26 files changed, 704 insertions, 393 deletions

diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 0434b6128..21ac3a4bc 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -11,6 +11,7 @@ jobs:
   dist:
     name: dist
     runs-on: ${{ matrix.os }}
+    if: github.repository == "rust-analyzer/rust-analyzer"
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
diff --git a/Cargo.lock b/Cargo.lock
index efe8dd189..f6df77206 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -419,9 +419,9 @@ dependencies = [
 
 [[package]]
 name = "globset"
-version = "0.4.4"
+version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "925aa2cac82d8834e2b2a4415b6f6879757fb5c0928fc445ae76461a12eed8f2"
+checksum = "7ad1da430bd7281dde2576f44c84cc3f0f7b475e7202cd503042dff01a8c8120"
 dependencies = [
  "aho-corasick",
  "bstr",
@@ -668,11 +668,11 @@ checksum = "3728d817d99e5ac407411fa471ff9800a778d88a24685968b36824eaf4bee400"
 
 [[package]]
 name = "memoffset"
-version = "0.5.3"
+version = "0.5.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "75189eb85871ea5c2e2c15abbdd541185f63b408415e5051f5cac122d8c774b9"
+checksum = "b4fc2c02a7e374099d4ee95a193111f72d2110197fe200272371758f6c3643d8"
 dependencies = [
- "rustc_version",
+ "autocfg",
 ]
 
 [[package]]
@@ -1133,9 +1133,9 @@ dependencies = [
 
 [[package]]
 name = "ra_vfs"
-version = "0.5.2"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bc898f237e4b4498959ae0100c688793a23e77624d44ef710ba70094217f98e0"
+checksum = "58a265769d5e5655345a9fcbd870a1a7c3658558c0d8efaed79e0669358f46b8"
 dependencies = [
  "crossbeam-channel",
  "jod-thread",
@@ -1332,15 +1332,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "rustc_version"
-version = "0.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
-dependencies = [
- "semver",
-]
-
-[[package]]
 name = "ryu"
 version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index c3e1c68b7..d171d2dfd 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -2,7 +2,7 @@
 
 use std::sync::Arc;
 
-use mbe::MacroRules;
+use mbe::{ExpandResult, MacroRules};
 use ra_db::{salsa, SourceDatabase};
 use ra_parser::FragmentKind;
 use ra_prof::profile;
@@ -27,11 +27,12 @@ impl TokenExpander {
         db: &dyn AstDatabase,
         id: LazyMacroId,
         tt: &tt::Subtree,
-    ) -> Result<tt::Subtree, mbe::ExpandError> {
+    ) -> mbe::ExpandResult<tt::Subtree> {
         match self {
             TokenExpander::MacroRules(it) => it.expand(tt),
-            TokenExpander::Builtin(it) => it.expand(db, id, tt),
-            TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt),
+            // FIXME switch these to ExpandResult as well
+            TokenExpander::Builtin(it) => it.expand(db, id, tt).into(),
+            TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt).into(),
         }
     }
 
@@ -66,7 +67,7 @@ pub trait AstDatabase: SourceDatabase {
     fn macro_def(&self, id: MacroDefId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>>;
     fn parse_macro(&self, macro_file: MacroFile)
         -> Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>;
-    fn macro_expand(&self, macro_call: MacroCallId) -> Result<Arc<tt::Subtree>, String>;
+    fn macro_expand(&self, macro_call: MacroCallId) -> (Option<Arc<tt::Subtree>>, Option<String>);
 
     #[salsa::interned]
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
@@ -153,7 +154,7 @@ pub(crate) fn macro_arg(
 pub(crate) fn macro_expand(
     db: &dyn AstDatabase,
     id: MacroCallId,
-) -> Result<Arc<tt::Subtree>, String> {
+) -> (Option<Arc<tt::Subtree>>, Option<String>) {
     macro_expand_with_arg(db, id, None)
 }
 
