19 files changed, 582 insertions, 66 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 80e778bcf..2e052d267 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -960,6 +960,7 @@ name = "ra_hir"
 version = "0.1.0"
 dependencies = [
  "either",
+ "itertools",
  "log",
  "ra_db",
  "ra_hir_def",
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index 0555a0de7..266c4cff3 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -12,6 +12,8 @@ log = "0.4.8"
 rustc-hash = "1.1.0"
 either = "1.5.3"
 
+itertools = "0.8.2"
+
 ra_syntax = { path = "../ra_syntax" }
 ra_db = { path = "../ra_db" }
 ra_prof = { path = "../ra_prof" }
diff --git a/crates/ra_hir/src/semantics.rs b/crates/ra_hir/src/semantics.rs
index 965d185a4..3782a9984 100644
--- a/crates/ra_hir/src/semantics.rs
+++ b/crates/ra_hir/src/semantics.rs
@@ -6,7 +6,7 @@ use std::{cell::RefCell, fmt, iter::successors};
 
 use hir_def::{
     resolver::{self, HasResolver, Resolver},
-    TraitId,
+    AsMacroCall, TraitId,
 };
 use hir_expand::ExpansionInfo;
 use ra_db::{FileId, FileRange};
@@ -70,6 +70,20 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         Some(node)
     }
 
+    pub fn expand_hypothetical(
+        &self,
+        actual_macro_call: &ast::MacroCall,
+        hypothetical_args: &ast::TokenTree,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        let macro_call =
+            self.find_file(actual_macro_call.syntax().clone()).with_value(actual_macro_call);
+        let sa = self.analyze2(macro_call.map(|it| it.syntax()), None);
+        let macro_call_id = macro_call
+            .as_call_id(self.db, |path| sa.resolver.resolve_path_as_macro(self.db, &path))?;
+        hir_expand::db::expand_hypothetical(self.db, macro_call_id, hypothetical_args, token_to_map)
+    }
+
     pub fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
         let parent = token.parent();
         let parent = self.find_file(parent);
@@ -104,6 +118,25 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         node.ancestors_with_macros(self.db).map(|it| it.value)
     }
 
+    pub fn ancestors_at_offset_with_macros(
+        &self,
+        node: &SyntaxNode,
+        offset: TextUnit,
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
+        use itertools::Itertools;
+        node.token_at_offset(offset)
+            .map(|token| self.ancestors_with_macros(token.parent()))
+            .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
+    }
+
+    pub fn find_node_at_offset_with_macros<N: AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextUnit,
+    ) -> Option<N> {
+        self.ancestors_at_offset_with_macros(node, offset).find_map(N::cast)
+    }
+
     pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
         self.analyze(expr.syntax()).type_of(self.db, &expr)
     }
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index f3a84cacc..29dde3d80 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -72,6 +72,30 @@ pub trait AstDatabase: SourceDatabase {
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
 }
 
+/// This expands the given macro call, but with different arguments. This is
+/// used for completion, where we want to see what 'would happen' if we insert a
+/// token. The `token_to_map` mapped down into the expansion, with the mapped
+/// token returned.
+pub fn expand_hypothetical(
+    db: &impl AstDatabase,
+    actual_macro_call: MacroCallId,
+    hypothetical_args: &ra_syntax::ast::TokenTree,
+    token_to_map: ra_syntax::SyntaxToken,
+) -> Option<(SyntaxNode, ra_syntax::SyntaxToken)> {
+    let macro_file = MacroFile { macro_call_id: actual_macro_call };
+    let (tt, tmap_1) = mbe::syntax_node_to_token_tree(hypothetical_args.syntax()).unwrap();
+    let range =
+        token_to_map.text_range().checked_sub(hypothetical_args.syntax().text_range().start())?;
+    let token_id = tmap_1.token_by_range(range)?;
+    let macro_def = expander(db, actual_macro_call)?;
+    let (node, tmap_2) =
+        parse_macro_with_arg(db, macro_file, Some(std::sync::Arc::new((tt, tmap_1))))?;
+    let token_id = macro_def.0.map_id_down(token_id);
+    let range = tmap_2.range_by_token(token_id)?.by_kind(token_to_map.kind())?;
+    let token = ra_syntax::algo::find_covering_element(&node.syntax_node(), range).into_token()?;
+    Some((node.syntax_node(), token))
+}
+
 pub(crate) fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
     let map =
         db.parse_or_expand(file_id).map_or_else(AstIdMap::default, |it| AstIdMap::from_source(&it));
@@ -130,15 +154,42 @@ pub(crate) fn macro_expand(
     db: &dyn AstDatabase,
     id: MacroCallId,
 ) -> Result<Arc<tt::Subtree>, String> {
+    macro_expand_with_arg(db, id, None)
+}
+
+fn expander(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
+    let lazy_id = match id {
+        MacroCallId::LazyMacro(id) => id,
+        MacroCallId::EagerMacro(_id) => {
+            return None;
+        }
+    };
+
+    let loc = db.lookup_intern_macro(lazy_id);
+    let macro_rules = db.macro_def(loc.def)?;
+    Some(macro_rules)
+}
+
+fn macro_expand_with_arg(
+    db: &dyn AstDatabase,
+    id: MacroCallId,
+    arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
+) -> Result<Arc<tt::Subtree>, String> {
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
         MacroCallId::EagerMacro(id) => {
-            return Ok(db.lookup_intern_eager_expansion(id).subtree);
+            if arg.is_some() {
+                return Err(
+                    "hypothetical macro expansion not implemented for eager macro".to_owned()
+                );
+            } else {
+                return Ok(db.lookup_intern_eager_expansion(id).subtree);
+            }
         }
     };
 
