name)
+            {
+                // The last statement in the block is an assignment to the name we want
+                return Some(make::block_expr(stmts, Some(expr.rhs()?)));
+            }
+        }
+    }
+    None
+}
+
+fn is_equivalent(
+    sema: &hir::Semantics<ide_db::RootDatabase>,
+    expr0: &ast::Expr,
+    expr1: &ast::Expr,
+) -> bool {
+    match (expr0, expr1) {
+        (ast::Expr::FieldExpr(field_expr0), ast::Expr::FieldExpr(field_expr1)) => {
+            mark::hit!(test_extract_assignment_field_assignment);
+            sema.resolve_field(field_expr0) == sema.resolve_field(field_expr1)
+        }
+        (ast::Expr::PathExpr(path0), ast::Expr::PathExpr(path1)) => {
+            let path0 = path0.path();
+            let path1 = path1.path();
+            if let (Some(path0), Some(path1)) = (path0, path1) {
+                sema.resolve_path(&path0) == sema.resolve_path(&path1)
+            } else {
+                false
+            }
+        }
+        _ => false,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    #[test]
+    fn test_extract_assignment_if() {
+        check_assist(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    if true {
+        <|>a = 2;
+    } else {
+        a = 3;
+    }
+}"#,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    a = if true {
+        2
+    } else {
+        3
+    };
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_extract_assignment_match() {
+        check_assist(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    match 1 {
+        1 => {
+            <|>a = 2;
+        },
+        2 => {
+            a = 3;
+        },
+        3 => {
+            a = 4;
+        }
+    }
+}"#,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    a = match 1 {
+        1 => {
+            2
+        },
+        2 => {
+            3
+        },
+        3 => {
+            4
+        }
+    };
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_extract_assignment_not_last_not_applicable() {
+        check_assist_not_applicable(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    if true {
+        <|>a = 2;
+        b = a;
+    } else {
+        a = 3;
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn test_extract_assignment_chained_if() {
+        mark::check!(test_extract_assigment_chained_if);
+        check_assist(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    if true {
+        <|>a = 2;
+    } else if false {
+        a = 3;
+    } else {
+        a = 4;
+    }
+}"#,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    a = if true {
+        2
+    } else if false {
+        3
+    } else {
+        4
+    };
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_extract_assigment_retains_stmts() {
+        check_assist(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    if true {
+        let b = 2;
+        <|>a = 2;
+    } else {
+        let b = 3;
+        a = 3;
+    }
+}"#,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    a = if true {
+        let b = 2;
+        2
+    } else {
+        let b = 3;
+        3
+    };
+}"#,
+        )
+    }
+
+    #[test]
+    fn extract_assignment_let_stmt_not_applicable() {
+        check_assist_not_applicable(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    let b = if true {
+        <|>a = 2
+    } else {
+        a = 3
+    };
+}"#,
+        )
+    }
+
+    #[test]
+    fn extract_assignment_if_missing_assigment_not_applicable() {
+        check_assist_not_applicable(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    if true {
+        <|>a = 2;
+    } else {}
+}"#,
+        )
+    }
+
+    #[test]
+    fn extract_assignment_match_missing_assigment_not_applicable() {
+        check_assist_not_applicable(
+            extract_assigment,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    match 1 {
+        1 => {
+            <|>a = 2;
+        },
+        2 => {
+            a = 3;
+        },
+        3 => {},
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn test_extract_assignment_field_assignment() {
+        mark::check!(test_extract_assignment_field_assignment);
+        check_assist(
+            extract_assigment,
+            r#"
+struct A(usize);
+
+fn foo() {
+    let mut a = A(1);
+
+    if true {
+        <|>a.0 = 2;
+    } else {
+        a.0 = 3;
+    }
+}"#,
+            r#"
+struct A(usize);
+
+fn foo() {
+    let mut a = A(1);
+
+    a.0 = if true {
+        2
+    } else {
+        3
+    };
+}"#,
+        )
+    }
+}
diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index cb60a3128..f9a62b9fa 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -196,7 +196,7 @@ fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::Variant) -> Optio
     let path = mod_path_to_ast(&module.find_use_path(db, ModuleDef::from(var))?);
 
     // FIXME: use HIR for this; it doesn't currently expose struct vs. tuple vs. unit variants though
-    let pat: ast::Pat = match var.source(db).value.kind() {
+    let pat: ast::Pat = match var.source(db)?.value.kind() {
         ast::StructKind::Tuple(field_list) => {
             let pats = iter::repeat(make::wildcard_pat().into()).take(field_list.fields().count());
             make::tuple_struct_pat(path, pats).into()
diff --git a/crates/assists/src/handlers/fix_visibility.rs b/crates/assists/src/handlers/fix_visibility.rs
index 8558a8ff0..de1e8f0bf 100644
--- a/crates/assists/src/handlers/fix_visibility.rs
+++ b/crates/assists/src/handlers/fix_visibility.rs
@@ -97,7 +97,8 @@ fn add_vis_to_referenced_record_field(acc: &mut Assists, ctx: &AssistContext) ->
     let parent_name = parent.name(ctx.db());
     let target_module = parent.module(ctx.db());
 
-    let in_file_source = record_field_def.source(ctx.db());
+    #[allow(deprecated)]
+    let in_file_source = record_field_def.source(ctx.db())?;
     let (offset, current_visibility, target) = match in_file_source.value {
         hir::FieldSource::Named(it) => {
             let s = it.syntax();
@@ -145,53 +146,53 @@ fn target_data_for_def(
     fn offset_target_and_file_id<S, Ast>(
         db: &dyn HirDatabase,
         x: S,
-    ) -> (TextSize, Option<ast::Visibility>, TextRange, FileId)
+    ) -> Option<(TextSize, Option<ast::Visibility>, TextRange, FileId)>
     where
         S: HasSource<Ast = Ast>,
         Ast: AstNode + ast::VisibilityOwner,
     {
-        let source = x.source(db);
+        let source = x.source(db)?;
         let in_file_syntax = source.syntax();
         let file_id = in_file_syntax.file_id;
         let syntax = in_file_syntax.value;
         let current_visibility = source.value.visibility();
-        (
+        Some((
             vis_offset(syntax),
             current_visibility,
             syntax.text_range(),
             file_id.original_file(db.upcast()),
-        )
+        ))
     }
 
     let target_name;
     let (offset, current_visibility, target, target_file) = match def {
         hir::ModuleDef::Function(f) => {
             target_name = Some(f.name(db));
-            offset_target_and_file_id(db, f)
+            offset_target_and_file_id(db, f)?
         }
         hir::ModuleDef::Adt(adt) => {
             target_name = Some(adt.name(db));
             match adt {
-                hir::Adt::Struct(s) => offset_target_and_file_id(db, s),
-                hir::Adt::Union(u) => offset_target_and_file_id(db, u),
-                hir::Adt::Enum(e) => offset_target_and_file_id(db, e),
+                hir::Adt::Struct(s) => offset_target_and_file_id(db, s)?,
+                hir::Adt::Union(u) => offset_target_and_file_id(db, u)?,
+                hir::Adt::Enum(e) => offset_target_and_file_id(db, e)?,
             }
         }
         hir::ModuleDef::Const(c) => {
             target_name = c.name(db);
-            offset_target_and_file_id(db, c)
+            offset_target_and_file_id(db, c)?
         }
         hir::ModuleDef::Static(s) => {
             target_name = s.name(db);
-            offset_target_and_file_id(db, s)
+            offset_target_and_file_id(db, s)?
         }
         hir::ModuleDef::Trait(t) => {
             target_name = Some(t.name(db));
-            offset_target_and_file_id(db, t)
+            offset_target_and_file_id(db, t)?
         }
         hir::ModuleDef::TypeAlias(t) => {
             target_name = Some(t.name(db));
-            offset_target_and_file_id(db, t)
+            offset_target_and_file_id(db, t)?
         }
         hir::ModuleDef::Module(m) => {
             target_name = m.name(db);
diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index fdec886e9..212464f85 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -116,6 +116,7 @@ mod handlers {
     mod convert_integer_literal;
     mod early_return;
     mod expand_glob_import;
+    mod extract_assignment;
     mod extract_module_to_file;
     mod extract_struct_from_enum_variant;
     mod extract_variable;
@@ -167,6 +168,7 @@ mod handlers {
             convert_integer_literal::convert_integer_literal,
             early_return::convert_to_guarded_return,
             expand_glob_import::expand_glob_import,
+            extract_assignment::extract_assigment,
             extract_module_to_file::extract_module_to_file,
             extract_struct_from_enum_variant::extract_struct_from_enum_variant,
             extract_variable::extract_variable,
diff --git a/crates/assists/src/tests/generated.rs b/crates/assists/src/tests/generated.rs
index d3dfe24e7..b91a816e8 100644
--- a/crates/assists/src/tests/generated.rs
+++ b/crates/assists/src/tests/generated.rs
@@ -238,6 +238,35 @@ fn qux(bar: Bar, baz: Baz) {}
 }
 
 #[test]
+fn doctest_extract_assignment() {
+    check_doc_test(
+        "extract_assignment",
+        r#####"
+fn main() {
+    let mut foo = 6;
+
+    if true {
+        <|>foo = 5;
+    } else {
+        foo = 4;
+    }
+}
+"#####,
+        r#####"
+fn main() {
+    let mut foo = 6;
+
+    foo = if true {
+        5
+    } else {
+        4
+    };
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_extract_module_to_file() {
     check_doc_test(
         "extract_module_to_file",
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index d41084b59..b05596446 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -94,14 +94,18 @@ pub fn filter_assoc_items(
             ast::AssocItem::MacroCall(_) => None,
         }
         .is_some()
-    };
+    }
 
     items
         .iter()
-        .map(|i| match i {
-            hir::AssocItem::Function(i) => ast::AssocItem::Fn(i.source(db).value),
-            hir::AssocItem::TypeAlias(i) => ast::AssocItem::TypeAlias(i.source(db).value),
-            hir::AssocItem::Const(i) => ast::AssocItem::Const(i.source(db).value),
+        // Note: This throws away items with no source.
+        .filter_map(|i| {
+            let item = match i {
+                hir::AssocItem::Function(i) => ast::AssocItem::Fn(i.source(db)?.value),
+                hir::AssocItem::TypeAlias(i) => ast::AssocItem::TypeAlias(i.source(db)?.value),
+                hir::AssocItem::Const(i) => ast::AssocItem::Const(i.source(db)?.value),
+            };
+            Some(item)
         })
         .filter(has_def_name)
         .filter(|it| match it {
diff --git a/crates/base_db/src/input.rs b/crates/base_db/src/input.rs
index 9567bcc42..2dd8fbe67 100644
--- a/crates/base_db/src/input.rs
+++ b/crates/base_db/src/input.rs
@@ -190,10 +190,11 @@ pub struct CrateData {
     pub proc_macro: Vec<ProcMacro>,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Edition {
-    Edition2018,
     Edition2015,
+    Edition2018,
+    Edition2021,
 }
 
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
@@ -393,6 +394,7 @@ impl FromStr for Edition {
         let res = match s {
             "2015" => Edition::Edition2015,
             "2018" => Edition::Edition2018,
+            "2021" => Edition::Edition2021,
             _ => return Err(ParseEditionError { invalid_input: s.to_string() }),
         };
         Ok(res)
@@ -404,6 +406,7 @@ impl fmt::Display for Edition {
         f.write_str(match self {
             Edition::Edition2015 => "2015",
             Edition::Edition2018 => "2018",
+            Edition::Edition2021 => "2021",
         })
     }
 }
diff --git a/crates/cfg/Cargo.toml b/crates/cfg/Cargo.toml
index c68e391c1..73247d130 100644
--- a/crates/cfg/Cargo.toml
+++ b/crates/cfg/Cargo.toml
@@ -17,4 +17,4 @@ tt = { path = "../tt", version = "0.0.0" }
 [dev-dependencies]
 mbe = { path = "../mbe" }
 syntax = { path = "../syntax" }
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/completion/Cargo.toml b/crates/completion/Cargo.toml
index 78e93e78e..99a1bdd54 100644
--- a/crates/completion/Cargo.toml
+++ b/crates/completion/Cargo.toml
@@ -28,4 +28,4 @@ test_utils = { path = "../test_utils", version = "0.0.0" }
 hir = { path = "../hir", version = "0.0.0" }
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/completion/src/completions.rs b/crates/completion/src/completions.rs
index d9fe13485..00c9e76f0 100644
--- a/crates/completion/src/completions.rs
+++ b/crates/completion/src/completions.rs
@@ -106,8 +106,9 @@ impl Completions {
         func: hir::Function,
         local_name: Option<String>,
     ) {
-        let item = render_fn(RenderContext::new(ctx), None, local_name, func);
-        self.add(item)
+        if let Some(item) = render_fn(RenderContext::new(ctx), None, local_name, func) {
+            self.add(item)
+        }
     }
 
     pub(crate) fn add_variant_pat(
diff --git a/crates/completion/src/completions/record.rs b/crates/completion/src/completions/record.rs
index 91bf4a8ad..e58b9a274 100644
--- a/crates/completion/src/completions/record.rs
+++ b/crates/completion/src/completions/record.rs
@@ -20,13 +20,17 @@ pub(crate) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) ->
 
             let missing_fields = ctx.sema.record_literal_missing_fields(record_lit);
             if impl_default_trait && !missing_fields.is_empty() {
+                let completion_text = "..Default::default()";
+                let completion_text = completion_text
+                    .strip_prefix(ctx.token.to_string().as_str())
+                    .unwrap_or(completion_text);
                 acc.add(
                     CompletionItem::new(
                         CompletionKind::Snippet,
                         ctx.source_range(),
                         "..Default::default()",
                     )
-                    .insert_text("..Default::default()")
+                    .insert_text(completion_text)
                     .kind(CompletionItemKind::Field)
                     .build(),
                 );
@@ -48,7 +52,10 @@ mod tests {
     use expect_test::{expect, Expect};
     use ide_db::helpers::FamousDefs;
 
-    use crate::{test_utils::completion_list, CompletionKind};
+    use crate::{
+        test_utils::{self, completion_list},
+        CompletionKind,
+    };
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Reference);
@@ -63,6 +70,18 @@ mod tests {
         expect.assert_eq(&actual);
     }
 
+    fn check_edit(what: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
+        test_utils::check_edit(
+            what,
+            &format!(
+                "//- /main.rs crate:main deps:core{}\n{}",
+                ra_fixture_before,
+                FamousDefs::FIXTURE,
+            ),
+            &(ra_fixture_after.to_owned() + "\n"),
+        );
+    }
+
     #[test]
     fn test_record_literal_field_default() {
         let test_code = r#"
@@ -102,6 +121,51 @@ fn process(f: S) {
     }
 