@@ -174,31 +175,38 @@ fn macro_expand_with_arg(
     db: &dyn AstDatabase,
     id: MacroCallId,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
-) -> Result<Arc<tt::Subtree>, String> {
+) -> (Option<Arc<tt::Subtree>>, Option<String>) {
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
         MacroCallId::EagerMacro(id) => {
             if arg.is_some() {
-                return Err(
-                    "hypothetical macro expansion not implemented for eager macro".to_owned()
+                return (
+                    None,
+                    Some("hypothetical macro expansion not implemented for eager macro".to_owned()),
                 );
             } else {
-                return Ok(db.lookup_intern_eager_expansion(id).subtree);
+                return (Some(db.lookup_intern_eager_expansion(id).subtree), None);
             }
         }
     };
 
     let loc = db.lookup_intern_macro(lazy_id);
-    let macro_arg = arg.or_else(|| db.macro_arg(id)).ok_or("Fail to args in to tt::TokenTree")?;
+    let macro_arg = match arg.or_else(|| db.macro_arg(id)) {
+        Some(it) => it,
+        None => return (None, Some("Fail to args in to tt::TokenTree".into())),
+    };
 
-    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))?;
+    let macro_rules = match db.macro_def(loc.def) {
+        Some(it) => it,
+        None => return (None, Some("Fail to find macro definition".into())),
+    };
+    let ExpandResult(tt, err) = macro_rules.0.expand(db, lazy_id, &macro_arg.0);
     // Set a hard limit for the expanded tt
     let count = tt.count();
     if count > 65536 {
-        return Err(format!("Total tokens count exceed limit : count = {}", count));
+        return (None, Some(format!("Total tokens count exceed limit : count = {}", count)));
     }
-    Ok(Arc::new(tt))
+    (Some(Arc::new(tt)), err.map(|e| format!("{:?}", e)))
 }
 
 pub(crate) fn parse_or_expand(db: &dyn AstDatabase, file_id: HirFileId) -> Option<SyntaxNode> {
@@ -225,42 +233,41 @@ pub fn parse_macro_with_arg(
     let _p = profile("parse_macro_query");
 
     let macro_call_id = macro_file.macro_call_id;
-    let expansion = if let Some(arg) = arg {
+    let (tt, err) = 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,
-            // such that the following log will not call anyway.
-            match macro_call_id {
-                MacroCallId::LazyMacro(id) => {
-                    let loc: MacroCallLoc = db.lookup_intern_macro(id);
-                    let node = loc.kind.node(db);
-
-                    // collect parent information for warning log
-                    let parents = std::iter::successors(loc.kind.file_id().call_node(db), |it| {
-                        it.file_id.call_node(db)
-                    })
-                    .map(|n| format!("{:#}", n.value))
-                    .collect::<Vec<_>>()
-                    .join("\n");
-
-                    log::warn!(
-                        "fail on macro_parse: (reason: {} macro_call: {:#}) parents: {}",
-                        err,
-                        node.value,
-                        parents
-                    );
-                }
-                _ => {
-                    log::warn!("fail on macro_parse: (reason: {})", err);
-                }
+    if let Some(err) = err {
+        // Note:
+        // The final goal we would like to make all parse_macro success,
+        // such that the following log will not call anyway.
+        match macro_call_id {
+            MacroCallId::LazyMacro(id) => {
+                let loc: MacroCallLoc = db.lookup_intern_macro(id);
+                let node = loc.kind.node(db);
+
+                // collect parent information for warning log
+                let parents = std::iter::successors(loc.kind.file_id().call_node(db), |it| {
+                    it.file_id.call_node(db)
+                })
+                .map(|n| format!("{:#}", n.value))
+                .collect::<Vec<_>>()
+                .join("\n");
+
+                log::warn!(
+                    "fail on macro_parse: (reason: {} macro_call: {:#}) parents: {}",
+                    err,
+                    node.value,
+                    parents
+                );
+            }
+            _ => {
+                log::warn!("fail on macro_parse: (reason: {})", err);
             }
-        })
-        .ok()?;
+        }
+    };
+    let tt = tt?;
 
     let fragment_kind = to_fragment_kind(db, macro_call_id);
 