     let loc = db.lookup_intern_macro(lazy_id);
-    let macro_arg = db.macro_arg(id).ok_or("Fail to args in to tt::TokenTree")?;
+    let macro_arg = arg.or_else(|| db.macro_arg(id)).ok_or("Fail to args in to tt::TokenTree")?;
 
     let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
     let tt = macro_rules.0.expand(db, lazy_id, &macro_arg.0).map_err(|err| format!("{:?}", err))?;
@@ -163,11 +214,23 @@ pub(crate) fn parse_macro(
     db: &dyn AstDatabase,
     macro_file: MacroFile,
 ) -> Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)> {
+    parse_macro_with_arg(db, macro_file, None)
+}
+
+pub fn parse_macro_with_arg(
+    db: &dyn AstDatabase,
+    macro_file: MacroFile,
+    arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
+) -> Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)> {
     let _p = profile("parse_macro_query");
 
     let macro_call_id = macro_file.macro_call_id;
-    let tt = db
-        .macro_expand(macro_call_id)
+    let expansion = if let Some(arg) = arg {
+        macro_expand_with_arg(db, macro_call_id, Some(arg))
+    } else {
+        db.macro_expand(macro_call_id)
+    };
+    let tt = expansion
         .map_err(|err| {
             // Note:
             // The final goal we would like to make all parse_macro success,
diff --git a/crates/ra_ide/src/completion/complete_dot.rs b/crates/ra_ide/src/completion/complete_dot.rs
index acada48ae..f275305e2 100644
--- a/crates/ra_ide/src/completion/complete_dot.rs
+++ b/crates/ra_ide/src/completion/complete_dot.rs
@@ -38,7 +38,7 @@ pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
 fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
     for receiver in receiver.autoderef(ctx.db) {
         for (field, ty) in receiver.fields(ctx.db) {
-            if ctx.module.map_or(false, |m| !field.is_visible_from(ctx.db, m)) {
+            if ctx.scope().module().map_or(false, |m| !field.is_visible_from(ctx.db, m)) {
                 // Skip private field. FIXME: If the definition location of the
                 // field is editable, we should show the completion
                 continue;
@@ -53,7 +53,7 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Ty
 }
 
 fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
-    if let Some(krate) = ctx.module.map(|it| it.krate()) {
+    if let Some(krate) = ctx.krate {
         let mut seen_methods = FxHashSet::default();
         let traits_in_scope = ctx.scope().traits_in_scope();
         receiver.iterate_method_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, func| {
@@ -620,4 +620,102 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn works_in_simple_macro_1() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(a.x<|>)
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [156; 157),
+                delete: [156; 157),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_recursive() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(a.x<|>)
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [156; 157),
+                delete: [156; 157),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_2() {
+        // this doesn't work yet because the macro doesn't expand without the token -- maybe it can be fixed with better recovery
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(a.<|>)
+                }
+                ",
+            ),
+            @r###"[]"###
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_recursive_1() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(m!(m!(a.x<|>)))
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [162; 163),
+                delete: [162; 163),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_keyword.rs b/crates/ra_ide/src/completion/complete_keyword.rs
index eb7cd9ac2..e1c0ffb1f 100644
--- a/crates/ra_ide/src/completion/complete_keyword.rs
+++ b/crates/ra_ide/src/completion/complete_keyword.rs
@@ -79,6 +79,7 @@ pub(super) fn complete_expr_keyword(acc: &mut Completions, ctx: &CompletionConte
 }
 