     #[test]
+    fn test_record_literal_field_default_completion() {
+        check_edit(
+            "..Default::default()",
+            r#"
+struct S { foo: u32, bar: usize }
+
+impl core::default::Default for S {
+    fn default() -> Self {
+        S {
+            foo: 0,
+            bar: 0,
+        }
+    }
+}
+
+fn process(f: S) {
+    let other = S {
+        foo: 5,
+        .<|>
+    };
+}
+"#,
+            r#"
+struct S { foo: u32, bar: usize }
+
+impl core::default::Default for S {
+    fn default() -> Self {
+        S {
+            foo: 0,
+            bar: 0,
+        }
+    }
+}
+
+fn process(f: S) {
+    let other = S {
+        foo: 5,
+        ..Default::default()
+    };
+}
+"#,
+        );
+    }
+
+    #[test]
     fn test_record_literal_field_without_default() {
         let test_code = r#"
 struct S { foo: u32, bar: usize }
diff --git a/crates/completion/src/completions/trait_impl.rs b/crates/completion/src/completions/trait_impl.rs
index c4e0d0669..54bb897e9 100644
--- a/crates/completion/src/completions/trait_impl.rs
+++ b/crates/completion/src/completions/trait_impl.rs
@@ -156,19 +156,21 @@ fn add_function_impl(
     };
     let range = TextRange::new(fn_def_node.text_range().start(), ctx.source_range().end());
 
-    let function_decl = function_declaration(&func.source(ctx.db).value);
-    match ctx.config.snippet_cap {
-        Some(cap) => {
-            let snippet = format!("{} {{\n    $0\n}}", function_decl);
-            builder.snippet_edit(cap, TextEdit::replace(range, snippet))
-        }
-        None => {
-            let header = format!("{} {{", function_decl);
-            builder.text_edit(TextEdit::replace(range, header))
+    if let Some(src) = func.source(ctx.db) {
+        let function_decl = function_declaration(&src.value);
+        match ctx.config.snippet_cap {
+            Some(cap) => {
+                let snippet = format!("{} {{\n    $0\n}}", function_decl);
+                builder.snippet_edit(cap, TextEdit::replace(range, snippet))
+            }
+            None => {
+                let header = format!("{} {{", function_decl);
+                builder.text_edit(TextEdit::replace(range, header))
+            }
         }
+        .kind(completion_kind)
+        .add_to(acc);
     }
-    .kind(completion_kind)
-    .add_to(acc);
 }
 
 fn add_type_alias_impl(
@@ -200,16 +202,19 @@ fn add_const_impl(
     let const_name = const_.name(ctx.db).map(|n| n.to_string());
 
     if let Some(const_name) = const_name {
-        let snippet = make_const_compl_syntax(&const_.source(ctx.db).value);
-
-        let range = TextRange::new(const_def_node.text_range().start(), ctx.source_range().end());
-
-        CompletionItem::new(CompletionKind::Magic, ctx.source_range(), snippet.clone())
-            .text_edit(TextEdit::replace(range, snippet))
-            .lookup_by(const_name)
-            .kind(CompletionItemKind::Const)
-            .set_documentation(const_.docs(ctx.db))
-            .add_to(acc);
+        if let Some(source) = const_.source(ctx.db) {
+            let snippet = make_const_compl_syntax(&source.value);
+
+            let range =
+                TextRange::new(const_def_node.text_range().start(), ctx.source_range().end());
+
+            CompletionItem::new(CompletionKind::Magic, ctx.source_range(), snippet.clone())
+                .text_edit(TextEdit::replace(range, snippet))
+                .lookup_by(const_name)
+                .kind(CompletionItemKind::Const)
+                .set_documentation(const_.docs(ctx.db))
+                .add_to(acc);
+        }
     }
 }
 
diff --git a/crates/completion/src/render.rs b/crates/completion/src/render.rs
index 1ba7201a1..ac0b2a513 100644
--- a/crates/completion/src/render.rs
+++ b/crates/completion/src/render.rs
@@ -157,8 +157,7 @@ impl<'a> Render<'a> {
 
         let kind = match resolution {
             ScopeDef::ModuleDef(Function(func)) => {
-                let item = render_fn(self.ctx, import_to_add, Some(local_name), *func);
-                return Some(item);
+                return render_fn(self.ctx, import_to_add, Some(local_name), *func);
             }
             ScopeDef::ModuleDef(Variant(_))
                 if self.ctx.completion.is_pat_binding_or_const
diff --git a/crates/completion/src/render/const_.rs b/crates/completion/src/render/const_.rs
index 039bdabc0..ce924f309 100644
--- a/crates/completion/src/render/const_.rs
+++ b/crates/completion/src/render/const_.rs
@@ -15,7 +15,7 @@ pub(crate) fn render_const<'a>(
     ctx: RenderContext<'a>,
     const_: hir::Const,
 ) -> Option<CompletionItem> {
-    ConstRender::new(ctx, const_).render()
+    ConstRender::new(ctx, const_)?.render()
 }
 
 #[derive(Debug)]
@@ -26,9 +26,9 @@ struct ConstRender<'a> {
 }
 
 impl<'a> ConstRender<'a> {
-    fn new(ctx: RenderContext<'a>, const_: hir::Const) -> ConstRender<'a> {
-        let ast_node = const_.source(ctx.db()).value;
-        ConstRender { ctx, const_, ast_node }
+    fn new(ctx: RenderContext<'a>, const_: hir::Const) -> Option<ConstRender<'a>> {
+        let ast_node = const_.source(ctx.db())?.value;
+        Some(ConstRender { ctx, const_, ast_node })
     }
 
     fn render(self) -> Option<CompletionItem> {
diff --git a/crates/completion/src/render/function.rs b/crates/completion/src/render/function.rs
index 316e05b52..081be14f4 100644
--- a/crates/completion/src/render/function.rs
+++ b/crates/completion/src/render/function.rs
@@ -14,9 +14,9 @@ pub(crate) fn render_fn<'a>(
     import_to_add: Option<ImportEdit>,
     local_name: Option<String>,
     fn_: hir::Function,
-) -> CompletionItem {
+) -> Option<CompletionItem> {
     let _p = profile::span("render_fn");
-    FunctionRender::new(ctx, local_name, fn_).render(import_to_add)
+    Some(FunctionRender::new(ctx, local_name, fn_)?.render(import_to_add))
 }
 
 #[derive(Debug)]
@@ -32,11 +32,11 @@ impl<'a> FunctionRender<'a> {
         ctx: RenderContext<'a>,
         local_name: Option<String>,
         fn_: hir::Function,
-    ) -> FunctionRender<'a> {
+    ) -> Option<FunctionRender<'a>> {
         let name = local_name.unwrap_or_else(|| fn_.name(ctx.db()).to_string());
-        let ast_node = fn_.source(ctx.db()).value;
+        let ast_node = fn_.source(ctx.db())?.value;
 
-        FunctionRender { ctx, name, func: fn_, ast_node }
+        Some(FunctionRender { ctx, name, func: fn_, ast_node })
     }
 
     fn render(self, import_to_add: Option<ImportEdit>) -> CompletionItem {
diff --git a/crates/completion/src/render/macro_.rs b/crates/completion/src/render/macro_.rs
index dac79592f..6f4f9945c 100644
--- a/crates/completion/src/render/macro_.rs
+++ b/crates/completion/src/render/macro_.rs
@@ -39,20 +39,13 @@ impl<'a> MacroRender<'a> {
     }
 
     fn render(&self, import_to_add: Option<ImportEdit>) -> Option<CompletionItem> {
-        // FIXME: Currently proc-macro do not have ast-node,
-        // such that it does not have source
-        // more discussion: https://github.com/rust-analyzer/rust-analyzer/issues/6913
-        if self.macro_.is_proc_macro() {
-            return None;
-        }
-
         let mut builder =
             CompletionItem::new(CompletionKind::Reference, self.ctx.source_range(), &self.label())
                 .kind(CompletionItemKind::Macro)
                 .set_documentation(self.docs.clone())
                 .set_deprecated(self.ctx.is_deprecated(self.macro_))
                 .add_import(import_to_add)
-                .detail(self.detail());
+                .set_detail(self.detail());
 
         let needs_bang = self.needs_bang();
         builder = match self.ctx.snippet_cap() {
@@ -95,9 +88,9 @@ impl<'a> MacroRender<'a> {
         format!("{}!", self.name)
     }
 
-    fn detail(&self) -> String {
-        let ast_node = self.macro_.source(self.ctx.db()).value;
-        macro_label(&ast_node)
+    fn detail(&self) -> Option<String> {
+        let ast_node = self.macro_.source(self.ctx.db())?.value;
+        Some(macro_label(&ast_node))
     }
 }
 
diff --git a/crates/completion/src/render/type_alias.rs b/crates/completion/src/render/type_alias.rs
index 9605c7fa9..69b445b9c 100644
--- a/crates/completion/src/render/type_alias.rs
+++ b/crates/completion/src/render/type_alias.rs
@@ -15,7 +15,7 @@ pub(crate) fn render_type_alias<'a>(
     ctx: RenderContext<'a>,
     type_alias: hir::TypeAlias,
 ) -> Option<CompletionItem> {
-    TypeAliasRender::new(ctx, type_alias).render()
+    TypeAliasRender::new(ctx, type_alias)?.render()
 }
 
 #[derive(Debug)]
@@ -26,9 +26,9 @@ struct TypeAliasRender<'a> {
 }
 
 impl<'a> TypeAliasRender<'a> {
-    fn new(ctx: RenderContext<'a>, type_alias: hir::TypeAlias) -> TypeAliasRender<'a> {
-        let ast_node = type_alias.source(ctx.db()).value;
-        TypeAliasRender { ctx, type_alias, ast_node }
+    fn new(ctx: RenderContext<'a>, type_alias: hir::TypeAlias) -> Option<TypeAliasRender<'a>> {
+        let ast_node = type_alias.source(ctx.db())?.value;
+        Some(TypeAliasRender { ctx, type_alias, ast_node })
     }
 
     fn render(self) -> Option<CompletionItem> {
diff --git a/crates/hir/src/attrs.rs b/crates/hir/src/attrs.rs
index d32ce37ed..99fb65bac 100644
--- a/crates/hir/src/attrs.rs
+++ b/crates/hir/src/attrs.rs
@@ -3,15 +3,15 @@ use hir_def::{
     attr::{Attrs, Documentation},
     path::ModPath,
     resolver::HasResolver,
-    AttrDefId, ModuleDefId,
+    AttrDefId, GenericParamId, ModuleDefId,
 };
 use hir_expand::hygiene::Hygiene;
 use hir_ty::db::HirDatabase;
 use syntax::ast;
 
 use crate::{
-    Adt, Const, Enum, Field, Function, MacroDef, Module, ModuleDef, Static, Struct, Trait,
-    TypeAlias, Union, Variant,
+    Adt, Const, ConstParam, Enum, Field, Function, GenericParam, LifetimeParam, MacroDef, Module,
+    ModuleDef, Static, Struct, Trait, TypeAlias, TypeParam, Union, Variant,
 };
 
 pub trait HasAttrs {
@@ -62,25 +62,27 @@ impl_has_attrs![
     (Function, FunctionId),
     (Adt, AdtId),
     (Module, ModuleId),
+    (GenericParam, GenericParamId),
 ];
 
-macro_rules! impl_has_attrs_adt {
-    ($($adt:ident),*) => {$(
-        impl HasAttrs for $adt {
+macro_rules! impl_has_attrs_enum {
+    ($($variant:ident),* for $enum:ident) => {$(
+        impl HasAttrs for $variant {
             fn attrs(self, db: &dyn HirDatabase) -> Attrs {
-                Adt::$adt(self).attrs(db)
+                $enum::$variant(self).attrs(db)
             }
             fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
-                Adt::$adt(self).docs(db)
+                $enum::$variant(self).docs(db)
             }
             fn resolve_doc_path(self, db: &dyn HirDatabase, link: &str, ns: Option<Namespace>) -> Option<ModuleDef> {
-                Adt::$adt(self).resolve_doc_path(db, link, ns)
+                $enum::$variant(self).resolve_doc_path(db, link, ns)
             }
         }
     )*};
 }
 
-impl_has_attrs_adt![Struct, Union, Enum];
+impl_has_attrs_enum![Struct, Union, Enum for Adt];
+impl_has_attrs_enum![TypeParam, ConstParam, LifetimeParam for GenericParam];
 
 fn resolve_doc_path(
     db: &dyn HirDatabase,
@@ -99,6 +101,12 @@ fn resolve_doc_path(
         AttrDefId::TraitId(it) => it.resolver(db.upcast()),
         AttrDefId::TypeAliasId(it) => it.resolver(db.upcast()),
         AttrDefId::ImplId(it) => it.resolver(db.upcast()),
+        AttrDefId::GenericParamId(it) => match it {
+            GenericParamId::TypeParamId(it) => it.parent,
+            GenericParamId::LifetimeParamId(it) => it.parent,
+            GenericParamId::ConstParamId(it) => it.parent,
+        }
+        .resolver(db.upcast()),
         AttrDefId::MacroDefId(_) => return None,
     };
     let path = ast::Path::parse(link).ok()?;
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index b7ded3478..62eccf475 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -18,10 +18,10 @@ use hir_def::{
     resolver::{HasResolver, Resolver},
     src::HasSource as _,
     type_ref::{Mutability, TypeRef},
-    AdtId, AssocContainerId, AssocItemId, AssocItemLoc, AttrDefId, ConstId, DefWithBodyId, EnumId,
-    FunctionId, GenericDefId, HasModule, ImplId, LifetimeParamId, LocalEnumVariantId, LocalFieldId,
-    LocalModuleId, Lookup, ModuleId, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
-    UnionId,
+    AdtId, AssocContainerId, AssocItemId, AssocItemLoc, AttrDefId, ConstId, ConstParamId,
+    DefWithBodyId, EnumId, FunctionId, GenericDefId, HasModule, ImplId, LifetimeParamId,
+    LocalEnumVariantId, LocalFieldId, LocalModuleId, Lookup, ModuleId, StaticId, StructId, TraitId,
+    TypeAliasId, TypeParamId, UnionId,
 };
 use hir_def::{find_path::PrefixKind, item_scope::ItemInNs, visibility::Visibility};
 use hir_expand::{
@@ -39,7 +39,7 @@ use hir_ty::{
     TyDefId, TyKind, TypeCtor,
 };
 use rustc_hash::FxHashSet;
-use stdx::impl_from;
+use stdx::{format_to, impl_from};
 use syntax::{
     ast::{self, AttrsOwner, NameOwner},
     AstNode, SmolStr,
@@ -797,6 +797,19 @@ impl Function {
     pub fn has_body(self, db: &dyn HirDatabase) -> bool {
         db.function_data(self.id).has_body
     }
+
+    /// A textual representation of the HIR of this function for debugging purposes.
+    pub fn debug_hir(self, db: &dyn HirDatabase) -> String {
+        let body = db.body(self.id.into());
+
+        let mut result = String::new();
+        format_to!(result, "HIR expressions in the body of `{}`:\n", self.name(db));
+        for (id, expr) in body.exprs.iter() {
+            format_to!(result, "{:?}: {:?}\n", id, expr);
+        }
+
+        result
+    }
 }
 
 // Note: logically, this belongs to `hir_ty`, but we are not using it there yet.
@@ -983,13 +996,7 @@ impl MacroDef {
 
     /// XXX: this parses the file
     pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
-        // FIXME: Currently proc-macro do not have ast-node,
-        // such that it does not have source
-        // more discussion: https://github.com/rust-analyzer/rust-analyzer/issues/6913
-        if self.is_proc_macro() {
-            return None;
-        }
-        self.source(db).value.name().map(|it| it.as_name())
+        self.source(db)?.value.name().map(|it| it.as_name())
     }
 