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index 3b7022ad5..2e309a379 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -462,7 +462,7 @@ fn main() {
 fn infer_builtin_macros_include() {
     let (db, pos) = TestDB::with_position(
         r#"
-//- /main.rs 
+//- /main.rs
 #[rustc_builtin_macro]
 macro_rules! include {() => {}}
 
@@ -483,7 +483,7 @@ fn bar() -> u32 {0}
 fn infer_builtin_macros_include_concat() {
     let (db, pos) = TestDB::with_position(
         r#"
-//- /main.rs 
+//- /main.rs
 #[rustc_builtin_macro]
 macro_rules! include {() => {}}
 
@@ -507,7 +507,7 @@ fn bar() -> u32 {0}
 fn infer_builtin_macros_include_concat_with_bad_env_should_failed() {
     let (db, pos) = TestDB::with_position(
         r#"
-//- /main.rs 
+//- /main.rs
 #[rustc_builtin_macro]
 macro_rules! include {() => {}}
 
@@ -534,7 +534,7 @@ fn bar() -> u32 {0}
 fn infer_builtin_macros_include_itself_should_failed() {
     let (db, pos) = TestDB::with_position(
         r#"
-//- /main.rs 
+//- /main.rs
 #[rustc_builtin_macro]
 macro_rules! include {() => {}}
 
diff --git a/crates/ra_ide/src/completion/complete_dot.rs b/crates/ra_ide/src/completion/complete_dot.rs
index f07611d88..82ec16913 100644
--- a/crates/ra_ide/src/completion/complete_dot.rs
+++ b/crates/ra_ide/src/completion/complete_dot.rs
@@ -720,7 +720,18 @@ mod tests {
                 }
                 ",
             ),
-            @r###"[]"###
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [156; 156),
+                delete: [156; 156),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
         );
     }
 
@@ -752,6 +763,43 @@ mod tests {
     }
 
     #[test]
+    fn macro_expansion_resilient() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! dbg {
+                    () => {};
+                    ($val:expr) => {
+                        match $val { tmp => { tmp } }
+                    };
+                    // Trailing comma with single argument is ignored
+                    ($val:expr,) => { $crate::dbg!($val) };
+                    ($($val:expr),+ $(,)?) => {
+                        ($($crate::dbg!($val)),+,)
+                    };
+                }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    dbg!(a.<|>)
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [552; 552),
+                delete: [552; 552),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
     fn test_method_completion_3547() {
         assert_debug_snapshot!(
             do_ref_completion(
diff --git a/crates/ra_ide/src/completion/complete_pattern.rs b/crates/ra_ide/src/completion/complete_pattern.rs
index 6a1a66ef1..cb84bb934 100644
--- a/crates/ra_ide/src/completion/complete_pattern.rs
+++ b/crates/ra_ide/src/completion/complete_pattern.rs
@@ -89,7 +89,6 @@ 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 } }
@@ -102,6 +101,16 @@ mod tests {
             }
             ",
         );
-        assert_debug_snapshot!(completions, @r###"[]"###);
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "E",
+                source_range: [151; 151),
+                delete: [151; 151),
+                insert: "E",
+                kind: Enum,
+            },
+        ]
+        "###);
     }
 }
diff --git a/crates/ra_ide/src/completion/complete_scope.rs b/crates/ra_ide/src/completion/complete_scope.rs
index 5ffff5a1c..81d3cc1b6 100644
--- a/crates/ra_ide/src/completion/complete_scope.rs
+++ b/crates/ra_ide/src/completion/complete_scope.rs
@@ -811,7 +811,44 @@ mod tests {
                 }
                 "
             ),
-            @"[]"
+            @r###"
+        [
+            CompletionItem {
+                label: "m!",
+                source_range: [145; 145),
+                delete: [145; 145),
+                insert: "m!($0)",
+                kind: Macro,
+                detail: "macro_rules! m",
+            },
+            CompletionItem {
+                label: "quux(…)",
+                source_range: [145; 145),
+                delete: [145; 145),
+                insert: "quux(${1:x})$0",
+                kind: Function,
+                lookup: "quux",
+                detail: "fn quux(x: i32)",
+                trigger_call_info: true,
+            },
+            CompletionItem {
+                label: "x",
+                source_range: [145; 145),
+                delete: [145; 145),
+                insert: "x",
+                kind: Binding,
+                detail: "i32",
+            },
+            CompletionItem {
+                label: "y",
+                source_range: [145; 145),
+                delete: [145; 145),
+                insert: "y",
+                kind: Binding,
+                detail: "i32",
+            },
+        ]
+        "###
         );
     }
 