 fn is_in_loop_body(leaf: &SyntaxToken) -> bool {
+    // FIXME move this to CompletionContext and make it handle macros
     for node in leaf.parent().ancestors() {
         if node.kind() == FN_DEF || node.kind() == LAMBDA_EXPR {
             break;
diff --git a/crates/ra_ide/src/completion/complete_path.rs b/crates/ra_ide/src/completion/complete_path.rs
index d2c758571..3c4a70561 100644
--- a/crates/ra_ide/src/completion/complete_path.rs
+++ b/crates/ra_ide/src/completion/complete_path.rs
@@ -1,4 +1,4 @@
-//! Completion of paths, including when writing a single name.
+//! Completion of paths, i.e. `some::prefix::<|>`.
 
 use hir::{Adt, HasVisibility, PathResolution, ScopeDef};
 use ra_syntax::AstNode;
@@ -48,7 +48,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
             };
             // Iterate assoc types separately
             // FIXME: complete T::AssocType
-            let krate = ctx.module.map(|m| m.krate());
+            let krate = ctx.krate;
             if let Some(krate) = krate {
                 let traits_in_scope = ctx.scope().traits_in_scope();
                 ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
@@ -934,4 +934,37 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn completes_in_simple_macro_call() {
+        let completions = do_reference_completion(
+            r#"
+                macro_rules! m { ($e:expr) => { $e } }
+                fn main() { m!(self::f<|>); }
+                fn foo() {}
+            "#,
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "foo()",
+                source_range: [93; 94),
+                delete: [93; 94),
+                insert: "foo()$0",
+                kind: Function,
+                lookup: "foo",
+                detail: "fn foo()",
+            },
+            CompletionItem {
+                label: "main()",
+                source_range: [93; 94),
+                delete: [93; 94),
+                insert: "main()$0",
+                kind: Function,
+                lookup: "main",
+                detail: "fn main()",
+            },
+        ]
+        "###);
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_pattern.rs b/crates/ra_ide/src/completion/complete_pattern.rs
index c2c6ca002..fa8aeceda 100644
--- a/crates/ra_ide/src/completion/complete_pattern.rs
+++ b/crates/ra_ide/src/completion/complete_pattern.rs
@@ -86,4 +86,22 @@ mod tests {
         ]
         "###);
     }
+
+    #[test]
+    fn completes_in_simple_macro_call() {
+        // FIXME: doesn't work yet because of missing error recovery in macro expansion
+        let completions = complete(
+            r"
+            macro_rules! m { ($e:expr) => { $e } }
+            enum E { X }
+
+            fn foo() {
+               m!(match E::X {
+                   <|>
+               })
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"[]"###);
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_postfix.rs b/crates/ra_ide/src/completion/complete_postfix.rs
index 8a74f993a..65ecea125 100644
--- a/crates/ra_ide/src/completion/complete_postfix.rs
+++ b/crates/ra_ide/src/completion/complete_postfix.rs
@@ -67,8 +67,8 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
 