     /// Indicate it is a proc-macro
@@ -1125,7 +1132,12 @@ impl GenericDef {
                 id: LifetimeParamId { parent: self.into(), local_id },
             })
             .map(GenericParam::LifetimeParam);
-        ty_params.chain(lt_params).collect()
+        let const_params = generics
+            .consts
+            .iter()
+            .map(|(local_id, _)| ConstParam { id: ConstParamId { parent: self.into(), local_id } })
+            .map(GenericParam::ConstParam);
+        ty_params.chain(lt_params).chain(const_params).collect()
     }
 
     pub fn type_params(self, db: &dyn HirDatabase) -> Vec<TypeParam> {
@@ -1237,8 +1249,9 @@ impl Label {
 pub enum GenericParam {
     TypeParam(TypeParam),
     LifetimeParam(LifetimeParam),
+    ConstParam(ConstParam),
 }
-impl_from!(TypeParam, LifetimeParam for GenericParam);
+impl_from!(TypeParam, LifetimeParam, ConstParam for GenericParam);
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct TypeParam {
@@ -1300,6 +1313,26 @@ impl LifetimeParam {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct ConstParam {
+    pub(crate) id: ConstParamId,
+}
+
+impl ConstParam {
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        let params = db.generic_params(self.id.parent);
+        params.consts[self.id.local_id].name.clone()
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.parent.module(db.upcast()).into()
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> GenericDef {
+        self.id.parent.into()
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Impl {
     pub(crate) id: ImplId,
@@ -1352,7 +1385,7 @@ impl Impl {
     }
 
     pub fn is_builtin_derive(self, db: &dyn HirDatabase) -> Option<InFile<ast::Attr>> {
-        let src = self.source(db);
+        let src = self.source(db)?;
         let item = src.file_id.is_builtin_derive(db.upcast())?;
         let hygenic = hir_expand::hygiene::Hygiene::new(db.upcast(), item.file_id);
 
diff --git a/crates/hir/src/from_id.rs b/crates/hir/src/from_id.rs
index a0792b9a6..3e47a5e9d 100644
--- a/crates/hir/src/from_id.rs
+++ b/crates/hir/src/from_id.rs
@@ -6,13 +6,13 @@
 use hir_def::{
     expr::{LabelId, PatId},
     item_scope::ItemInNs,
-    AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, GenericDefId, ModuleDefId,
-    VariantId,
+    AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, GenericDefId, GenericParamId,
+    ModuleDefId, VariantId,
 };
 
 use crate::{
-    Adt, AssocItem, DefWithBody, Field, GenericDef, Label, Local, MacroDef, ModuleDef, Variant,
-    VariantDef,
+    code_model::GenericParam, Adt, AssocItem, DefWithBody, Field, GenericDef, Label, Local,
+    MacroDef, ModuleDef, Variant, VariantDef,
 };
 
 macro_rules! from_id {
@@ -44,6 +44,7 @@ from_id![
     (hir_def::ImplId, crate::Impl),
     (hir_def::TypeParamId, crate::TypeParam),
     (hir_def::LifetimeParamId, crate::LifetimeParam),
+    (hir_def::ConstParamId, crate::ConstParam),
     (hir_expand::MacroDefId, crate::MacroDef)
 ];
 
@@ -67,6 +68,26 @@ impl From<Adt> for AdtId {
     }
 }
 
+impl From<GenericParamId> for GenericParam {
+    fn from(id: GenericParamId) -> Self {
+        match id {
+            GenericParamId::TypeParamId(it) => GenericParam::TypeParam(it.into()),
+            GenericParamId::LifetimeParamId(it) => GenericParam::LifetimeParam(it.into()),
+            GenericParamId::ConstParamId(it) => GenericParam::ConstParam(it.into()),
+        }
+    }
+}
+
+impl From<GenericParam> for GenericParamId {
+    fn from(id: GenericParam) -> Self {
+        match id {
+            GenericParam::TypeParam(it) => GenericParamId::TypeParamId(it.id),
+            GenericParam::LifetimeParam(it) => GenericParamId::LifetimeParamId(it.id),
+            GenericParam::ConstParam(it) => GenericParamId::ConstParamId(it.id),
+        }
+    }
+}
+
 impl From<EnumVariantId> for Variant {
     fn from(id: EnumVariantId) -> Self {
         Variant { parent: id.parent.into(), id: id.local_id }
diff --git a/crates/hir/src/has_source.rs b/crates/hir/src/has_source.rs
index 0dc07c33e..7c57d8378 100644
--- a/crates/hir/src/has_source.rs
+++ b/crates/hir/src/has_source.rs
@@ -10,13 +10,13 @@ use hir_expand::InFile;
 use syntax::ast;
 
 use crate::{
-    db::HirDatabase, Const, Enum, Field, FieldSource, Function, Impl, LifetimeParam, MacroDef,
-    Module, Static, Struct, Trait, TypeAlias, TypeParam, Union, Variant,
+    db::HirDatabase, Const, ConstParam, Enum, Field, FieldSource, Function, Impl, LifetimeParam,
+    MacroDef, Module, Static, Struct, Trait, TypeAlias, TypeParam, Union, Variant,
 };
 
 pub trait HasSource {
     type Ast;
-    fn source(self, db: &dyn HirDatabase) -> InFile<Self::Ast>;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>>;
 }
 
 /// NB: Module is !HasSource, because it has two source nodes at the same time:
@@ -46,97 +46,104 @@ impl Module {
 
 impl HasSource for Field {
     type Ast = FieldSource;
-    fn source(self, db: &dyn HirDatabase) -> InFile<FieldSource> {
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
         let var = VariantId::from(self.parent);
         let src = var.child_source(db.upcast());
-        src.map(|it| match it[self.id].clone() {
+        let field_source = src.map(|it| match it[self.id].clone() {
             Either::Left(it) => FieldSource::Pos(it),
             Either::Right(it) => FieldSource::Named(it),
-        })
+        });
+        Some(field_source)
     }
 }
 impl HasSource for Struct {
     type Ast = ast::Struct;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Struct> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for Union {
     type Ast = ast::Union;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Union> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for Enum {
     type Ast = ast::Enum;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Enum> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for Variant {
     type Ast = ast::Variant;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Variant> {
-        self.parent.id.child_source(db.upcast()).map(|map| map[self.id].clone())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<ast::Variant>> {
+        Some(self.parent.id.child_source(db.upcast()).map(|map| map[self.id].clone()))
     }
 }
 impl HasSource for Function {
     type Ast = ast::Fn;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Fn> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for Const {
     type Ast = ast::Const;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Const> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for Static {
     type Ast = ast::Static;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Static> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for Trait {
     type Ast = ast::Trait;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Trait> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for TypeAlias {
     type Ast = ast::TypeAlias;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::TypeAlias> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 impl HasSource for MacroDef {
     type Ast = ast::Macro;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Macro> {
-        InFile {
-            file_id: self.id.ast_id.expect("MacroDef without ast_id").file_id,
-            value: self.id.ast_id.expect("MacroDef without ast_id").to_node(db.upcast()),
-        }
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        let ast_id = self.id.ast_id?;
+        Some(InFile { file_id: ast_id.file_id, value: ast_id.to_node(db.upcast()) })
     }
 }
 impl HasSource for Impl {
     type Ast = ast::Impl;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::Impl> {
-        self.id.lookup(db.upcast()).source(db.upcast())
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
     }
 }
 
 impl HasSource for TypeParam {
     type Ast = Either<ast::Trait, ast::TypeParam>;
-    fn source(self, db: &dyn HirDatabase) -> InFile<Self::Ast> {
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
         let child_source = self.id.parent.child_source(db.upcast());
-        child_source.map(|it| it[self.id.local_id].clone())
+        Some(child_source.map(|it| it[self.id.local_id].clone()))
     }
 }
 
 impl HasSource for LifetimeParam {
     type Ast = ast::LifetimeParam;
-    fn source(self, db: &dyn HirDatabase) -> InFile<Self::Ast> {
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        let child_source = self.id.parent.child_source(db.upcast());
+        Some(child_source.map(|it| it[self.id.local_id].clone()))
+    }
+}
+
+impl HasSource for ConstParam {
+    type Ast = ast::ConstParam;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
         let child_source = self.id.parent.child_source(db.upcast());
-        child_source.map(|it| it[self.id.local_id].clone())
+        Some(child_source.map(|it| it[self.id.local_id].clone()))
     }
 }
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 7ac9fd507..769945c47 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -34,9 +34,10 @@ pub use crate::{
     attrs::{HasAttrs, Namespace},
     code_model::{
         Access, Adt, AsAssocItem, AssocItem, AssocItemContainer, Callable, CallableKind, Const,
-        Crate, CrateDependency, DefWithBody, Enum, Field, FieldSource, Function, GenericDef,
-        HasVisibility, Impl, Label, LifetimeParam, Local, MacroDef, Module, ModuleDef, ScopeDef,
-        Static, Struct, Trait, Type, TypeAlias, TypeParam, Union, Variant, VariantDef,
+        ConstParam, Crate, CrateDependency, DefWithBody, Enum, Field, FieldSource, Function,
+        GenericDef, GenericParam, HasVisibility, Impl, Label, LifetimeParam, Local, MacroDef,
+        Module, ModuleDef, ScopeDef, Static, Struct, Trait, Type, TypeAlias, TypeParam, Union,
+        Variant, VariantDef,
     },
     has_source::HasSource,
     semantics::{PathResolution, Semantics, SemanticsScope},
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index 67cd16e31..cd689c869 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -25,9 +25,9 @@ use crate::{
     diagnostics::Diagnostic,
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
-    AssocItem, Callable, Crate, Field, Function, HirFileId, Impl, InFile, Label, LifetimeParam,
-    Local, MacroDef, Module, ModuleDef, Name, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam,
-    VariantDef,
+    AssocItem, Callable, ConstParam, Crate, Field, Function, HirFileId, Impl, InFile, Label,
+    LifetimeParam, Local, MacroDef, Module, ModuleDef, Name, Path, ScopeDef, Trait, Type,
+    TypeAlias, TypeParam, VariantDef,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -38,6 +38,7 @@ pub enum PathResolution {
     Local(Local),
     /// A generic parameter
     TypeParam(TypeParam),
+    ConstParam(ConstParam),
     SelfType(Impl),
     Macro(MacroDef),
     AssocItem(AssocItem),
@@ -59,7 +60,9 @@ impl PathResolution {
             PathResolution::Def(ModuleDef::TypeAlias(alias)) => {
                 Some(TypeNs::TypeAliasId((*alias).into()))
             }
-            PathResolution::Local(_) | PathResolution::Macro(_) => None,
+            PathResolution::Local(_) | PathResolution::Macro(_) | PathResolution::ConstParam(_) => {
+                None
+            }
             PathResolution::TypeParam(param) => Some(TypeNs::GenericParam((*param).into())),
             PathResolution::SelfType(impl_def) => Some(TypeNs::SelfType((*impl_def).into())),
             PathResolution::AssocItem(AssocItem::Const(_))
@@ -744,6 +747,7 @@ to_def_impls![
     (crate::Variant, ast::Variant, enum_variant_to_def),
     (crate::TypeParam, ast::TypeParam, type_param_to_def),
     (crate::LifetimeParam, ast::LifetimeParam, lifetime_param_to_def),
+    (crate::ConstParam, ast::ConstParam, const_param_to_def),
     (crate::MacroDef, ast::MacroRules, macro_rules_to_def),
     (crate::Local, ast::IdentPat, bind_pat_to_def),
     (crate::Label, ast::Label, label_to_def),
diff --git a/crates/hir/src/semantics/source_to_def.rs b/crates/hir/src/semantics/source_to_def.rs
index 424e6e8a9..4b9ebff72 100644
--- a/crates/hir/src/semantics/source_to_def.rs
+++ b/crates/hir/src/semantics/source_to_def.rs
@@ -6,9 +6,9 @@ use hir_def::{
     dyn_map::DynMap,
     expr::{LabelId, PatId},
     keys::{self, Key},
-    ConstId, DefWithBodyId, EnumId, EnumVariantId, FieldId, FunctionId, GenericDefId, ImplId,
-    LifetimeParamId, ModuleId, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
-    VariantId,
+    ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId, FieldId, FunctionId, GenericDefId,
+    ImplId, LifetimeParamId, ModuleId, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
+    UnionId, VariantId,
 };
 use hir_expand::{name::AsName, AstId, MacroDefKind};
 use rustc_hash::FxHashMap;
@@ -157,6 +157,18 @@ impl SourceToDefCtx<'_, '_> {
         dyn_map[keys::LIFETIME_PARAM].get(&src).copied()
     }
 
+    pub(super) fn const_param_to_def(
+        &mut self,
+        src: InFile<ast::ConstParam>,
+    ) -> Option<ConstParamId> {
+        let container: ChildContainer =
+            self.find_generic_param_container(src.as_ref().map(|it| it.syntax()))?.into();
+        let db = self.db;
+        let dyn_map =
+            &*self.cache.entry(container).or_insert_with(|| container.child_by_source(db));
+        dyn_map[keys::CONST_PARAM].get(&src).copied()
+    }
+
     // FIXME: use DynMap as well?
     pub(super) fn macro_rules_to_def(
         &mut self,
diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs
index bddc49c05..30a8e513d 100644
--- a/crates/hir/src/source_analyzer.rs
+++ b/crates/hir/src/source_analyzer.rs
@@ -479,6 +479,7 @@ pub(crate) fn resolve_hir_path(
                 ValueNs::StructId(it) => PathResolution::Def(Struct::from(it).into()),
                 ValueNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
                 ValueNs::ImplSelf(impl_id) => PathResolution::SelfType(impl_id.into()),
+                ValueNs::GenericParam(it) => PathResolution::ConstParam(it.into()),
             };
             Some(res)
         });
diff --git a/crates/hir_def/Cargo.toml b/crates/hir_def/Cargo.toml
index e8b581e2f..7ef966cd2 100644
--- a/crates/hir_def/Cargo.toml
+++ b/crates/hir_def/Cargo.toml
@@ -33,4 +33,4 @@ cfg = { path = "../cfg", version = "0.0.0" }
 tt = { path = "../tt", version = "0.0.0" }
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 042e119b1..6b79e7bad 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -21,7 +21,7 @@ use crate::{
     nameres::ModuleSource,
     path::{ModPath, PathKind},
     src::HasChildSource,
-    AdtId, AttrDefId, Lookup,
+    AdtId, AttrDefId, GenericParamId, Lookup,
 };
 