@@ -869,6 +906,59 @@ mod tests {
     }
 
     #[test]
+    fn completes_in_simple_macro_without_closing_parens() {
+        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)",
+                trigger_call_info: true,
+            },
+            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",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
     fn completes_unresolved_uses() {
         assert_debug_snapshot!(
             do_reference_completion(
diff --git a/crates/ra_ide/src/completion/completion_context.rs b/crates/ra_ide/src/completion/completion_context.rs
index 3646fb8dc..54589a2a8 100644
--- a/crates/ra_ide/src/completion/completion_context.rs
+++ b/crates/ra_ide/src/completion/completion_context.rs
@@ -135,7 +135,7 @@ impl<'a> CompletionContext<'a> {
                 ),
             ) {
                 let new_offset = hypothetical_expansion.1.text_range().start();
-                if new_offset >= actual_expansion.text_range().end() {
+                if new_offset > actual_expansion.text_range().end() {
                     break;
                 }
                 original_file = actual_expansion;
diff --git a/crates/ra_ide/src/expand_macro.rs b/crates/ra_ide/src/expand_macro.rs
index f6667cb33..e58526f31 100644
--- a/crates/ra_ide/src/expand_macro.rs
+++ b/crates/ra_ide/src/expand_macro.rs
@@ -259,7 +259,7 @@ fn some_thing() -> u32 {
         );
 
         assert_eq!(res.name, "foo");
-        assert_snapshot!(res.expansion, @r###"bar!()"###);
+        assert_snapshot!(res.expansion, @r###""###);
     }
 
     #[test]
diff --git a/crates/ra_mbe/src/lib.rs b/crates/ra_mbe/src/lib.rs
index 43afe24cc..6a9037bfc 100644
--- a/crates/ra_mbe/src/lib.rs
+++ b/crates/ra_mbe/src/lib.rs
@@ -150,7 +150,7 @@ impl MacroRules {
         Ok(MacroRules { rules, shift: Shift::new(tt) })
     }
 
-    pub fn expand(&self, tt: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {
+    pub fn expand(&self, tt: &tt::Subtree) -> ExpandResult<tt::Subtree> {
         // apply shift
         let mut tt = tt.clone();
         self.shift.shift_all(&mut tt);
@@ -209,5 +209,35 @@ fn validate(pattern: &tt::Subtree) -> Result<(), ParseError> {
     Ok(())
 }
 
+pub struct ExpandResult<T>(pub T, pub Option<ExpandError>);
+
+impl<T> ExpandResult<T> {
+    pub fn ok(t: T) -> ExpandResult<T> {
+        ExpandResult(t, None)
+    }
+
+    pub fn only_err(err: ExpandError) -> ExpandResult<T>
+    where
+        T: Default,
+    {
+        ExpandResult(Default::default(), Some(err))
+    }
+
+    pub fn map<U>(self, f: impl FnOnce(T) -> U) -> ExpandResult<U> {
+        ExpandResult(f(self.0), self.1)
+    }
+
+    pub fn result(self) -> Result<T, ExpandError> {
+        self.1.map(Err).unwrap_or(Ok(self.0))
+    }
+}
+
+impl<T: Default> From<Result<T, ExpandError>> for ExpandResult<T> {
+    fn from(result: Result<T, ExpandError>) -> ExpandResult<T> {
+        result
+            .map_or_else(|e| ExpandResult(Default::default(), Some(e)), |it| ExpandResult(it, None))
+    }
+}
+
 #[cfg(test)]
 mod tests;
diff --git a/crates/ra_mbe/src/mbe_expander.rs b/crates/ra_mbe/src/mbe_expander.rs
index b455b7321..b1eacf124 100644
--- a/crates/ra_mbe/src/mbe_expander.rs
+++ b/crates/ra_mbe/src/mbe_expander.rs
@@ -8,19 +8,51 @@ mod transcriber;
 use ra_syntax::SmolStr;
 use rustc_hash::FxHashMap;
 