 fn postfix_snippet(ctx: &CompletionContext, label: &str, detail: &str, snippet: &str) -> Builder {
     let edit = {
-        let receiver_range =
-            ctx.dot_receiver.as_ref().expect("no receiver available").syntax().text_range();
+        let receiver_syntax = ctx.dot_receiver.as_ref().expect("no receiver available").syntax();
+        let receiver_range = ctx.sema.original_range(receiver_syntax).range;
         let delete_range = TextRange::from_to(receiver_range.start(), ctx.source_range().end());
         TextEdit::replace(delete_range, snippet.to_string())
     };
@@ -279,4 +279,65 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn works_in_simple_macro() {
+        assert_debug_snapshot!(
+            do_postfix_completion(
+                r#"
+                macro_rules! m { ($e:expr) => { $e } }
+                fn main() {
+                    let bar: u8 = 12;
+                    m!(bar.b<|>)
+                }
+                "#,
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "box",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "Box::new(bar)",
+                detail: "Box::new(expr)",
+            },
+            CompletionItem {
+                label: "dbg",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "dbg!(bar)",
+                detail: "dbg!(expr)",
+            },
+            CompletionItem {
+                label: "match",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "match bar {\n    ${1:_} => {$0\\},\n}",
+                detail: "match expr {}",
+            },
+            CompletionItem {
+                label: "not",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "!bar",
+                detail: "!expr",
+            },
+            CompletionItem {
+                label: "ref",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "&bar",
+                detail: "&expr",
+            },
+            CompletionItem {
+                label: "refm",
+                source_range: [149; 150),
+                delete: [145; 150),
+                insert: "&mut bar",
+                detail: "&mut expr",
+            },
+        ]
+        "###
+        );
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_record_literal.rs b/crates/ra_ide/src/completion/complete_record_literal.rs
index f98353d76..be6e4194f 100644
--- a/crates/ra_ide/src/completion/complete_record_literal.rs
+++ b/crates/ra_ide/src/completion/complete_record_literal.rs
@@ -153,4 +153,29 @@ mod tests {
         ]
         "###);
     }
+
+    #[test]
+    fn test_record_literal_field_in_simple_macro() {
+        let completions = complete(
+            r"
+            macro_rules! m { ($e:expr) => { $e } }
+            struct A { the_field: u32 }
+            fn foo() {
+               m!(A { the<|> })
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [137; 140),
+                delete: [137; 140),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###);
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_record_pattern.rs b/crates/ra_ide/src/completion/complete_record_pattern.rs
index 9bdeae49f..687c57d3e 100644
--- a/crates/ra_ide/src/completion/complete_record_pattern.rs
+++ b/crates/ra_ide/src/completion/complete_record_pattern.rs
@@ -87,4 +87,32 @@ mod tests {
         ]
         "###);
     }
+
+    #[test]
+    fn test_record_pattern_field_in_simple_macro() {
+        let completions = complete(
+            r"
+            macro_rules! m { ($e:expr) => { $e } }
+            struct S { foo: u32 }
+
+            fn process(f: S) {
+                m!(match f {
+                    S { f<|>: 92 } => (),
+                })
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "foo",
+                source_range: [171; 172),
+                delete: [171; 172),
+                insert: "foo",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###);
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_scope.rs b/crates/ra_ide/src/completion/complete_scope.rs
index 2b9a0e556..eb3c8cf1b 100644
--- a/crates/ra_ide/src/completion/complete_scope.rs
+++ b/crates/ra_ide/src/completion/complete_scope.rs
@@ -1,4 +1,4 @@
-//! FIXME: write short doc here
+//! Completion of names from the current scope, e.g. locals and imported items.
 
 use crate::completion::{CompletionContext, Completions};
 
