79 files changed, 1314 insertions, 314 deletions

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),