-use crate::ExpandError;
+use crate::{ExpandError, ExpandResult};
 
-pub(crate) fn expand(
-    rules: &crate::MacroRules,
-    input: &tt::Subtree,
-) -> Result<tt::Subtree, ExpandError> {
-    rules.rules.iter().find_map(|it| expand_rule(it, input).ok()).ok_or(ExpandError::NoMatchingRule)
+pub(crate) fn expand(rules: &crate::MacroRules, input: &tt::Subtree) -> ExpandResult<tt::Subtree> {
+    expand_rules(&rules.rules, input)
 }
 
-fn expand_rule(rule: &crate::Rule, input: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {
-    let bindings = matcher::match_(&rule.lhs, input)?;
-    let res = transcriber::transcribe(&rule.rhs, &bindings)?;
-    Ok(res)
+fn expand_rules(rules: &[crate::Rule], input: &tt::Subtree) -> ExpandResult<tt::Subtree> {
+    let mut match_: Option<(matcher::Match, &crate::Rule)> = None;
+    for rule in rules {
+        let new_match = match matcher::match_(&rule.lhs, input) {
+            Ok(m) => m,
+            Err(_e) => {
+                // error in pattern parsing
+                continue;
+            }
+        };
+        if new_match.err.is_none() {
+            // If we find a rule that applies without errors, we're done.
+            // Unconditionally returning the transcription here makes the
+            // `test_repeat_bad_var` test fail.
+            let ExpandResult(res, transcribe_err) =
+                transcriber::transcribe(&rule.rhs, &new_match.bindings);
+            if transcribe_err.is_none() {
+                return ExpandResult::ok(res);
+            }
+        }
+        // Use the rule if we matched more tokens, or had fewer errors
+        if let Some((prev_match, _)) = &match_ {
+            if (new_match.unmatched_tts, new_match.err_count)
+                < (prev_match.unmatched_tts, prev_match.err_count)
+            {
+                match_ = Some((new_match, rule));
+            }
+        } else {
+            match_ = Some((new_match, rule));
+        }
+    }
+    if let Some((match_, rule)) = match_ {
+        // if we got here, there was no match without errors
+        let ExpandResult(result, transcribe_err) =
+            transcriber::transcribe(&rule.rhs, &match_.bindings);
+        ExpandResult(result, match_.err.or(transcribe_err))
+    } else {
+        ExpandResult(tt::Subtree::default(), Some(ExpandError::NoMatchingRule))
+    }
 }
 
 /// The actual algorithm for expansion is not too hard, but is pretty tricky.
@@ -111,7 +143,7 @@ mod tests {
     }
 
     fn assert_err(macro_body: &str, invocation: &str, err: ExpandError) {
-        assert_eq!(expand_first(&create_rules(&format_macro(macro_body)), invocation), Err(err));
+        assert_eq!(expand_first(&create_rules(&format_macro(macro_body)), invocation).1, Some(err));
     }
 
     fn format_macro(macro_body: &str) -> String {
@@ -135,10 +167,7 @@ mod tests {
         crate::MacroRules::parse(&definition_tt).unwrap()
     }
 
-    fn expand_first(
-        rules: &crate::MacroRules,
-        invocation: &str,
-    ) -> Result<tt::Subtree, ExpandError> {
+    fn expand_first(rules: &crate::MacroRules, invocation: &str) -> ExpandResult<tt::Subtree> {
         let source_file = ast::SourceFile::parse(invocation).ok().unwrap();
         let macro_invocation =
             source_file.syntax().descendants().find_map(ast::MacroCall::cast).unwrap();
@@ -146,6 +175,6 @@ mod tests {
         let (invocation_tt, _) =
             ast_to_token_tree(&macro_invocation.token_tree().unwrap()).unwrap();
 