 /// Holds documentation
@@ -235,6 +235,25 @@ impl Attrs {
             AttrDefId::StaticId(it) => attrs_from_item_tree(it.lookup(db).id, db),
             AttrDefId::FunctionId(it) => attrs_from_item_tree(it.lookup(db).id, db),
             AttrDefId::TypeAliasId(it) => attrs_from_item_tree(it.lookup(db).id, db),
+            AttrDefId::GenericParamId(it) => match it {
+                GenericParamId::TypeParamId(it) => {
+                    let src = it.parent.child_source(db);
+                    RawAttrs::from_attrs_owner(
+                        db,
+                        src.with_value(
+                            src.value[it.local_id].as_ref().either(|it| it as _, |it| it as _),
+                        ),
+                    )
+                }
+                GenericParamId::LifetimeParamId(it) => {
+                    let src = it.parent.child_source(db);
+                    RawAttrs::from_attrs_owner(db, src.with_value(&src.value[it.local_id]))
+                }
+                GenericParamId::ConstParamId(it) => {
+                    let src = it.parent.child_source(db);
+                    RawAttrs::from_attrs_owner(db, src.with_value(&src.value[it.local_id]))
+                }
+            },
         };
 
         raw_attrs.filter(db, def.krate(db))
@@ -260,14 +279,13 @@ impl Attrs {
     }
 
     pub fn docs(&self) -> Option<Documentation> {
-        let docs = self
-            .by_key("doc")
-            .attrs()
-            .flat_map(|attr| match attr.input.as_ref()? {
-                AttrInput::Literal(s) => Some(s),
-                AttrInput::TokenTree(_) => None,
-            })
-            .intersperse(&SmolStr::new_inline("\n"))
+        let docs = self.by_key("doc").attrs().flat_map(|attr| match attr.input.as_ref()? {
+            AttrInput::Literal(s) => Some(s),
+            AttrInput::TokenTree(_) => None,
+        });
+        // FIXME: Replace `Itertools::intersperse` with `Iterator::intersperse[_with]` until the
+        // libstd api gets stabilized (https://github.com/rust-lang/rust/issues/79524).
+        let docs = Itertools::intersperse(docs, &SmolStr::new_inline("\n"))
             .map(|it| it.as_str())
             .collect::<String>();
         if docs.is_empty() {
diff --git a/crates/hir_def/src/generics.rs b/crates/hir_def/src/generics.rs
index bb8fca009..9b5b886c2 100644
--- a/crates/hir_def/src/generics.rs
+++ b/crates/hir_def/src/generics.rs
@@ -21,11 +21,11 @@ use crate::{
     keys,
     src::{HasChildSource, HasSource},
     type_ref::{LifetimeRef, TypeBound, TypeRef},
-    AdtId, GenericDefId, LifetimeParamId, LocalLifetimeParamId, LocalTypeParamId, Lookup,
-    TypeParamId,
+    AdtId, ConstParamId, GenericDefId, LifetimeParamId, LocalConstParamId, LocalLifetimeParamId,
+    LocalTypeParamId, Lookup, TypeParamId,
 };
 
-/// Data about a generic parameter (to a function, struct, impl, ...).
+/// Data about a generic type parameter (to a function, struct, impl, ...).
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct TypeParamData {
     pub name: Option<Name>,
@@ -33,12 +33,19 @@ pub struct TypeParamData {
     pub provenance: TypeParamProvenance,
 }
 
-/// Data about a generic parameter (to a function, struct, impl, ...).
+/// Data about a generic lifetime parameter (to a function, struct, impl, ...).
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct LifetimeParamData {
     pub name: Name,
 }
 
+/// Data about a generic const parameter (to a function, struct, impl, ...).
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct ConstParamData {
+    pub name: Name,
+    pub ty: TypeRef,
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum TypeParamProvenance {
     TypeParamList,
@@ -51,6 +58,7 @@ pub enum TypeParamProvenance {
 pub struct GenericParams {
     pub types: Arena<TypeParamData>,
     pub lifetimes: Arena<LifetimeParamData>,
+    pub consts: Arena<ConstParamData>,
     pub where_predicates: Vec<WherePredicate>,
 }
 
@@ -76,6 +84,7 @@ pub enum WherePredicateTypeTarget {
 pub(crate) struct SourceMap {
     pub(crate) type_params: ArenaMap<LocalTypeParamId, Either<ast::Trait, ast::TypeParam>>,
     lifetime_params: ArenaMap<LocalLifetimeParamId, ast::LifetimeParam>,
+    const_params: ArenaMap<LocalConstParamId, ast::ConstParam>,
 }
 
 impl GenericParams {
@@ -268,6 +277,13 @@ impl GenericParams {
             let lifetime_ref = LifetimeRef::new_name(name);
             self.fill_bounds(&lower_ctx, &lifetime_param, Either::Right(lifetime_ref));
         }
+        for const_param in params.const_params() {
+            let name = const_param.name().map_or_else(Name::missing, |it| it.as_name());
+            let ty = const_param.ty().map_or(TypeRef::Error, |it| TypeRef::from_ast(lower_ctx, it));
+            let param = ConstParamData { name, ty };
+            let param_id = self.consts.alloc(param);
+            sm.const_params.insert(param_id, const_param.clone());
+        }
     }
 
     fn fill_where_predicates(&mut self, lower_ctx: &LowerCtx, where_clause: ast::WhereClause) {
@@ -353,12 +369,16 @@ impl GenericParams {
         });
     }
 
-    pub fn find_by_name(&self, name: &Name) -> Option<LocalTypeParamId> {
+    pub fn find_type_by_name(&self, name: &Name) -> Option<LocalTypeParamId> {
         self.types
             .iter()
             .find_map(|(id, p)| if p.name.as_ref() == Some(name) { Some(id) } else { None })
     }
 
+    pub fn find_const_by_name(&self, name: &Name) -> Option<LocalConstParamId> {
+        self.consts.iter().find_map(|(id, p)| if p.name == *name { Some(id) } else { None })
+    }
+
     pub fn find_trait_self_param(&self) -> Option<LocalTypeParamId> {
         self.types.iter().find_map(|(id, p)| {
             if p.provenance == TypeParamProvenance::TraitSelf {
@@ -390,6 +410,16 @@ impl HasChildSource<LocalLifetimeParamId> for GenericDefId {
     }
 }
 
+impl HasChildSource<LocalConstParamId> for GenericDefId {
+    type Value = ast::ConstParam;
+    fn child_source(
+        &self,
+        db: &dyn DefDatabase,
+    ) -> InFile<ArenaMap<LocalConstParamId, Self::Value>> {
+        GenericParams::new(db, *self).1.map(|source_maps| source_maps.const_params)
+    }
+}
+
 impl ChildBySource for GenericDefId {
     fn child_by_source(&self, db: &dyn DefDatabase) -> DynMap {
         let mut res = DynMap::default();
@@ -406,6 +436,10 @@ impl ChildBySource for GenericDefId {
             let id = LifetimeParamId { parent: *self, local_id };
             res[keys::LIFETIME_PARAM].insert(sm.with_value(src.clone()), id);
         }
+        for (local_id, src) in sm.value.const_params.iter() {
+            let id = ConstParamId { parent: *self, local_id };
+            res[keys::CONST_PARAM].insert(sm.with_value(src.clone()), id);
+        }
         res
     }
 }
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index 100dbf5d6..b6f510731 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -260,6 +260,7 @@ impl GenericParamsStorage {
     fn alloc(&mut self, params: GenericParams) -> GenericParamsId {
         if params.types.is_empty()
             && params.lifetimes.is_empty()
+            && params.consts.is_empty()
             && params.where_predicates.is_empty()
         {
             return GenericParamsId::EMPTY;
@@ -269,8 +270,12 @@ impl GenericParamsStorage {
     }
 }
 
-static EMPTY_GENERICS: GenericParams =
-    GenericParams { types: Arena::new(), lifetimes: Arena::new(), where_predicates: Vec::new() };
+static EMPTY_GENERICS: GenericParams = GenericParams {
+    types: Arena::new(),
+    lifetimes: Arena::new(),
+    consts: Arena::new(),
+    where_predicates: Vec::new(),
+};
 
 #[derive(Default, Debug, Eq, PartialEq)]
 struct ItemTreeData {
diff --git a/crates/hir_def/src/keys.rs b/crates/hir_def/src/keys.rs
index 9c585de2c..89b3ed868 100644
--- a/crates/hir_def/src/keys.rs
+++ b/crates/hir_def/src/keys.rs
@@ -8,8 +8,8 @@ use syntax::{ast, AstNode, AstPtr};
 
 use crate::{
     dyn_map::{DynMap, Policy},
-    ConstId, EnumId, EnumVariantId, FieldId, FunctionId, ImplId, LifetimeParamId, StaticId,
-    StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
+    ConstId, ConstParamId, EnumId, EnumVariantId, FieldId, FunctionId, ImplId, LifetimeParamId,
+    StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
 };
 
 pub type Key<K, V> = crate::dyn_map::Key<InFile<K>, V, AstPtrPolicy<K, V>>;
@@ -29,6 +29,7 @@ pub const TUPLE_FIELD: Key<ast::TupleField, FieldId> = Key::new();
 pub const RECORD_FIELD: Key<ast::RecordField, FieldId> = Key::new();
 pub const TYPE_PARAM: Key<ast::TypeParam, TypeParamId> = Key::new();
 pub const LIFETIME_PARAM: Key<ast::LifetimeParam, LifetimeParamId> = Key::new();
+pub const CONST_PARAM: Key<ast::ConstParam, ConstParamId> = Key::new();
 
 pub const MACRO: Key<ast::MacroCall, MacroDefId> = Key::new();
 
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index ba09a9126..211cb2faf 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -232,6 +232,13 @@ pub struct LifetimeParamId {
 pub type LocalLifetimeParamId = Idx<generics::LifetimeParamData>;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ConstParamId {
+    pub parent: GenericDefId,
+    pub local_id: LocalConstParamId,
+}
+pub type LocalConstParamId = Idx<generics::ConstParamData>;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum ContainerId {
     ModuleId(ModuleId),
     DefWithBodyId(DefWithBodyId),
@@ -254,6 +261,15 @@ pub enum AdtId {
 }
 impl_from!(StructId, UnionId, EnumId for AdtId);
 
+/// A generic param
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum GenericParamId {
+    TypeParamId(TypeParamId),
+    LifetimeParamId(LifetimeParamId),
+    ConstParamId(ConstParamId),
+}
+impl_from!(TypeParamId, LifetimeParamId, ConstParamId for GenericParamId);
+
 /// The defs which can be visible in the module.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum ModuleDefId {
@@ -350,6 +366,7 @@ pub enum AttrDefId {
     TypeAliasId(TypeAliasId),
     MacroDefId(MacroDefId),
     ImplId(ImplId),
+    GenericParamId(GenericParamId),
 }
 
 impl_from!(
@@ -363,7 +380,8 @@ impl_from!(
     TraitId,
     TypeAliasId,
     MacroDefId,
-    ImplId
+    ImplId,
+    GenericParamId
     for AttrDefId
 );
 
@@ -488,6 +506,15 @@ impl AttrDefId {
             AttrDefId::TraitId(it) => it.lookup(db).container.module(db).krate,
             AttrDefId::TypeAliasId(it) => it.lookup(db).module(db).krate,
             AttrDefId::ImplId(it) => it.lookup(db).container.module(db).krate,
+            AttrDefId::GenericParamId(it) => {
+                match it {
+                    GenericParamId::TypeParamId(it) => it.parent,
+                    GenericParamId::LifetimeParamId(it) => it.parent,
+                    GenericParamId::ConstParamId(it) => it.parent,
+                }
+                .module(db)
+                .krate
+            }
             // FIXME: `MacroDefId` should store the defining module, then this can implement
             // `HasModule`
             AttrDefId::MacroDefId(it) => it.krate,
diff --git a/crates/hir_def/src/resolver.rs b/crates/hir_def/src/resolver.rs
index f8cc5e075..129f1dbac 100644
--- a/crates/hir_def/src/resolver.rs
+++ b/crates/hir_def/src/resolver.rs
@@ -20,9 +20,9 @@ use crate::{
     path::{ModPath, PathKind},
     per_ns::PerNs,
     visibility::{RawVisibility, Visibility},
-    AdtId, AssocContainerId, ConstId, ContainerId, DefWithBodyId, EnumId, EnumVariantId,
-    FunctionId, GenericDefId, HasModule, ImplId, LocalModuleId, Lookup, ModuleDefId, ModuleId,
-    StaticId, StructId, TraitId, TypeAliasId, TypeParamId, VariantId,
+    AdtId, AssocContainerId, ConstId, ConstParamId, ContainerId, DefWithBodyId, EnumId,
+    EnumVariantId, FunctionId, GenericDefId, HasModule, ImplId, LocalModuleId, Lookup, ModuleDefId,
+    ModuleId, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, VariantId,
 };
 
 #[derive(Debug, Clone, Default)]
@@ -93,6 +93,7 @@ pub enum ValueNs {
     StaticId(StaticId),
     StructId(StructId),
     EnumVariantId(EnumVariantId),
+    GenericParam(ConstParamId),
 }
 
 impl Resolver {
@@ -163,7 +164,7 @@ impl Resolver {
                 }
 
                 Scope::GenericParams { params, def } => {
-                    if let Some(local_id) = params.find_by_name(first_name) {
+                    if let Some(local_id) = params.find_type_by_name(first_name) {
                         let idx = if path.segments.len() == 1 { None } else { Some(1) };
                         return Some((
                             TypeNs::GenericParam(TypeParamId { local_id, parent: *def }),
@@ -285,11 +286,17 @@ impl Resolver {
                 Scope::ExprScope(_) => continue,
 
                 Scope::GenericParams { params, def } if n_segments > 1 => {
-                    if let Some(local_id) = params.find_by_name(first_name) {
+                    if let Some(local_id) = params.find_type_by_name(first_name) {
                         let ty = TypeNs::GenericParam(TypeParamId { local_id, parent: *def });
                         return Some(ResolveValueResult::Partial(ty, 1));
                     }
                 }
+                Scope::GenericParams { params, def } if n_segments == 1 => {
+                    if let Some(local_id) = params.find_const_by_name(first_name) {
+                        let val = ValueNs::GenericParam(ConstParamId { local_id, parent: *def });
+                        return Some(ResolveValueResult::ValueNs(val));
+                    }
+                }
                 Scope::GenericParams { .. } => continue,
 
                 Scope::ImplDefScope(impl_) => {
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 06f0a3ed9..0a0d021e0 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -404,7 +404,7 @@ fn to_fragment_kind(db: &dyn AstDatabase, id: MacroCallId) -> FragmentKind {
         TRY_EXPR => FragmentKind::Expr,
         TUPLE_EXPR => FragmentKind::Expr,
         PAREN_EXPR => FragmentKind::Expr,
-
+        ARRAY_EXPR => FragmentKind::Expr,
         FOR_EXPR => FragmentKind::Expr,
         PATH_EXPR => FragmentKind::Expr,
         CLOSURE_EXPR => FragmentKind::Expr,
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index 6354b090d..ae7b51a08 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -218,6 +218,12 @@ fn eager_macro_recur(
             }
         };
 
+        // check if the whole original sytnax is replaced
+        // Note that SyntaxRewriter cannot replace the root node itself
+        if child.syntax() == &original {
+            return Ok(insert);
+        }
+
         rewriter.replace(child.syntax(), &insert);
     }
 
diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index 2dfccd191..3d1778590 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -31,7 +31,7 @@ syntax = { path = "../syntax", version = "0.0.0" }
 test_utils = { path = "../test_utils", version = "0.0.0" }
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
 tracing = "0.1"
 tracing-subscriber = { version = "0.2", default-features = false, features = ["env-filter", "registry"] }
 tracing-tree = { version = "0.1.4" }
diff --git a/crates/hir_ty/src/db.rs b/crates/hir_ty/src/db.rs
index 66bdb8e88..f3567c49e 100644
--- a/crates/hir_ty/src/db.rs
+++ b/crates/hir_ty/src/db.rs
@@ -5,8 +5,8 @@ use std::sync::Arc;
 use arena::map::ArenaMap;
 use base_db::{impl_intern_key, salsa, CrateId, Upcast};
 use hir_def::{
-    db::DefDatabase, expr::ExprId, DefWithBodyId, FunctionId, GenericDefId, ImplId, LocalFieldId,
-    TypeParamId, VariantId,
+    db::DefDatabase, expr::ExprId, ConstParamId, DefWithBodyId, FunctionId, GenericDefId, ImplId,
+    LocalFieldId, TypeParamId, VariantId,
 };
 
 use crate::{
@@ -37,6 +37,9 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[salsa::cycle(crate::lower::impl_self_ty_recover)]
     fn impl_self_ty(&self, def: ImplId) -> Binders<Ty>;
 