@@ -797,4 +797,72 @@ mod tests {
         "###
         )
     }
+
+    #[test]
+    fn completes_in_simple_macro_1() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                fn quux(x: i32) {
+                    let y = 92;
+                    m!(<|>);
+                }
+                "
+            ),
+            @"[]"
+        );
+    }
+
+    #[test]
+    fn completes_in_simple_macro_2() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                fn quux(x: i32) {
+                    let y = 92;
+                    m!(x<|>);
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "m!",
+                source_range: [145; 146),
+                delete: [145; 146),
+                insert: "m!($0)",
+                kind: Macro,
+                detail: "macro_rules! m",
+            },
+            CompletionItem {
+                label: "quux(…)",
+                source_range: [145; 146),
+                delete: [145; 146),
+                insert: "quux(${1:x})$0",
+                kind: Function,
+                lookup: "quux",
+                detail: "fn quux(x: i32)",
+            },
+            CompletionItem {
+                label: "x",
+                source_range: [145; 146),
+                delete: [145; 146),
+                insert: "x",
+                kind: Binding,
+                detail: "i32",
+            },
+            CompletionItem {
+                label: "y",
+                source_range: [145; 146),
+                delete: [145; 146),
+                insert: "y",
+                kind: Binding,
+                detail: "i32",
+            },
+        ]
+        "###
+        );
+    }
 }
diff --git a/crates/ra_ide/src/completion/completion_context.rs b/crates/ra_ide/src/completion/completion_context.rs
index 9aa5a705d..40535c09e 100644
--- a/crates/ra_ide/src/completion/completion_context.rs
+++ b/crates/ra_ide/src/completion/completion_context.rs
@@ -5,7 +5,7 @@ use ra_db::SourceDatabase;
 use ra_ide_db::RootDatabase;
 use ra_syntax::{
     algo::{find_covering_element, find_node_at_offset},
-    ast, AstNode, SourceFile,
+    ast, AstNode,
     SyntaxKind::*,
     SyntaxNode, SyntaxToken, TextRange, TextUnit,
 };
@@ -20,8 +20,11 @@ pub(crate) struct CompletionContext<'a> {
     pub(super) sema: Semantics<'a, RootDatabase>,
     pub(super) db: &'a RootDatabase,
     pub(super) offset: TextUnit,
+    /// The token before the cursor, in the original file.
+    pub(super) original_token: SyntaxToken,
+    /// The token before the cursor, in the macro-expanded file.
     pub(super) token: SyntaxToken,
-    pub(super) module: Option<hir::Module>,
+    pub(super) krate: Option<hir::Crate>,
     pub(super) name_ref_syntax: Option<ast::NameRef>,
     pub(super) function_syntax: Option<ast::FnDef>,
     pub(super) use_item_syntax: Option<ast::UseItem>,
@@ -67,15 +70,20 @@ impl<'a> CompletionContext<'a> {
             let edit = AtomTextEdit::insert(position.offset, "intellijRulezz".to_string());
             parse.reparse(&edit).tree()
         };
+        let fake_ident_token =
+            file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 
-        let module = sema.to_module_def(position.file_id);
-        let token = original_file.syntax().token_at_offset(position.offset).left_biased()?;
+        let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
+        let original_token =
+            original_file.syntax().token_at_offset(position.offset).left_biased()?;
+        let token = sema.descend_into_macros(original_token.clone());
         let mut ctx = CompletionContext {
             sema,
             db,
+            original_token,
             token,
             offset: position.offset,
-            module,
+            krate,
             name_ref_syntax: None,
             function_syntax: None,
             use_item_syntax: None,
@@ -95,15 +103,57 @@ impl<'a> CompletionContext<'a> {
             has_type_args: false,
             dot_receiver_is_ambiguous_float_literal: false,
         };
-        ctx.fill(&original_file, file_with_fake_ident, position.offset);
+
+        let mut original_file = original_file.syntax().clone();
+        let mut hypothetical_file = file_with_fake_ident.syntax().clone();
+        let mut offset = position.offset;
+        let mut fake_ident_token = fake_ident_token;
+
+        // Are we inside a macro call?
+        while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
+            find_node_at_offset::<ast::MacroCall>(&original_file, offset),
+            find_node_at_offset::<ast::MacroCall>(&hypothetical_file, offset),
+        ) {
+            if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
+                != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
+            {
+                break;
+            }
+            let hypothetical_args = match macro_call_with_fake_ident.token_tree() {
+                Some(tt) => tt,
+                None => break,
+            };
+            if let (Some(actual_expansion), Some(hypothetical_expansion)) = (
+                ctx.sema.expand(&actual_macro_call),
+                ctx.sema.expand_hypothetical(
+                    &actual_macro_call,
+                    &hypothetical_args,
+                    fake_ident_token,
+                ),
+            ) {
+                let new_offset = hypothetical_expansion.1.text_range().start();
+                if new_offset >= actual_expansion.text_range().end() {
+                    break;
+                }
+                original_file = actual_expansion;
+                hypothetical_file = hypothetical_expansion.0;
+                fake_ident_token = hypothetical_expansion.1;
+                offset = new_offset;
+            } else {
+                break;
+            }
+        }
+
+        ctx.fill(&original_file, hypothetical_file, offset);
         Some(ctx)
     }
 
     // The range of the identifier that is being completed.
     pub(crate) fn source_range(&self) -> TextRange {
+        // check kind of macro-expanded token, but use range of original token
         match self.token.kind() {
             // workaroud when completion is triggered by trigger characters.
-            IDENT => self.token.text_range(),
+            IDENT => self.original_token.text_range(),
             _ => TextRange::offset_len(self.offset, 0.into()),
         }
     }
@@ -114,27 +164,24 @@ impl<'a> CompletionContext<'a> {
 
     fn fill(
         &mut self,
-        original_file: &ast::SourceFile,
-        file_with_fake_ident: ast::SourceFile,
+        original_file: &SyntaxNode,
+        file_with_fake_ident: SyntaxNode,
         offset: TextUnit,
     ) {
         // First, let's try to complete a reference to some declaration.
-        if let Some(name_ref) =
-            find_node_at_offset::<ast::NameRef>(file_with_fake_ident.syntax(), offset)
-        {
+        if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
             // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
             // See RFC#1685.
             if is_node::<ast::Param>(name_ref.syntax()) {
                 self.is_param = true;
                 return;
             }
-            self.classify_name_ref(original_file, name_ref);
+            self.classify_name_ref(original_file, name_ref, offset);
         }
 