-        expand_rule(&rules.rules[0], &invocation_tt)
+        expand_rules(&rules.rules, &invocation_tt)
     }
 }
diff --git a/crates/ra_mbe/src/mbe_expander/matcher.rs b/crates/ra_mbe/src/mbe_expander/matcher.rs
index 49c53183a..2579382da 100644
--- a/crates/ra_mbe/src/mbe_expander/matcher.rs
+++ b/crates/ra_mbe/src/mbe_expander/matcher.rs
@@ -8,6 +8,7 @@ use crate::{
     ExpandError,
 };
 
+use super::ExpandResult;
 use ra_parser::{FragmentKind::*, TreeSink};
 use ra_syntax::{SmolStr, SyntaxKind};
 use tt::buffer::{Cursor, TokenBuffer};
@@ -58,36 +59,61 @@ macro_rules! err {
     };
 }
 
-macro_rules! bail {
-    ($($tt:tt)*) => {
-        return Err(err!($($tt)*))
-    };
+#[derive(Debug, Default)]
+pub(super) struct Match {
+    pub bindings: Bindings,
+    /// We currently just keep the first error and count the rest to compare matches.
+    pub err: Option<ExpandError>,
+    pub err_count: usize,
+    /// How many top-level token trees were left to match.
+    pub unmatched_tts: usize,
 }
 
-pub(super) fn match_(pattern: &tt::Subtree, src: &tt::Subtree) -> Result<Bindings, ExpandError> {
+impl Match {
+    pub fn add_err(&mut self, err: ExpandError) {
+        let prev_err = self.err.take();
+        self.err = prev_err.or(Some(err));
+        self.err_count += 1;
+    }
+}
+
+// General note: These functions have two channels to return errors, a `Result`
+// return value and the `&mut Match`. The returned Result is for pattern parsing
+// errors; if a branch of the macro definition doesn't parse, it doesn't make
+// sense to try using it. Matching errors are added to the `Match`. It might
+// make sense to make pattern parsing a separate step?
+
+pub(super) fn match_(pattern: &tt::Subtree, src: &tt::Subtree) -> Result<Match, ExpandError> {
     assert!(pattern.delimiter == None);
 
-    let mut res = Bindings::default();
+    let mut res = Match::default();
     let mut src = TtIter::new(src);
 
     match_subtree(&mut res, pattern, &mut src)?;
 
     if src.len() > 0 {
-        bail!("leftover tokens");
+        res.unmatched_tts += src.len();
+        res.add_err(err!("leftover tokens"));
     }
 