+    #[salsa::invoke(crate::lower::const_param_ty_query)]
+    fn const_param_ty(&self, def: ConstParamId) -> Ty;
+
     #[salsa::invoke(crate::lower::impl_trait_query)]
     fn impl_trait(&self, def: ImplId) -> Option<Binders<TraitRef>>;
 
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 849415706..b4e453411 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -156,7 +156,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         // FIXME: Due to shortcomings in the current type system implementation, only emit this
         // diagnostic if there are no type mismatches in the containing function.
         if self.infer.type_mismatches.iter().next().is_some() {
-            return Some(());
+            return None;
         }
 
         let is_method_call = matches!(expr, Expr::MethodCall { .. });
@@ -170,6 +170,14 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                 let mut args = args.clone();
                 args.insert(0, *receiver);
 
+                let receiver = &self.infer.type_of_expr[*receiver];
+                if receiver.strip_references().is_unknown() {
+                    // if the receiver is of unknown type, it's very likely we
+                    // don't know enough to correctly resolve the method call.
+                    // This is kind of a band-aid for #6975.
+                    return None;
+                }
+
                 // FIXME: note that we erase information about substs here. This
                 // is not right, but, luckily, doesn't matter as we care only
                 // about the number of params
@@ -505,6 +513,22 @@ fn f() {
     }
 
     #[test]
+    fn method_unknown_receiver() {
+        // note: this is incorrect code, so there might be errors on this in the
+        // future, but we shouldn't emit an argument count diagnostic here
+        check_diagnostics(
+            r#"
+trait Foo { fn method(&self, arg: usize) {} }
+
+fn f() {
+    let x;
+    x.method();
+}
+"#,
+        );
+    }
+
+    #[test]
     fn tuple_struct() {
         check_diagnostics(
             r#"
diff --git a/crates/hir_ty/src/infer/path.rs b/crates/hir_ty/src/infer/path.rs
index 80d7ed10e..5d541104e 100644
--- a/crates/hir_ty/src/infer/path.rs
+++ b/crates/hir_ty/src/infer/path.rs
@@ -89,6 +89,7 @@ impl<'a> InferenceContext<'a> {
                     return None;
                 }
             }
+            ValueNs::GenericParam(it) => return Some(self.db.const_param_ty(it)),
         };
 
         let ty = self.db.value_ty(typable);
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 357bd92f9..e00c7e176 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -791,6 +791,10 @@ impl Ty {
         matches!(self, Ty::Apply(ApplicationTy { ctor: TypeCtor::Never, .. }))
     }
 
+    pub fn is_unknown(&self) -> bool {
+        matches!(self, Ty::Unknown)
+    }
+
     /// If this is a `dyn Trait` type, this returns the `Trait` part.
     pub fn dyn_trait_ref(&self) -> Option<&TraitRef> {
         match self {
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 8da56cd11..222f61a11 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -16,9 +16,9 @@ use hir_def::{
     path::{GenericArg, Path, PathSegment, PathSegments},
     resolver::{HasResolver, Resolver, TypeNs},
     type_ref::{TypeBound, TypeRef},
-    AdtId, AssocContainerId, AssocItemId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId,
-    HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
-    UnionId, VariantId,
+    AdtId, AssocContainerId, AssocItemId, ConstId, ConstParamId, EnumId, EnumVariantId, FunctionId,
+    GenericDefId, HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId,
+    TypeAliasId, TypeParamId, UnionId, VariantId,
 };
 use hir_expand::name::Name;
 use smallvec::SmallVec;
@@ -1221,6 +1221,15 @@ pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binde
     Binders::new(generics.len(), Ty::from_hir(&ctx, &impl_data.target_type))
 }
 
+pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
+    let parent_data = db.generic_params(def.parent);
+    let data = &parent_data.consts[def.local_id];
+    let resolver = def.parent.resolver(db.upcast());
+    let ctx = TyLoweringContext::new(db, &resolver);
+
+    Ty::from_hir(&ctx, &data.ty)
+}
+
 pub(crate) fn impl_self_ty_recover(
     db: &dyn HirDatabase,
     _cycle: &[String],
diff --git a/crates/hir_ty/src/tests/macros.rs b/crates/hir_ty/src/tests/macros.rs
index a7656b864..1953da7be 100644
--- a/crates/hir_ty/src/tests/macros.rs
+++ b/crates/hir_ty/src/tests/macros.rs
@@ -540,6 +540,52 @@ fn bar() -> u32 {0}
 }
 
 #[test]
+fn infer_builtin_macros_include_str() {
+    check_types(
+        r#"
+//- /main.rs
+#[rustc_builtin_macro]
+macro_rules! include_str {() => {}}
+
+fn main() {
+    let a = include_str!("foo.rs");
+    a;
+} //^ &str
+
+//- /foo.rs
+hello
+"#,
+    );
+}
+
+#[test]
+fn infer_builtin_macros_include_str_with_lazy_nested() {
+    check_types(
+        r#"
+//- /main.rs
+#[rustc_builtin_macro]
+macro_rules! concat {() => {}}
+#[rustc_builtin_macro]
+macro_rules! include_str {() => {}}
+
+macro_rules! m {
+    ($x:expr) => {
+        concat!("foo", $x)
+    };
+}
+
+fn main() {
+    let a = include_str!(m!(".rs"));
+    a;
+} //^ &str
+
+//- /foo.rs
+hello
+"#,
+    );
+}
+
+#[test]
 #[ignore]
 fn include_accidentally_quadratic() {
     let file = project_dir().join("crates/syntax/test_data/accidentally_quadratic");
diff --git a/crates/hir_ty/src/tests/regression.rs b/crates/hir_ty/src/tests/regression.rs
index 307a257b1..cffe8630b 100644
--- a/crates/hir_ty/src/tests/regression.rs
+++ b/crates/hir_ty/src/tests/regression.rs
@@ -326,6 +326,24 @@ fn infer_paren_macro_call() {
 }
 
 #[test]
+fn infer_array_macro_call() {
+    check_infer(
+        r#"
+        macro_rules! bar { () => {0u32} }
+        fn test() {
+            let a = [bar!()];
+        }
+        "#,
+        expect![[r#"
+            !0..4 '0u32': u32
+            44..69 '{     ...()]; }': ()
+            54..55 'a': [u32; _]
+            58..66 '[bar!()]': [u32; _]
+        "#]],
+    );
+}
+
+#[test]
 fn bug_1030() {
     check_infer(
         r#"
diff --git a/crates/hir_ty/src/tests/simple.rs b/crates/hir_ty/src/tests/simple.rs
index a61282d5a..8d431b920 100644
--- a/crates/hir_ty/src/tests/simple.rs
+++ b/crates/hir_ty/src/tests/simple.rs
@@ -2375,3 +2375,19 @@ fn infer_operator_overload() {
         "#]],
     );
 }
+
+#[test]
+fn infer_const_params() {
+    check_infer(
+        r#"
+        fn foo<const FOO: usize>() {
+            let bar = FOO;
+        }
+        "#,
+        expect![[r#"
+            27..49 '{     ...FOO; }': ()
+            37..40 'bar': usize
+            43..46 'FOO': usize
+        "#]],
+    );
+}
diff --git a/crates/ide/Cargo.toml b/crates/ide/Cargo.toml
index f1544dbe0..bb28cca4d 100644
--- a/crates/ide/Cargo.toml
+++ b/crates/ide/Cargo.toml
@@ -36,4 +36,4 @@ completion = { path = "../completion", version = "0.0.0" }
 hir = { path = "../hir", version = "0.0.0" }
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/ide/src/call_hierarchy.rs b/crates/ide/src/call_hierarchy.rs
index 60e0cd4ad..3c2d39f5d 100644
--- a/crates/ide/src/call_hierarchy.rs
+++ b/crates/ide/src/call_hierarchy.rs
@@ -8,7 +8,7 @@ use ide_db::RootDatabase;
 use syntax::{ast, match_ast, AstNode, TextRange};
 
 use crate::{
-    display::ToNav, goto_definition, references, FilePosition, NavigationTarget, RangeInfo,
+    display::TryToNav, goto_definition, references, FilePosition, NavigationTarget, RangeInfo,
 };
 
 #[derive(Debug, Clone)]
@@ -61,7 +61,7 @@ pub(crate) fn incoming_calls(db: &RootDatabase, position: FilePosition) -> Optio
                 match node {
                     ast::Fn(it) => {
                         let def = sema.to_def(&it)?;
-                        Some(def.to_nav(sema.db))
+                        def.try_to_nav(sema.db)
                     },
                     _ => None,
                 }
@@ -99,7 +99,7 @@ pub(crate) fn outgoing_calls(db: &RootDatabase, position: FilePosition) -> Optio
                     match callable.kind() {
                         hir::CallableKind::Function(it) => {
                             let fn_def: hir::Function = it.into();
-                            let nav = fn_def.to_nav(db);
+                            let nav = fn_def.try_to_nav(db)?;
                             Some(nav)
                         }
                         _ => None,
@@ -107,7 +107,7 @@ pub(crate) fn outgoing_calls(db: &RootDatabase, position: FilePosition) -> Optio
                 }
                 FnCallNode::MethodCallExpr(expr) => {
                     let function = sema.resolve_method_call(&expr)?;
-                    Some(function.to_nav(db))
+                    function.try_to_nav(db)
                 }
             } {
                 Some((func_target, name_ref.syntax().text_range()))
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
index d79f5c170..ec0f840e9 100644
--- a/crates/ide/src/diagnostics/fixes.rs
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -156,20 +156,23 @@ fn missing_record_expr_field_fix(
     let record_fields = match VariantDef::from(def_id) {
         VariantDef::Struct(s) => {
             module = s.module(sema.db);
-            let source = s.source(sema.db);
+            #[allow(deprecated)]
+            let source = s.source(sema.db)?;
             def_file_id = source.file_id;
             let fields = source.value.field_list()?;
             record_field_list(fields)?
         }
         VariantDef::Union(u) => {
             module = u.module(sema.db);
-            let source = u.source(sema.db);
+            #[allow(deprecated)]
+            let source = u.source(sema.db)?;
             def_file_id = source.file_id;
             source.value.record_field_list()?
         }
         VariantDef::Variant(e) => {
             module = e.module(sema.db);
-            let source = e.source(sema.db);
+            #[allow(deprecated)]
+            let source = e.source(sema.db)?;
             def_file_id = source.file_id;
             let fields = source.value.field_list()?;
             record_field_list(fields)?
diff --git a/crates/ide/src/display/navigation_target.rs b/crates/ide/src/display/navigation_target.rs
index 6431e7d6d..e24c78301 100644
--- a/crates/ide/src/display/navigation_target.rs
+++ b/crates/ide/src/display/navigation_target.rs
@@ -24,6 +24,7 @@ pub enum SymbolKind {
     Impl,
     Field,
     TypeParam,
+    ConstParam,
     LifetimeParam,
     ValueParam,
     SelfParam,
@@ -209,40 +210,32 @@ impl ToNav for FileSymbol {
 impl TryToNav for Definition {
     fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
         match self {
-            Definition::Macro(it) => {
-                // FIXME: Currently proc-macro do not have ast-node,
-                // such that it does not have source
-                // more discussion: https://github.com/rust-analyzer/rust-analyzer/issues/6913
-                if it.is_proc_macro() {
-                    return None;
-                }
-                Some(it.to_nav(db))
-            }
-            Definition::Field(it) => Some(it.to_nav(db)),
+            Definition::Macro(it) => it.try_to_nav(db),
+            Definition::Field(it) => it.try_to_nav(db),
             Definition::ModuleDef(it) => it.try_to_nav(db),
-            Definition::SelfType(it) => Some(it.to_nav(db)),
+            Definition::SelfType(it) => it.try_to_nav(db),
             Definition::Local(it) => Some(it.to_nav(db)),
-            Definition::TypeParam(it) => Some(it.to_nav(db)),
-            Definition::LifetimeParam(it) => Some(it.to_nav(db)),
+            Definition::TypeParam(it) => it.try_to_nav(db),
+            Definition::LifetimeParam(it) => it.try_to_nav(db),
             Definition::Label(it) => Some(it.to_nav(db)),
+            Definition::ConstParam(it) => it.try_to_nav(db),
         }
     }
 }
 
 impl TryToNav for hir::ModuleDef {
     fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
-        let res = match self {
-            hir::ModuleDef::Module(it) => it.to_nav(db),
-            hir::ModuleDef::Function(it) => it.to_nav(db),
-            hir::ModuleDef::Adt(it) => it.to_nav(db),
-            hir::ModuleDef::Variant(it) => it.to_nav(db),
-            hir::ModuleDef::Const(it) => it.to_nav(db),
-            hir::ModuleDef::Static(it) => it.to_nav(db),
-            hir::ModuleDef::Trait(it) => it.to_nav(db),
-            hir::ModuleDef::TypeAlias(it) => it.to_nav(db),
-            hir::ModuleDef::BuiltinType(_) => return None,
-        };
-        Some(res)
+        match self {
+            hir::ModuleDef::Module(it) => Some(it.to_nav(db)),
+            hir::ModuleDef::Function(it) => it.try_to_nav(db),
+            hir::ModuleDef::Adt(it) => it.try_to_nav(db),
+            hir::ModuleDef::Variant(it) => it.try_to_nav(db),
+            hir::ModuleDef::Const(it) => it.try_to_nav(db),
+            hir::ModuleDef::Static(it) => it.try_to_nav(db),
+            hir::ModuleDef::Trait(it) => it.try_to_nav(db),
+            hir::ModuleDef::TypeAlias(it) => it.try_to_nav(db),
+            hir::ModuleDef::BuiltinType(_) => None,
+        }
     }
 }
 
@@ -277,13 +270,13 @@ impl ToNavFromAst for hir::Trait {
     const KIND: SymbolKind = SymbolKind::Trait;
 }
 
-impl<D> ToNav for D
+impl<D> TryToNav for D
 where
     D: HasSource + ToNavFromAst + Copy + HasAttrs,
     D::Ast: ast::NameOwner + ShortLabel,
 {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
-        let src = self.source(db);
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
         let mut res = NavigationTarget::from_named(
             db,
             src.as_ref().map(|it| it as &dyn ast::NameOwner),
@@ -291,7 +284,7 @@ where
         );
         res.docs = self.docs(db);
         res.description = src.value.short_label();
-        res
+        Some(res)
     }
 }
 