         // Otherwise, see if this is a declaration. We can use heuristics to
         // suggest declaration names, see `CompletionKind::Magic`.
-        if let Some(name) = find_node_at_offset::<ast::Name>(file_with_fake_ident.syntax(), offset)
-        {
+        if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
             if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::BindPat::cast) {
                 let parent = bind_pat.syntax().parent();
                 if parent.clone().and_then(ast::MatchArm::cast).is_some()
@@ -148,23 +195,29 @@ impl<'a> CompletionContext<'a> {
                 return;
             }
             if name.syntax().ancestors().find_map(ast::RecordFieldPatList::cast).is_some() {
-                self.record_lit_pat = find_node_at_offset(original_file.syntax(), self.offset);
+                self.record_lit_pat =
+                    self.sema.find_node_at_offset_with_macros(&original_file, offset);
             }
         }
     }
 
-    fn classify_name_ref(&mut self, original_file: &SourceFile, name_ref: ast::NameRef) {
+    fn classify_name_ref(
+        &mut self,
+        original_file: &SyntaxNode,
+        name_ref: ast::NameRef,
+        offset: TextUnit,
+    ) {
         self.name_ref_syntax =
-            find_node_at_offset(original_file.syntax(), name_ref.syntax().text_range().start());
+            find_node_at_offset(&original_file, name_ref.syntax().text_range().start());
         let name_range = name_ref.syntax().text_range();
         if name_ref.syntax().parent().and_then(ast::RecordField::cast).is_some() {
-            self.record_lit_syntax = find_node_at_offset(original_file.syntax(), self.offset);
+            self.record_lit_syntax =
+                self.sema.find_node_at_offset_with_macros(&original_file, offset);
         }
 
         self.impl_def = self
-            .token
-            .parent()
-            .ancestors()
+            .sema
+            .ancestors_with_macros(self.token.parent())
             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
             .find_map(ast::ImplDef::cast);
 
@@ -183,12 +236,12 @@ impl<'a> CompletionContext<'a> {
             _ => (),
         }
 
-        self.use_item_syntax = self.token.parent().ancestors().find_map(ast::UseItem::cast);
+        self.use_item_syntax =
+            self.sema.ancestors_with_macros(self.token.parent()).find_map(ast::UseItem::cast);
 
         self.function_syntax = self
-            .token
-            .parent()
-            .ancestors()
+            .sema
+            .ancestors_with_macros(self.token.parent())
             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
             .find_map(ast::FnDef::cast);
 
@@ -242,7 +295,7 @@ impl<'a> CompletionContext<'a> {
 
                 if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
                     if let Some(if_expr) =
-                        find_node_at_offset::<ast::IfExpr>(original_file.syntax(), off)
+                        self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
                     {
                         if if_expr.syntax().text_range().end()
                             < name_ref.syntax().text_range().start()
@@ -259,7 +312,7 @@ impl<'a> CompletionContext<'a> {
             self.dot_receiver = field_expr
                 .expr()
                 .map(|e| e.syntax().text_range())
-                .and_then(|r| find_node_with_range(original_file.syntax(), r));
+                .and_then(|r| find_node_with_range(original_file, r));
             self.dot_receiver_is_ambiguous_float_literal =
                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
                     match l.kind() {
@@ -275,7 +328,7 @@ impl<'a> CompletionContext<'a> {
             self.dot_receiver = method_call_expr
                 .expr()
                 .map(|e| e.syntax().text_range())
-                .and_then(|r| find_node_with_range(original_file.syntax(), r));
+                .and_then(|r| find_node_with_range(original_file, r));
             self.is_call = true;
         }
     }
diff --git a/crates/ra_mbe/src/mbe_expander/matcher.rs b/crates/ra_mbe/src/mbe_expander/matcher.rs
index ffba03898..49c53183a 100644
--- a/crates/ra_mbe/src/mbe_expander/matcher.rs
+++ b/crates/ra_mbe/src/mbe_expander/matcher.rs
@@ -247,6 +247,7 @@ impl<'a> TtIter<'a> {
         ra_parser::parse_fragment(&mut src, &mut sink, fragment_kind);
 
         if !sink.cursor.is_root() || sink.error {
+            // FIXME better recovery in this case would help completion inside macros immensely
             return Err(());
         }
 