     Ok(res)
 }
 
 fn match_subtree(
-    bindings: &mut Bindings,
+    res: &mut Match,
     pattern: &tt::Subtree,
     src: &mut TtIter,
 ) -> Result<(), ExpandError> {
     for op in parse_pattern(pattern) {
         match op? {
             Op::TokenTree(tt::TokenTree::Leaf(lhs)) => {
-                let rhs = src.expect_leaf().map_err(|()| err!("expected leaf: `{}`", lhs))?;
+                let rhs = match src.expect_leaf() {
+                    Ok(l) => l,
+                    Err(()) => {
+                        res.add_err(err!("expected leaf: `{}`", lhs));
+                        continue;
+                    }
+                };
                 match (lhs, rhs) {
                     (
                         tt::Leaf::Punct(tt::Punct { char: lhs, .. }),
@@ -101,31 +127,51 @@ fn match_subtree(
                         tt::Leaf::Literal(tt::Literal { text: lhs, .. }),
                         tt::Leaf::Literal(tt::Literal { text: rhs, .. }),
                     ) if lhs == rhs => (),
-                    _ => return Err(ExpandError::UnexpectedToken),
+                    _ => {
+                        res.add_err(ExpandError::UnexpectedToken);
+                    }
                 }
             }
             Op::TokenTree(tt::TokenTree::Subtree(lhs)) => {
-                let rhs = src.expect_subtree().map_err(|()| err!("expected subtree"))?;
+                let rhs = match src.expect_subtree() {
+                    Ok(s) => s,
+                    Err(()) => {
+                        res.add_err(err!("expected subtree"));
+                        continue;
+                    }
+                };
                 if lhs.delimiter_kind() != rhs.delimiter_kind() {
-                    bail!("mismatched delimiter")
+                    res.add_err(err!("mismatched delimiter"));
+                    continue;
                 }
                 let mut src = TtIter::new(rhs);
-                match_subtree(bindings, lhs, &mut src)?;
+                match_subtree(res, lhs, &mut src)?;
                 if src.len() > 0 {
-                    bail!("leftover tokens");
+                    res.add_err(err!("leftover tokens"));
                 }
             }
             Op::Var { name, kind } => {
-                let kind = kind.as_ref().ok_or(ExpandError::UnexpectedToken)?;
-                match match_meta_var(kind.as_str(), src)? {
+                let kind = match kind {
+                    Some(k) => k,
+                    None => {
+                        res.add_err(ExpandError::UnexpectedToken);
+                        continue;
+                    }
+                };
+                let ExpandResult(matched, match_err) = match_meta_var(kind.as_str(), src);
+                match matched {
                     Some(fragment) => {
-                        bindings.inner.insert(name.clone(), Binding::Fragment(fragment));
+                        res.bindings.inner.insert(name.clone(), Binding::Fragment(fragment));
                     }
-                    None => bindings.push_optional(name),
+                    None if match_err.is_none() => res.bindings.push_optional(name),
+                    _ => {}
+                }
+                if let Some(err) = match_err {
+                    res.add_err(err);
                 }
             }
             Op::Repeat { subtree, kind, separator } => {
-                match_repeat(bindings, subtree, kind, separator, src)?
+                match_repeat(res, subtree, kind, separator, src)?;
             }
         }
     }
@@ -221,7 +267,7 @@ impl<'a> TtIter<'a> {
     pub(crate) fn expect_fragment(
         &mut self,
         fragment_kind: ra_parser::FragmentKind,
-    ) -> Result<tt::TokenTree, ()> {
+    ) -> ExpandResult<Option<tt::TokenTree>> {
         pub(crate) struct OffsetTokenSink<'a> {
             pub(crate) cursor: Cursor<'a>,
             pub(crate) error: bool,
@@ -246,45 +292,51 @@ impl<'a> TtIter<'a> {
 
         ra_parser::parse_fragment(&mut src, &mut sink, fragment_kind);
 
+        let mut err = None;
         if !sink.cursor.is_root() || sink.error {
-            // FIXME better recovery in this case would help completion inside macros immensely
-            return Err(());
+            err = Some(err!("expected {:?}", fragment_kind));
         }
 
         let mut curr = buffer.begin();
         let mut res = vec![];
 
-        while curr != sink.cursor {
-            if let Some(token) = curr.token_tree() {
-                res.push(token);
+        if sink.cursor.is_root() {
+            while curr != sink.cursor {
+                if let Some(token) = curr.token_tree() {
+                    res.push(token);
+                }
+                curr = curr.bump();
             }
-            curr = curr.bump();
         }
         self.inner = self.inner.as_slice()[res.len()..].iter();
-        match res.len() {
-            0 => Err(()),
-            1 => Ok(res[0].clone()),
-            _ => Ok(tt::TokenTree::Subtree(tt::Subtree {
+        if res.len() == 0 && err.is_none() {
+            err = Some(err!("no tokens consumed"));
+        }
+        let res = match res.len() {
+            1 => Some(res[0].clone()),
+            0 => None,
+            _ => Some(tt::TokenTree::Subtree(tt::Subtree {
                 delimiter: None,
                 token_trees: res.into_iter().cloned().collect(),
             })),
-        }
+        };
+        ExpandResult(res, err)
     }
 
     pub(crate) fn eat_vis(&mut self) -> Option<tt::TokenTree> {
         let mut fork = self.clone();
         match fork.expect_fragment(Visibility) {
-            Ok(tt) => {
+            ExpandResult(tt, None) => {
                 *self = fork;
-                Some(tt)
+                tt
             }
-            Err(()) => None,
+            ExpandResult(_, Some(_)) => None,
         }
     }
 }
 
 pub(super) fn match_repeat(
-    bindings: &mut Bindings,
+    res: &mut Match,
     pattern: &tt::Subtree,
     kind: RepeatKind,
     separator: Option<Separator>,
@@ -304,36 +356,46 @@ pub(super) fn match_repeat(
             }
         }
 