@@ -310,9 +303,9 @@ impl ToNav for hir::Module {
     }
 }
 
-impl ToNav for hir::Impl {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
-        let src = self.source(db);
+impl TryToNav for hir::Impl {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
         let derive_attr = self.is_builtin_derive(db);
         let frange = if let Some(item) = &derive_attr {
             item.syntax().original_file_range(db)
@@ -325,21 +318,21 @@ impl ToNav for hir::Impl {
             src.value.self_ty().map(|ty| src.with_value(ty.syntax()).original_file_range(db).range)
         };
 
-        NavigationTarget::from_syntax(
+        Some(NavigationTarget::from_syntax(
             frange.file_id,
             "impl".into(),
             focus_range,
             frange.range,
             SymbolKind::Impl,
-        )
+        ))
     }
 }
 
-impl ToNav for hir::Field {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
-        let src = self.source(db);
+impl TryToNav for hir::Field {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
 
-        match &src.value {
+        let field_source = match &src.value {
             FieldSource::Named(it) => {
                 let mut res =
                     NavigationTarget::from_named(db, src.with_value(it), SymbolKind::Field);
@@ -357,13 +350,14 @@ impl ToNav for hir::Field {
                     SymbolKind::Field,
                 )
             }
-        }
+        };
+        Some(field_source)
     }
 }
 
-impl ToNav for hir::MacroDef {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
-        let src = self.source(db);
+impl TryToNav for hir::MacroDef {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
         log::debug!("nav target {:#?}", src.value.syntax());
         let mut res = NavigationTarget::from_named(
             db,
@@ -371,26 +365,26 @@ impl ToNav for hir::MacroDef {
             SymbolKind::Macro,
         );
         res.docs = self.docs(db);
-        res
+        Some(res)
     }
 }
 
-impl ToNav for hir::Adt {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+impl TryToNav for hir::Adt {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
         match self {
-            hir::Adt::Struct(it) => it.to_nav(db),
-            hir::Adt::Union(it) => it.to_nav(db),
-            hir::Adt::Enum(it) => it.to_nav(db),
+            hir::Adt::Struct(it) => it.try_to_nav(db),
+            hir::Adt::Union(it) => it.try_to_nav(db),
+            hir::Adt::Enum(it) => it.try_to_nav(db),
         }
     }
 }
 
-impl ToNav for hir::AssocItem {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+impl TryToNav for hir::AssocItem {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
         match self {
-            AssocItem::Function(it) => it.to_nav(db),
-            AssocItem::Const(it) => it.to_nav(db),
-            AssocItem::TypeAlias(it) => it.to_nav(db),
+            AssocItem::Function(it) => it.try_to_nav(db),
+            AssocItem::Const(it) => it.try_to_nav(db),
+            AssocItem::TypeAlias(it) => it.try_to_nav(db),
         }
     }
 }
@@ -444,9 +438,9 @@ impl ToNav for hir::Label {
     }
 }
 
-impl ToNav for hir::TypeParam {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
-        let src = self.source(db);
+impl TryToNav for hir::TypeParam {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
         let full_range = match &src.value {
             Either::Left(it) => it.syntax().text_range(),
             Either::Right(it) => it.syntax().text_range(),
@@ -455,7 +449,7 @@ impl ToNav for hir::TypeParam {
             Either::Left(_) => None,
             Either::Right(it) => it.name().map(|it| it.syntax().text_range()),
         };
-        NavigationTarget {
+        Some(NavigationTarget {
             file_id: src.file_id.original_file(db),
             name: self.name(db).to_string().into(),
             kind: Some(SymbolKind::TypeParam),
@@ -464,15 +458,15 @@ impl ToNav for hir::TypeParam {
             container_name: None,
             description: None,
             docs: None,
-        }
+        })
     }
 }
 
-impl ToNav for hir::LifetimeParam {
-    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
-        let src = self.source(db);
+impl TryToNav for hir::LifetimeParam {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
         let full_range = src.value.syntax().text_range();
-        NavigationTarget {
+        Some(NavigationTarget {
             file_id: src.file_id.original_file(db),
             name: self.name(db).to_string().into(),
             kind: Some(SymbolKind::LifetimeParam),
@@ -481,7 +475,24 @@ impl ToNav for hir::LifetimeParam {
             container_name: None,
             description: None,
             docs: None,
-        }
+        })
+    }
+}
+
+impl TryToNav for hir::ConstParam {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let src = self.source(db)?;
+        let full_range = src.value.syntax().text_range();
+        Some(NavigationTarget {
+            file_id: src.file_id.original_file(db),
+            name: self.name(db).to_string().into(),
+            kind: Some(SymbolKind::ConstParam),
+            full_range,
+            focus_range: src.value.name().map(|n| n.syntax().text_range()),
+            container_name: None,
+            description: None,
+            docs: None,
+        })
     }
 }
 
diff --git a/crates/ide/src/doc_links.rs b/crates/ide/src/doc_links.rs
index e10516f43..367fac05e 100644
--- a/crates/ide/src/doc_links.rs
+++ b/crates/ide/src/doc_links.rs
@@ -193,6 +193,7 @@ fn rewrite_intra_doc_link(
         Definition::SelfType(_)
         | Definition::Local(_)
         | Definition::TypeParam(_)
+        | Definition::ConstParam(_)
         | Definition::LifetimeParam(_)
         | Definition::Label(_) => return None,
     }?;
diff --git a/crates/ide/src/goto_implementation.rs b/crates/ide/src/goto_implementation.rs
index 6eac39639..da9378a97 100644
--- a/crates/ide/src/goto_implementation.rs
+++ b/crates/ide/src/goto_implementation.rs
@@ -2,7 +2,7 @@ use hir::{Crate, Impl, Semantics};
 use ide_db::RootDatabase;
 use syntax::{algo::find_node_at_offset, ast, AstNode};
 
-use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
+use crate::{display::TryToNav, FilePosition, NavigationTarget, RangeInfo};
 
 // Feature: Go to Implementation
 //
@@ -55,7 +55,7 @@ fn impls_for_def(
         impls
             .into_iter()
             .filter(|impl_def| ty.is_equal_for_find_impls(&impl_def.target_ty(sema.db)))
-            .map(|imp| imp.to_nav(sema.db))
+            .filter_map(|imp| imp.try_to_nav(sema.db))
             .collect(),
     )
 }
@@ -69,7 +69,7 @@ fn impls_for_trait(
 
     let impls = Impl::for_trait(sema.db, krate, tr);
 
-    Some(impls.into_iter().map(|imp| imp.to_nav(sema.db)).collect())
+    Some(impls.into_iter().filter_map(|imp| imp.try_to_nav(sema.db)).collect())
 }
 
 #[cfg(test)]
diff --git a/crates/ide/src/goto_type_definition.rs b/crates/ide/src/goto_type_definition.rs
index aba6bf5dc..7e84e06be 100644
--- a/crates/ide/src/goto_type_definition.rs
+++ b/crates/ide/src/goto_type_definition.rs
@@ -1,7 +1,7 @@
 use ide_db::RootDatabase;
 use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
 
-use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
+use crate::{display::TryToNav, FilePosition, NavigationTarget, RangeInfo};
 
 // Feature: Go to Type Definition
 //
@@ -37,7 +37,7 @@ pub(crate) fn goto_type_definition(
 
     let adt_def = ty.autoderef(db).filter_map(|ty| ty.as_adt()).last()?;
 
-    let nav = adt_def.to_nav(db);
+    let nav = adt_def.try_to_nav(db)?;
     Some(RangeInfo::new(node.text_range(), vec![nav]))
 }
 
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index 73245fbe7..2737c900f 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -13,7 +13,7 @@ use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset,
 use test_utils::mark;
 
 use crate::{
-    display::{macro_label, ShortLabel, ToNav, TryToNav},
+    display::{macro_label, ShortLabel, TryToNav},
     doc_links::{remove_links, rewrite_links},
     markdown_remove::remove_markdown,
     markup::Markup,
@@ -109,6 +109,8 @@ pub(crate) fn hover(
         match node {
             ast::Name(name) => NameClass::classify(&sema, &name).and_then(|d| d.defined(sema.db)),
             ast::NameRef(name_ref) => NameRefClass::classify(&sema, &name_ref).map(|d| d.referenced(sema.db)),
+            ast::Lifetime(lifetime) => NameClass::classify_lifetime(&sema, &lifetime)
+                .map_or_else(|| NameRefClass::classify_lifetime(&sema, &lifetime).map(|d| d.referenced(sema.db)), |d| d.defined(sema.db)),
             _ => None,
         }
     };
@@ -181,10 +183,10 @@ fn show_implementations_action(db: &RootDatabase, def: Definition) -> Option<Hov
 
     match def {
         Definition::ModuleDef(it) => match it {
-            ModuleDef::Adt(Adt::Struct(it)) => Some(to_action(it.to_nav(db))),
-            ModuleDef::Adt(Adt::Union(it)) => Some(to_action(it.to_nav(db))),
-            ModuleDef::Adt(Adt::Enum(it)) => Some(to_action(it.to_nav(db))),
-            ModuleDef::Trait(it) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Struct(it)) => Some(to_action(it.try_to_nav(db)?)),
+            ModuleDef::Adt(Adt::Union(it)) => Some(to_action(it.try_to_nav(db)?)),
+            ModuleDef::Adt(Adt::Enum(it)) => Some(to_action(it.try_to_nav(db)?)),
+            ModuleDef::Trait(it) => Some(to_action(it.try_to_nav(db)?)),
             _ => None,
         },
         _ => None,
@@ -204,7 +206,8 @@ fn runnable_action(
                 _ => None,
             },
             ModuleDef::Function(it) => {
-                let src = it.source(sema.db);
+                #[allow(deprecated)]
+                let src = it.source(sema.db)?;
                 if src.file_id != file_id.into() {
                     mark::hit!(hover_macro_generated_struct_fn_doc_comment);
                     mark::hit!(hover_macro_generated_struct_fn_doc_attr);
@@ -324,17 +327,12 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
     let mod_path = definition_mod_path(db, &def);
     return match def {
         Definition::Macro(it) => {
-            // FIXME: Currently proc-macro do not have ast-node,
-            // such that it does not have source
-            // more discussion: https://github.com/rust-analyzer/rust-analyzer/issues/6913
-            if it.is_proc_macro() {
-                return None;
-            }
-            let label = macro_label(&it.source(db).value);
+            let label = macro_label(&it.source(db)?.value);
             from_def_source_labeled(db, it, Some(label), mod_path)
         }
         Definition::Field(def) => {
-            let src = def.source(db).value;
+            #[allow(deprecated)]
+            let src = def.source(db)?.value;
             if let FieldSource::Named(it) = src {
                 from_def_source_labeled(db, def, it.short_label(), mod_path)
             } else {
@@ -360,9 +358,9 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
             ModuleDef::Static(it) => from_def_source(db, it, mod_path),
             ModuleDef::Trait(it) => from_def_source(db, it, mod_path),
             ModuleDef::TypeAlias(it) => from_def_source(db, it, mod_path),
-            ModuleDef::BuiltinType(it) => return Some(it.to_string().into()),
+            ModuleDef::BuiltinType(it) => Some(Markup::fenced_block(&it)),
         },
-        Definition::Local(it) => return Some(Markup::fenced_block(&it.ty(db).display(db))),
+        Definition::Local(it) => Some(Markup::fenced_block(&it.ty(db).display(db))),
         Definition::SelfType(impl_def) => {
             impl_def.target_ty(db).as_adt().and_then(|adt| match adt {
                 Adt::Struct(it) => from_def_source(db, it, mod_path),
@@ -370,7 +368,9 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
                 Adt::Enum(it) => from_def_source(db, it, mod_path),
             })
         }
-        Definition::TypeParam(_) | Definition::LifetimeParam(_) | Definition::Label(_) => {
+        Definition::Label(it) => Some(Markup::fenced_block(&it.name(db))),
+        Definition::LifetimeParam(it) => Some(Markup::fenced_block(&it.name(db))),
+        Definition::TypeParam(_) | Definition::ConstParam(_) => {
             // FIXME: Hover for generic param
             None
         }
@@ -381,7 +381,8 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
         D: HasSource<Ast = A> + HasAttrs + Copy,
         A: ShortLabel,
     {
-        let short_label = def.source(db).value.short_label();
+        #[allow(deprecated)]
+        let short_label = def.source(db)?.value.short_label();
         from_def_source_labeled(db, def, short_label, mod_path)
     }
 