@@ -375,7 +376,8 @@ fn match_meta_var(kind: &str, input: &mut TtIter) -> Result<Option<Fragment>, Ex
             return Ok(Some(Fragment::Tokens(tt)));
         }
     };
-    let tt = input.expect_fragment(fragment).map_err(|()| err!())?;
+    let tt =
+        input.expect_fragment(fragment).map_err(|()| err!("fragment did not parse as {}", kind))?;
     let fragment = if kind == "expr" { Fragment::Ast(tt) } else { Fragment::Tokens(tt) };
     Ok(Some(fragment))
 }
diff --git a/docs/user/readme.adoc b/docs/user/readme.adoc
index f1386a8f9..e5843ed70 100644
--- a/docs/user/readme.adoc
+++ b/docs/user/readme.adoc
@@ -2,6 +2,13 @@
 :toc: preamble
 :sectanchors:
 :page-layout: post
+// https://gist.github.com/dcode/0cfbf2699a1fe9b46ff04c41721dda74#admonitions
+:tip-caption: :bulb:
+:note-caption: :information_source:
+:important-caption: :heavy_exclamation_mark:
+:caution-caption: :fire:
+:warning-caption: :warning:
+
 
 
 // Master copy of this document lives in the https://github.com/rust-analyzer/rust-analyzer repository
@@ -30,7 +37,7 @@ $ rustup component add rust-src
 
 === VS Code
 
-This the best supported editor at the moment.
+This is the best supported editor at the moment.
 rust-analyzer plugin for VS Code is maintained
 https://github.com/rust-analyzer/rust-analyzer/tree/master/editors/code[in tree].
 
@@ -40,6 +47,16 @@ By default, the plugin will prompt you to download the matching version of the s
 
 image::https://user-images.githubusercontent.com/9021944/75067008-17502500-54ba-11ea-835a-f92aac50e866.png[]
 
+[NOTE]
+====
+To disable this notification put the following to `settings.json`
+
+[source,json]
+----
+{ "rust-analyzer.updates.askBeforeDownload": false }
+----
+====
+
 The server binary is stored in `~/.config/Code/User/globalStorage/matklad.rust-analyzer`.
 
 Note that we only support the latest version of VS Code.
diff --git a/editors/code/package.json b/editors/code/package.json
index fd44d2bd5..7a4a93e30 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -219,6 +219,11 @@
                         }
                     }
                 },
+                "rust-analyzer.updates.askBeforeDownload": {
+                    "type": "boolean",
+                    "default": true,
+                    "description": "Whether to ask for permission before downloading any files from the Internet"
+                },
                 "rust-analyzer.serverPath": {
                     "type": [
                         "null",
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index bf915102c..b72206d3c 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -1,6 +1,6 @@
 import * as os from "os";
 import * as vscode from 'vscode';
-import { BinarySource } from "./installation/interfaces";
+import { ArtifactSource } from "./installation/interfaces";
 import { log } from "./util";
 
 const RA_LSP_DEBUG = process.env.__RA_LSP_SERVER_DEBUG;
@@ -114,12 +114,12 @@ export class Config {
         }
     }
 
-    get serverSource(): null | BinarySource {
+    get serverSource(): null | ArtifactSource {
         const serverPath = RA_LSP_DEBUG ?? this.cfg.get<null | string>("serverPath");
 
         if (serverPath) {
             return {
-                type: BinarySource.Type.ExplicitPath,
+                type: ArtifactSource.Type.ExplicitPath,
                 path: Config.replaceTildeWithHomeDir(serverPath)
             };
         }
@@ -129,11 +129,12 @@ export class Config {
         if (!prebuiltBinaryName) return null;
 
         return {
-            type: BinarySource.Type.GithubRelease,
+            type: ArtifactSource.Type.GithubRelease,
             dir: this.ctx.globalStoragePath,
             file: prebuiltBinaryName,
             storage: this.ctx.globalState,
-            version: Config.extensionVersion,
+            tag: Config.extensionVersion,
+            askBeforeDownload: this.cfg.get("updates.askBeforeDownload") as boolean,
             repo: {
                 name: "rust-analyzer",
                 owner: "rust-analyzer",
diff --git a/editors/code/src/installation/interfaces.ts b/editors/code/src/installation/interfaces.ts
index e40839e4b..50b635921 100644
--- a/editors/code/src/installation/interfaces.ts
+++ b/editors/code/src/installation/interfaces.ts
@@ -14,14 +14,14 @@ export interface ArtifactReleaseInfo {
 }
 