@@ -403,7 +404,7 @@ fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
     return tokens.max_by_key(priority);
     fn priority(n: &SyntaxToken) -> usize {
         match n.kind() {
-            IDENT | INT_NUMBER => 3,
+            IDENT | INT_NUMBER | LIFETIME_IDENT => 3,
             T!['('] | T![')'] => 2,
             kind if kind.is_trivia() => 0,
             _ => 1,
@@ -1169,7 +1170,10 @@ fn f() { fo<|>o!(); }
             r#"struct TS(String, i32<|>);"#,
             expect![[r#"
                 *i32*
+
+                ```rust
                 i32
+                ```
             "#]],
         )
     }
@@ -3221,4 +3225,36 @@ fn no_hover() {
 "#,
         );
     }
+
+    #[test]
+    fn hover_label() {
+        check(
+            r#"
+fn foo() {
+    'label<|>: loop {}
+}
+"#,
+            expect![[r#"
+            *'label*
+
+            ```rust
+            'label
+            ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_lifetime() {
+        check(
+            r#"fn foo<'lifetime>(_: &'lifetime<|> ()) {}"#,
+            expect![[r#"
+            *'lifetime*
+
+            ```rust
+            'lifetime
+            ```
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index b3331f03f..a450794f3 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -31,6 +31,7 @@ mod folding_ranges;
 mod goto_definition;
 mod goto_implementation;
 mod goto_type_definition;
+mod view_hir;
 mod hover;
 mod inlay_hints;
 mod join_lines;
@@ -271,6 +272,10 @@ impl Analysis {
         self.with_db(|db| syntax_tree::syntax_tree(&db, file_id, text_range))
     }
 
+    pub fn view_hir(&self, position: FilePosition) -> Cancelable<String> {
+        self.with_db(|db| view_hir::view_hir(&db, position))
+    }
+
     pub fn expand_macro(&self, position: FilePosition) -> Cancelable<Option<ExpandedMacro>> {
         self.with_db(|db| expand_macro::expand_macro(db, position))
     }
diff --git a/crates/ide/src/references.rs b/crates/ide/src/references.rs
index 21b2d7ca1..fa58fc319 100644
--- a/crates/ide/src/references.rs
+++ b/crates/ide/src/references.rs
@@ -1144,4 +1144,20 @@ fn foo<'a>() -> &'a () {
             "#]],
         );
     }
+
+    #[test]
+    fn test_find_const_param() {
+        check(
+            r#"
+fn foo<const FOO<|>: usize>() -> usize {
+    FOO
+}
+"#,
+            expect![[r#"
+                FOO ConstParam FileId(0) 7..23 13..16 Other
+
+                FileId(0) 42..45 Other
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
index 891183266..c893afc7c 100644
--- a/crates/ide/src/runnables.rs
+++ b/crates/ide/src/runnables.rs
@@ -230,7 +230,7 @@ impl TestAttr {
 
 const RUSTDOC_FENCE: &str = "```";
 const RUSTDOC_CODE_BLOCK_ATTRIBUTES_RUNNABLE: &[&str] =
-    &["", "rust", "should_panic", "edition2015", "edition2018"];
+    &["", "rust", "should_panic", "edition2015", "edition2018", "edition2021"];
 
 fn has_runnable_doc_test(attrs: &hir::Attrs) -> bool {
     attrs.docs().map_or(false, |doc| {
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index 5ad96581b..ba0085244 100644
--- a/crates/ide/src/syntax_highlighting.rs
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -819,6 +819,7 @@ fn highlight_def(db: &RootDatabase, def: Definition) -> Highlight {
         },
         Definition::SelfType(_) => HighlightTag::Symbol(SymbolKind::Impl),
         Definition::TypeParam(_) => HighlightTag::Symbol(SymbolKind::TypeParam),
+        Definition::ConstParam(_) => HighlightTag::Symbol(SymbolKind::ConstParam),
         Definition::Local(local) => {
             let tag = if local.is_param(db) {
                 HighlightTag::Symbol(SymbolKind::ValueParam)
diff --git a/crates/ide/src/syntax_highlighting/injection.rs b/crates/ide/src/syntax_highlighting/injection.rs
index 9eb184c74..6cbd683c6 100644
--- a/crates/ide/src/syntax_highlighting/injection.rs
+++ b/crates/ide/src/syntax_highlighting/injection.rs
@@ -54,8 +54,17 @@ pub(super) fn highlight_injection(
 type RangesMap = BTreeMap<TextSize, TextSize>;
 
 const RUSTDOC_FENCE: &'static str = "```";
-const RUSTDOC_FENCE_TOKENS: &[&'static str] =
-    &["", "rust", "should_panic", "ignore", "no_run", "compile_fail", "edition2015", "edition2018"];
+const RUSTDOC_FENCE_TOKENS: &[&'static str] = &[
+    "",
+    "rust",
+    "should_panic",
+    "ignore",
+    "no_run",
+    "compile_fail",
+    "edition2015",
+    "edition2018",
+    "edition2021",
+];
 
 /// Extracts Rust code from documentation comments as well as a mapping from
 /// the extracted source code back to the original source ranges.
diff --git a/crates/ide/src/syntax_highlighting/tags.rs b/crates/ide/src/syntax_highlighting/tags.rs
index 2a6cc0cab..8b8867079 100644
--- a/crates/ide/src/syntax_highlighting/tags.rs
+++ b/crates/ide/src/syntax_highlighting/tags.rs
@@ -77,6 +77,7 @@ impl HighlightTag {
                 SymbolKind::Function => "function",
                 SymbolKind::TypeAlias => "type_alias",
                 SymbolKind::TypeParam => "type_param",
+                SymbolKind::ConstParam => "const_param",
                 SymbolKind::LifetimeParam => "lifetime",
                 SymbolKind::Macro => "macro",
                 SymbolKind::Local => "variable",
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index 72ff9dd40..02270b077 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -118,6 +118,10 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="keyword control">loop</span> <span class="punctuation">{</span><span class="punctuation">}</span>
 <span class="punctuation">}</span>
 
+<span class="keyword">fn</span> <span class="function declaration">const_param</span><span class="punctuation">&lt;</span><span class="keyword">const</span> <span class="const_param declaration">FOO</span><span class="punctuation">:</span> <span class="builtin_type">usize</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">usize</span> <span class="punctuation">{</span>
+    <span class="const_param">FOO</span>
+<span class="punctuation">}</span>
+
 <span class="keyword">use</span> <span class="module">ops</span><span class="operator">::</span><span class="trait">Fn</span><span class="punctuation">;</span>
 <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">&lt;</span><span class="type_param declaration">F</span><span class="punctuation">:</span> <span class="trait">Fn</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="value_param declaration callable">f</span><span class="punctuation">:</span> <span class="type_param">F</span><span class="punctuation">)</span> <span class="punctuation">{</span>
     <span class="value_param callable">f</span><span class="punctuation">(</span><span class="punctuation">)</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index e0df0d2b5..30b5b648e 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -91,6 +91,10 @@ fn never() -> ! {
     loop {}
 }
 
+fn const_param<const FOO: usize>() -> usize {
+    FOO
+}
+
 use ops::Fn;
 fn baz<F: Fn() -> ()>(f: F) {
     f()
diff --git a/crates/ide/src/view_hir.rs b/crates/ide/src/view_hir.rs
new file mode 100644
index 000000000..cfcfb7cfb
--- /dev/null
+++ b/crates/ide/src/view_hir.rs
@@ -0,0 +1,25 @@
+use hir::{Function, Semantics};
+use ide_db::base_db::FilePosition;
+use ide_db::RootDatabase;
+use syntax::{algo::find_node_at_offset, ast, AstNode};
+
+// Feature: View Hir
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: View Hir**
+// |===
+pub(crate) fn view_hir(db: &RootDatabase, position: FilePosition) -> String {
+    body_hir(db, position).unwrap_or("Not inside a function body".to_string())
+}
+
+fn body_hir(db: &RootDatabase, position: FilePosition) -> Option<String> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(position.file_id);
+
+    let function = find_node_at_offset::<ast::Fn>(source_file.syntax(), position.offset)?;
+
+    let function: Function = sema.to_def(&function)?;
+    Some(function.debug_hir(db))
+}
diff --git a/crates/ide_db/Cargo.toml b/crates/ide_db/Cargo.toml
index ebe53c8ee..d3d3dc688 100644
--- a/crates/ide_db/Cargo.toml
+++ b/crates/ide_db/Cargo.toml
@@ -32,4 +32,4 @@ test_utils = { path = "../test_utils", version = "0.0.0" }
 hir = { path = "../hir", version = "0.0.0" }
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/ide_db/src/defs.rs b/crates/ide_db/src/defs.rs
index d33a6cb86..cc5078bf0 100644
--- a/crates/ide_db/src/defs.rs
+++ b/crates/ide_db/src/defs.rs
@@ -6,8 +6,8 @@
 // FIXME: this badly needs rename/rewrite (matklad, 2020-02-06).
 
 use hir::{
-    db::HirDatabase, Crate, Field, HasVisibility, Impl, Label, LifetimeParam, Local, MacroDef,
-    Module, ModuleDef, Name, PathResolution, Semantics, TypeParam, Visibility,
+    db::HirDatabase, ConstParam, Crate, Field, HasVisibility, Impl, Label, LifetimeParam, Local,
+    MacroDef, Module, ModuleDef, Name, PathResolution, Semantics, TypeParam, Visibility,
 };
 use syntax::{
     ast::{self, AstNode},
@@ -26,6 +26,7 @@ pub enum Definition {
     Local(Local),
     TypeParam(TypeParam),
     LifetimeParam(LifetimeParam),
+    ConstParam(ConstParam),
     Label(Label),
 }
 
@@ -39,6 +40,7 @@ impl Definition {
             Definition::Local(it) => Some(it.module(db)),
             Definition::TypeParam(it) => Some(it.module(db)),
             Definition::LifetimeParam(it) => Some(it.module(db)),
+            Definition::ConstParam(it) => Some(it.module(db)),
             Definition::Label(it) => Some(it.module(db)),
         }
     }
@@ -52,6 +54,7 @@ impl Definition {
             Definition::Local(_) => None,
             Definition::TypeParam(_) => None,
             Definition::LifetimeParam(_) => None,
+            Definition::ConstParam(_) => None,
             Definition::Label(_) => None,
         }
     }
@@ -79,6 +82,7 @@ impl Definition {
             Definition::Local(it) => it.name(db)?,
             Definition::TypeParam(it) => it.name(db),
             Definition::LifetimeParam(it) => it.name(db),
+            Definition::ConstParam(it) => it.name(db),
             Definition::Label(it) => it.name(db),
         };
         Some(name)
@@ -233,6 +237,10 @@ impl NameClass {
                     let def = sema.to_def(&it)?;
                     Some(NameClass::Definition(Definition::TypeParam(def)))
                 },
+                ast::ConstParam(it) => {
+                    let def = sema.to_def(&it)?;
+                    Some(NameClass::Definition(Definition::ConstParam(def)))
+                },
                 _ => None,
             }
         }
@@ -417,6 +425,7 @@ impl From<PathResolution> for Definition {
             PathResolution::TypeParam(par) => Definition::TypeParam(par),
             PathResolution::Macro(def) => Definition::Macro(def),
             PathResolution::SelfType(impl_def) => Definition::SelfType(impl_def),
+            PathResolution::ConstParam(par) => Definition::ConstParam(par),
         }
     }
 }
diff --git a/crates/ide_db/src/search.rs b/crates/ide_db/src/search.rs
index ff10f71c3..436c59d2c 100644
--- a/crates/ide_db/src/search.rs
+++ b/crates/ide_db/src/search.rs
@@ -121,31 +121,56 @@ impl Definition {
 
         if let Definition::Local(var) = self {
             let range = match var.parent(db) {
-                DefWithBody::Function(f) => f.source(db).value.syntax().text_range(),
-                DefWithBody::Const(c) => c.source(db).value.syntax().text_range(),
-                DefWithBody::Static(s) => s.source(db).value.syntax().text_range(),
+                DefWithBody::Function(f) => {
+                    f.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
+                DefWithBody::Const(c) => {
+                    c.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
+                DefWithBody::Static(s) => {
+                    s.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
             };
             let mut res = FxHashMap::default();
-            res.insert(file_id, Some(range));
+            res.insert(file_id, range);
             return SearchScope::new(res);
         }
 
         if let Definition::LifetimeParam(param) = self {
+            #[allow(deprecated)]
             let range = match param.parent(db) {
-                hir::GenericDef::Function(it) => it.source(db).value.syntax().text_range(),
+                hir::GenericDef::Function(it) => {
+                    it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
                 hir::GenericDef::Adt(it) => match it {
-                    hir::Adt::Struct(it) => it.source(db).value.syntax().text_range(),
-                    hir::Adt::Union(it) => it.source(db).value.syntax().text_range(),
-                    hir::Adt::Enum(it) => it.source(db).value.syntax().text_range(),
+                    hir::Adt::Struct(it) => {
+                        it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                    }
+                    hir::Adt::Union(it) => {
+                        it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                    }
+                    hir::Adt::Enum(it) => {
+                        it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                    }
                 },
-                hir::GenericDef::Trait(it) => it.source(db).value.syntax().text_range(),
-                hir::GenericDef::TypeAlias(it) => it.source(db).value.syntax().text_range(),
-                hir::GenericDef::Impl(it) => it.source(db).value.syntax().text_range(),
-                hir::GenericDef::Variant(it) => it.source(db).value.syntax().text_range(),
-                hir::GenericDef::Const(it) => it.source(db).value.syntax().text_range(),
+                hir::GenericDef::Trait(it) => {
+                    it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
+                hir::GenericDef::TypeAlias(it) => {
+                    it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
+                hir::GenericDef::Impl(it) => {
+                    it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
+                hir::GenericDef::Variant(it) => {
+                    it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
+                hir::GenericDef::Const(it) => {
+                    it.source(db).and_then(|src| Some(src.value.syntax().text_range()))
+                }
             };
             let mut res = FxHashMap::default();
-            res.insert(file_id, Some(range));
+            res.insert(file_id, range);
             return SearchScope::new(res);
         }
 
diff --git a/crates/proc_macro_api/src/msg.rs b/crates/proc_macro_api/src/msg.rs
index f84ebdbc5..4cd572101 100644
--- a/crates/proc_macro_api/src/msg.rs
+++ b/crates/proc_macro_api/src/msg.rs
@@ -58,7 +58,13 @@ pub trait Message: Serialize + DeserializeOwned {
     fn read(inp: &mut impl BufRead) -> io::Result<Option<Self>> {
         Ok(match read_json(inp)? {
             None => None,
-            Some(text) => Some(serde_json::from_str(&text)?),
+            Some(text) => {
+                let mut deserializer = serde_json::Deserializer::from_str(&text);
+                // Note that some proc-macro generate very deep syntax tree
+                // We have to disable the current limit of serde here
+                deserializer.disable_recursion_limit();
+                Some(Self::deserialize(&mut deserializer)?)
+            }
         })
     }
     fn write(self, out: &mut impl Write) -> io::Result<()> {
diff --git a/crates/proc_macro_api/src/process.rs b/crates/proc_macro_api/src/process.rs
index d68723ada..6d6ab8888 100644
--- a/crates/proc_macro_api/src/process.rs
+++ b/crates/proc_macro_api/src/process.rs
@@ -92,10 +92,11 @@ fn client_loop(task_rx: Receiver<Task>, mut process: Process) {
     for Task { req, result_tx } in task_rx {
         match send_request(&mut stdin, &mut stdout, req) {
             Ok(res) => result_tx.send(res).unwrap(),
-            Err(_err) => {
+            Err(err) => {
                 log::error!(
-                    "proc macro server crashed, server process state: {:?}",
-                    process.child.try_wait()
+                    "proc macro server crashed, server process state: {:?}, server request error: {:?}",
+                    process.child.try_wait(),
+                    err
                 );
                 let res = Response::Error(ResponseError {
                     code: ErrorCode::ServerErrorEnd,
diff --git a/crates/project_model/src/project_json.rs b/crates/project_model/src/project_json.rs
index aab279223..af884eb84 100644
--- a/crates/project_model/src/project_json.rs
+++ b/crates/project_model/src/project_json.rs
@@ -139,6 +139,8 @@ enum EditionData {
     Edition2015,
     #[serde(rename = "2018")]
     Edition2018,
+    #[serde(rename = "2021")]
+    Edition2021,
 }
 
 impl From<EditionData> for Edition {
@@ -146,6 +148,7 @@ impl From<EditionData> for Edition {
         match data {
             EditionData::Edition2015 => Edition::Edition2015,
             EditionData::Edition2018 => Edition::Edition2018,
+            EditionData::Edition2021 => Edition::Edition2021,
         }
     }
 }
diff --git a/crates/rust-analyzer/Cargo.toml b/crates/rust-analyzer/Cargo.toml
index 0a63593fb..af7b86ead 100644
--- a/crates/rust-analyzer/Cargo.toml
+++ b/crates/rust-analyzer/Cargo.toml
@@ -62,7 +62,7 @@ proc_macro_srv = { path = "../proc_macro_srv", version = "0.0.0" }
 winapi = "0.3.8"
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
 test_utils = { path = "../test_utils" }
 mbe = { path = "../mbe" }
 tt = { path = "../tt" }
diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index a23fb7a33..9445aec07 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -161,11 +161,12 @@ impl AnalysisStatsCmd {
             }
             let mut msg = format!("processing: {}", full_name);
             if verbosity.is_verbose() {
-                let src = f.source(db);
-                let original_file = src.file_id.original_file(db);
-                let path = vfs.file_path(original_file);
-                let syntax_range = src.value.syntax().text_range();
-                format_to!(msg, " ({} {:?})", path, syntax_range);
+                if let Some(src) = f.source(db) {
+                    let original_file = src.file_id.original_file(db);
+                    let path = vfs.file_path(original_file);
+                    let syntax_range = src.value.syntax().text_range();
+                    format_to!(msg, " ({} {:?})", path, syntax_range);
+                }
             }
             if verbosity.is_spammy() {
                 bar.println(msg.to_string());
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 1db5b4e7d..685a9fdf0 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -679,7 +679,7 @@ fn schema(fields: &[(&'static str, &'static str, &[&str], &str)]) -> serde_json:
     for ((f1, ..), (f2, ..)) in fields.iter().zip(&fields[1..]) {
         fn key(f: &str) -> &str {
             f.splitn(2, "_").next().unwrap()
-        };
+        }
         assert!(key(f1) <= key(f2), "wrong field order: {:?} {:?}", f1, f2);
     }
 
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 948cfc17c..dd486070b 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -105,6 +105,16 @@ pub(crate) fn handle_syntax_tree(
     Ok(res)
 }
 
+pub(crate) fn handle_view_hir(
+    snap: GlobalStateSnapshot,
+    params: lsp_types::TextDocumentPositionParams,
+) -> Result<String> {
+    let _p = profile::span("handle_view_hir");
+    let position = from_proto::file_position(&snap, params)?;
+    let res = snap.analysis.view_hir(position)?;
+    Ok(res)
+}
+
 pub(crate) fn handle_expand_macro(
     snap: GlobalStateSnapshot,
     params: lsp_ext::ExpandMacroParams,
diff --git a/crates/rust-analyzer/src/lsp_ext.rs b/crates/rust-analyzer/src/lsp_ext.rs
index 93ac45415..a85978737 100644
--- a/crates/rust-analyzer/src/lsp_ext.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -53,6 +53,14 @@ pub struct SyntaxTreeParams {
     pub range: Option<Range>,
 }
 
+pub enum ViewHir {}
+
+impl Request for ViewHir {
+    type Params = lsp_types::TextDocumentPositionParams;
+    type Result = String;
+    const METHOD: &'static str = "rust-analyzer/viewHir";
+}
+
 pub enum ExpandMacro {}
 
 impl Request for ExpandMacro {
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 5d55dc96e..8eca79f7e 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -443,6 +443,7 @@ impl GlobalState {
             .on_sync::<lsp_ext::MemoryUsage>(|s, p| handlers::handle_memory_usage(s, p))?
             .on::<lsp_ext::AnalyzerStatus>(handlers::handle_analyzer_status)
             .on::<lsp_ext::SyntaxTree>(handlers::handle_syntax_tree)
+            .on::<lsp_ext::ViewHir>(handlers::handle_view_hir)
             .on::<lsp_ext::ExpandMacro>(handlers::handle_expand_macro)
             .on::<lsp_ext::ParentModule>(handlers::handle_parent_module)
             .on::<lsp_ext::Runnables>(handlers::handle_runnables)
diff --git a/crates/rust-analyzer/src/markdown.rs b/crates/rust-analyzer/src/markdown.rs
index 968ea55f0..a49a58c00 100644
--- a/crates/rust-analyzer/src/markdown.rs
+++ b/crates/rust-analyzer/src/markdown.rs
@@ -1,8 +1,17 @@
 //! Transforms markdown
 
 const RUSTDOC_FENCE: &str = "```";
-const RUSTDOC_CODE_BLOCK_ATTRIBUTES_RUST_SPECIFIC: &[&str] =
-    &["", "rust", "should_panic", "ignore", "no_run", "compile_fail", "edition2015", "edition2018"];
+const RUSTDOC_CODE_BLOCK_ATTRIBUTES_RUST_SPECIFIC: &[&str] = &[
+    "",
+    "rust",
+    "should_panic",
+    "ignore",
+    "no_run",
+    "compile_fail",
+    "edition2015",
+    "edition2018",
+    "edition2021",
+];
 
 pub(crate) fn format_docs(src: &str) -> String {
     let mut processed_lines = Vec::new();
diff --git a/crates/rust-analyzer/src/semantic_tokens.rs b/crates/rust-analyzer/src/semantic_tokens.rs
index c2f6a655d..5c4366f16 100644
--- a/crates/rust-analyzer/src/semantic_tokens.rs
+++ b/crates/rust-analyzer/src/semantic_tokens.rs
@@ -44,6 +44,7 @@ define_semantic_token_types![
     (ESCAPE_SEQUENCE, "escapeSequence"),
     (FORMAT_SPECIFIER, "formatSpecifier"),
     (GENERIC, "generic"),
+    (CONST_PARAMETER, "constParameter"),
     (LIFETIME, "lifetime"),
     (LABEL, "label"),
     (PUNCTUATION, "punctuation"),
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 1a38e79f0..999b18351 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -42,6 +42,7 @@ pub(crate) fn symbol_kind(symbol_kind: SymbolKind) -> lsp_types::SymbolKind {
         SymbolKind::Field => lsp_types::SymbolKind::Field,
         SymbolKind::Static => lsp_types::SymbolKind::Constant,
         SymbolKind::Const => lsp_types::SymbolKind::Constant,
+        SymbolKind::ConstParam => lsp_types::SymbolKind::Constant,
         SymbolKind::Impl => lsp_types::SymbolKind::Object,
         SymbolKind::Local
         | SymbolKind::SelfParam
@@ -378,6 +379,7 @@ fn semantic_token_type_and_modifiers(
             SymbolKind::Impl => lsp_types::SemanticTokenType::TYPE,
             SymbolKind::Field => lsp_types::SemanticTokenType::PROPERTY,
             SymbolKind::TypeParam => lsp_types::SemanticTokenType::TYPE_PARAMETER,
+            SymbolKind::ConstParam => semantic_tokens::CONST_PARAMETER,
             SymbolKind::LifetimeParam => semantic_tokens::LIFETIME,
             SymbolKind::Label => semantic_tokens::LABEL,
             SymbolKind::ValueParam => lsp_types::SemanticTokenType::PARAMETER,
diff --git a/crates/ssr/Cargo.toml b/crates/ssr/Cargo.toml
index 339eda86a..cc8136d22 100644
--- a/crates/ssr/Cargo.toml
+++ b/crates/ssr/Cargo.toml
@@ -21,4 +21,4 @@ hir = { path = "../hir", version = "0.0.0" }
 test_utils = { path = "../test_utils", version = "0.0.0" }
 
 [dev-dependencies]
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index 5d8389ade..181077944 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -33,4 +33,4 @@ profile = { path = "../profile", version = "0.0.0" }
 [dev-dependencies]
 walkdir = "2.3.1"
 rayon = "1"
-expect-test = "1.0"
+expect-test = "1.1"
diff --git a/crates/syntax/src/ast/edit.rs b/crates/syntax/src/ast/edit.rs
index 77233ab31..824ebf41c 100644
--- a/crates/syntax/src/ast/edit.rs
+++ b/crates/syntax/src/ast/edit.rs
@@ -220,7 +220,7 @@ impl ast::RecordExprFieldList {
                     InsertPosition::After($anchor.syntax().clone().into())
                 }
             };
-        };
+        }
 
         let position = match position {
             InsertPosition::First => after_l_curly!(),
@@ -533,7 +533,7 @@ impl ast::GenericParamList {
                     InsertPosition::After($anchor.syntax().clone().into())
                 }
             };
-        };
+        }
 
         let position = match self.generic_params().last() {
             Some(it) => after_field!(it),
diff --git a/docs/dev/README.md b/docs/dev/README.md
index 4a2f9feb3..55527bab0 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -227,6 +227,8 @@ There are also two VS Code commands which might be of interest:
 
 * `Rust Analyzer: Syntax Tree` shows syntax tree of the current file/selection.
 
+* `Rust Analyzer: View Hir` shows the HIR expressions within the function containing the cursor.
+
   You can hover over syntax nodes in the opened text file to see the appropriate
   rust code that it refers to and the rust editor will also highlight the proper
   text range.
diff --git a/docs/dev/lsp-extensions.md b/docs/dev/lsp-extensions.md
index 8c01db07c..78d86f060 100644
--- a/docs/dev/lsp-extensions.md
+++ b/docs/dev/lsp-extensions.md
@@ -1,5 +1,5 @@
 <!---
-lsp_ext.rs hash: 203fdf79b21b5987
+lsp_ext.rs hash: 91f2c62457e0a20f
 
 If you need to change the above hash to make the test pass, please check if you
 need to adjust this doc as well and ping this  issue:
@@ -449,6 +449,17 @@ interface SyntaxTeeParams {
 Returns textual representation of a parse tree for the file/selected region.
 Primarily for debugging, but very useful for all people working on rust-analyzer itself.
 
+## View Hir
+
+**Method:** `rust-analyzer/viewHir`
+
+**Request:** `TextDocumentPositionParams`
+
+**Response:** `string`
+
+Returns a textual representation of the HIR of the function containing the cursor.
+For debugging or when working on rust-analyzer itself.
+
 ## Expand Macro
 
 **Method:** `rust-analyzer/expandMacro`
diff --git a/docs/user/manual.adoc b/docs/user/manual.adoc
index 8ed7b041f..266baffa1 100644
--- a/docs/user/manual.adoc
+++ b/docs/user/manual.adoc
@@ -342,7 +342,7 @@ interface Crate {
     /// Path to the root module of the crate.
     root_module: string;
     /// Edition of the crate.
-    edition: "2015" | "2018";
+    edition: "2015" | "2018" | "2021";
     /// Dependencies
     deps: Dep[];
     /// Should this crate be treated as a member of current "workspace".
diff --git a/editors/code/package.json b/editors/code/package.json
index 587f11b90..3e55a3523 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -104,6 +104,11 @@
                 "category": "Rust Analyzer"
             },
             {
+                "command": "rust-analyzer.viewHir",
+                "title": "View Hir",
+                "category": "Rust Analyzer"
+            },
+            {
                 "command": "rust-analyzer.expandMacro",
                 "title": "Expand macro recursively",
                 "category": "Rust Analyzer"
@@ -1007,6 +1012,10 @@
                     "when": "inRustProject"
                 },
                 {
+                    "command": "rust-analyzer.viewHir",
+                    "when": "inRustProject"
+                },
+                {
                     "command": "rust-analyzer.expandMacro",
                     "when": "inRustProject"
                 },
diff --git a/editors/code/src/commands.ts b/editors/code/src/commands.ts
index b12e134ca..c1c9f9754 100644
--- a/editors/code/src/commands.ts
+++ b/editors/code/src/commands.ts
@@ -340,6 +340,61 @@ export function syntaxTree(ctx: Ctx): Cmd {
     };
 }
 
+// Opens the virtual file that will show the HIR of the function containing the cursor position
+//
+// The contents of the file come from the `TextDocumentContentProvider`
+export function viewHir(ctx: Ctx): Cmd {
+    const tdcp = new class implements vscode.TextDocumentContentProvider {
+        readonly uri = vscode.Uri.parse('rust-analyzer://viewHir/hir.txt');
+        readonly eventEmitter = new vscode.EventEmitter<vscode.Uri>();
+        constructor() {
+            vscode.workspace.onDidChangeTextDocument(this.onDidChangeTextDocument, this, ctx.subscriptions);
+            vscode.window.onDidChangeActiveTextEditor(this.onDidChangeActiveTextEditor, this, ctx.subscriptions);
+        }
+
+        private onDidChangeTextDocument(event: vscode.TextDocumentChangeEvent) {
+            if (isRustDocument(event.document)) {
+                // We need to order this after language server updates, but there's no API for that.
+                // Hence, good old sleep().
+                void sleep(10).then(() => this.eventEmitter.fire(this.uri));
+            }
+        }
+        private onDidChangeActiveTextEditor(editor: vscode.TextEditor | undefined) {
+            if (editor && isRustEditor(editor)) {
+                this.eventEmitter.fire(this.uri);
+            }
+        }
+
+        provideTextDocumentContent(_uri: vscode.Uri, ct: vscode.CancellationToken): vscode.ProviderResult<string> {
+            const rustEditor = ctx.activeRustEditor;
+            const client = ctx.client;
+            if (!rustEditor || !client) return '';
+
+            const params = {
+                textDocument: client.code2ProtocolConverter.asTextDocumentIdentifier(rustEditor.document),
+                position: client.code2ProtocolConverter.asPosition(
+                    rustEditor.selection.active,
+                ),
+            };
+            return client.sendRequest(ra.viewHir, params, ct);
+        }
+
+        get onDidChange(): vscode.Event<vscode.Uri> {
+            return this.eventEmitter.event;
+        }
+    };
+
+    ctx.pushCleanup(vscode.workspace.registerTextDocumentContentProvider('rust-analyzer', tdcp));
+
+    return async () => {
+        const document = await vscode.workspace.openTextDocument(tdcp.uri);
+        tdcp.eventEmitter.fire(tdcp.uri);
+        void await vscode.window.showTextDocument(document, {
+            viewColumn: vscode.ViewColumn.Two,
+            preserveFocus: true
+        });
+    };
+}
 
 // Opens the virtual file that will show the syntax tree
 //
diff --git a/editors/code/src/lsp_ext.ts b/editors/code/src/lsp_ext.ts
index 5e877ce65..d21a3db86 100644
--- a/editors/code/src/lsp_ext.ts
+++ b/editors/code/src/lsp_ext.ts
@@ -24,6 +24,7 @@ export interface SyntaxTreeParams {
 }
 export const syntaxTree = new lc.RequestType<SyntaxTreeParams, string, void>("rust-analyzer/syntaxTree");
 
+export const viewHir = new lc.RequestType<lc.TextDocumentPositionParams, string, void>("rust-analyzer/viewHir");
 
 export interface ExpandMacroParams {
     textDocument: lc.TextDocumentIdentifier;
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index 282240d84..60907dfd4 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -105,6 +105,7 @@ async function tryActivate(context: vscode.ExtensionContext) {
     ctx.registerCommand('joinLines', commands.joinLines);
     ctx.registerCommand('parentModule', commands.parentModule);
     ctx.registerCommand('syntaxTree', commands.syntaxTree);
+    ctx.registerCommand('viewHir', commands.viewHir);
     ctx.registerCommand('expandMacro', commands.expandMacro);
     ctx.registerCommand('run', commands.run);
     ctx.registerCommand('debug', commands.debug);
diff --git a/xtask/src/dist.rs b/xtask/src/dist.rs
index d59b88131..6bc34106b 100644
--- a/xtask/src/dist.rs
+++ b/xtask/src/dist.rs
@@ -63,8 +63,7 @@ fn dist_server() -> Result<()> {
         env::set_var("CC", "clang");
     }
 
-    let toolchain = toolchain(&target);
-    cmd!("cargo +{toolchain} build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --target {target} --release").run()?;
+    cmd!("cargo build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --target {target} --release").run()?;
 
     let suffix = exe_suffix(&target);
     let src =
@@ -118,13 +117,6 @@ fn exe_suffix(target: &str) -> String {
     }
 }
 
-fn toolchain(target: &str) -> String {
-    match target {
-        "aarch64-apple-darwin" => "beta".to_string(),
-        _ => "stable".to_string(),
-    }
-}
-
 fn gzip(src_path: &Path, dest_path: &Path) -> Result<()> {
     let mut encoder = GzEncoder::new(File::create(dest_path)?, Compression::best());
     let mut input = io::BufReader::new(File::open(src_path)?);
diff --git a/xtask/tests/tidy.rs b/xtask/tests/tidy.rs
index 6bfa922e6..d1ffb70ad 100644
--- a/xtask/tests/tidy.rs
+++ b/xtask/tests/tidy.rs
@@ -139,7 +139,7 @@ fn deny_clippy(path: &PathBuf, text: &String) {
         return;
     }
 
-    if text.contains("[\u{61}llow(clippy") {
+    if text.contains("\u{61}llow(clippy") {
         panic!(
             "\n\nallowing lints is forbidden: {}.
 rust-analyzer intentionally doesn't check clippy on CI.