 /**
- * Represents the source of a binary artifact which is either specified by the user
+ * Represents the source of a an artifact which is either specified by the user
  * explicitly, or bundled by this extension from GitHub releases.
  */
-export type BinarySource = BinarySource.ExplicitPath | BinarySource.GithubRelease;
+export type ArtifactSource = ArtifactSource.ExplicitPath | ArtifactSource.GithubRelease;
 
-export namespace BinarySource {
+export namespace ArtifactSource {
     /**
-     * Type tag for `BinarySource` discriminated union.
+     * Type tag for `ArtifactSource` discriminated union.
      */
     export const enum Type { ExplicitPath, GithubRelease }
 
@@ -56,13 +56,18 @@ export namespace BinarySource {
         /**
          * Tag of github release that denotes a version required by this extension.
          */
-        version: string;
+        tag: string;
 
         /**
          * Object that provides `get()/update()` operations to store metadata
          * about the actual binary, e.g. its actual version.
          */
         storage: vscode.Memento;
+
+        /**
+         * Ask for the user permission before downloading the artifact.
+         */
+        askBeforeDownload: boolean;
     }
 
 }
diff --git a/editors/code/src/installation/server.ts b/editors/code/src/installation/server.ts
index 6a6cf4f8c..ef1c45ff6 100644
--- a/editors/code/src/installation/server.ts
+++ b/editors/code/src/installation/server.ts
@@ -3,12 +3,12 @@ import * as path from "path";
 import { promises as dns } from "dns";
 import { spawnSync } from "child_process";
 
-import { BinarySource } from "./interfaces";
+import { ArtifactSource } from "./interfaces";
 import { fetchArtifactReleaseInfo } from "./fetch_artifact_release_info";
 import { downloadArtifact } from "./download_artifact";
 import { log, assert } from "../util";
 
-export async function ensureServerBinary(source: null | BinarySource): Promise<null | string> {
+export async function ensureServerBinary(source: null | ArtifactSource): Promise<null | string> {
     if (!source) {
         vscode.window.showErrorMessage(
             "Unfortunately we don't ship binaries for your platform yet. " +
@@ -22,7 +22,7 @@ export async function ensureServerBinary(source: null | BinarySource): Promise<n
     }
 
     switch (source.type) {
-        case BinarySource.Type.ExplicitPath: {
+        case ArtifactSource.Type.ExplicitPath: {
             if (isBinaryAvailable(source.path)) {
                 return source.path;
             }
@@ -34,11 +34,11 @@ export async function ensureServerBinary(source: null | BinarySource): Promise<n
             );
             return null;
         }
-        case BinarySource.Type.GithubRelease: {
+        case ArtifactSource.Type.GithubRelease: {
             const prebuiltBinaryPath = path.join(source.dir, source.file);
 
             const installedVersion: null | string = getServerVersion(source.storage);
-            const requiredVersion: string = source.version;
+            const requiredVersion: string = source.tag;
 
             log.debug("Installed version:", installedVersion, "required:", requiredVersion);
 
@@ -46,12 +46,14 @@ export async function ensureServerBinary(source: null | BinarySource): Promise<n
                 return prebuiltBinaryPath;
             }
 
-            const userResponse = await vscode.window.showInformationMessage(
-                `Language server version ${source.version} for rust-analyzer is not installed. ` +
-                "Do you want to download it now?",
-                "Download now", "Cancel"
-            );
-            if (userResponse !== "Download now") return null;
+            if (source.askBeforeDownload) {
+                const userResponse = await vscode.window.showInformationMessage(
+                    `Language server version ${source.tag} for rust-analyzer is not installed. ` +
+                    "Do you want to download it now?",
+                    "Download now", "Cancel"
+                );
+                if (userResponse !== "Download now") return null;
+            }
 
             if (!await downloadServer(source)) return null;
 
@@ -60,9 +62,9 @@ export async function ensureServerBinary(source: null | BinarySource): Promise<n
     }
 }
 
-async function downloadServer(source: BinarySource.GithubRelease): Promise<boolean> {
+async function downloadServer(source: ArtifactSource.GithubRelease): Promise<boolean> {
     try {
-        const releaseInfo = await fetchArtifactReleaseInfo(source.repo, source.file, source.version);
+        const releaseInfo = await fetchArtifactReleaseInfo(source.repo, source.file, source.tag);
 
         await downloadArtifact(releaseInfo, source.file, source.dir, "language server");
         await setServerVersion(source.storage, releaseInfo.releaseName);