-        let mut nested = Bindings::default();
-        match match_subtree(&mut nested, pattern, &mut fork) {
-            Ok(()) => {
-                limit -= 1;
-                if limit == 0 {
-                    log::warn!("match_lhs excced in repeat pattern exceed limit => {:#?}\n{:#?}\n{:#?}\n{:#?}", pattern, src, kind, separator);
-                    break;
-                }
-                *src = fork;
+        let mut nested = Match::default();
+        match_subtree(&mut nested, pattern, &mut fork)?;
+        if nested.err.is_none() {
+            limit -= 1;
+            if limit == 0 {
+                log::warn!(
+                    "match_lhs exceeded repeat pattern limit => {:#?}\n{:#?}\n{:#?}\n{:#?}",
+                    pattern,
+                    src,
+                    kind,
+                    separator
+                );
+                break;
+            }
+            *src = fork;
 
-                bindings.push_nested(counter, nested)?;
-                counter += 1;
-                if counter == 1 {
-                    if let RepeatKind::ZeroOrOne = kind {
-                        break;
-                    }
+            if let Err(err) = res.bindings.push_nested(counter, nested.bindings) {
+                res.add_err(err);
+            }
+            counter += 1;
+            if counter == 1 {
+                if let RepeatKind::ZeroOrOne = kind {
+                    break;
                 }
             }
-            Err(_) => break,
+        } else {
+            break;
         }
     }
 
     match (kind, counter) {
-        (RepeatKind::OneOrMore, 0) => return Err(ExpandError::UnexpectedToken),
+        (RepeatKind::OneOrMore, 0) => {
+            res.add_err(ExpandError::UnexpectedToken);
+        }
         (_, 0) => {
             // Collect all empty variables in subtrees
             let mut vars = Vec::new();
             collect_vars(&mut vars, pattern)?;
             for var in vars {
-                bindings.push_empty(&var)
+                res.bindings.push_empty(&var)
             }
         }
         _ => (),
@@ -341,7 +403,7 @@ pub(super) fn match_repeat(
     Ok(())
 }
 
-fn match_meta_var(kind: &str, input: &mut TtIter) -> Result<Option<Fragment>, ExpandError> {
+fn match_meta_var(kind: &str, input: &mut TtIter) -> ExpandResult<Option<Fragment>> {
     let fragment = match kind {
         "path" => Path,
         "expr" => Expr,
@@ -352,34 +414,32 @@ fn match_meta_var(kind: &str, input: &mut TtIter) -> Result<Option<Fragment>, Ex
         "meta" => MetaItem,
         "item" => Item,
         _ => {
-            let tt = match kind {
-                "ident" => {
-                    let ident = input.expect_ident().map_err(|()| err!("expected ident"))?.clone();
-                    tt::Leaf::from(ident).into()
-                }
-                "tt" => input.expect_tt().map_err(|()| err!())?.clone(),
-                "lifetime" => {
-                    let ident = input.expect_lifetime().map_err(|()| err!())?;
-                    tt::Leaf::Ident(ident.clone()).into()
-                }
-                "literal" => {
-                    let literal = input.expect_literal().map_err(|()| err!())?.clone();
-                    tt::Leaf::from(literal).into()
-                }
+            let tt_result = match kind {
+                "ident" => input
+                    .expect_ident()
+                    .map(|ident| Some(tt::Leaf::from(ident.clone()).into()))
+                    .map_err(|()| err!("expected ident")),
+                "tt" => input.expect_tt().map(Some).map_err(|()| err!()),
+                "lifetime" => input
+                    .expect_lifetime()
+                    .map(|ident| Some(tt::Leaf::Ident(ident.clone()).into()))
+                    .map_err(|()| err!("expected lifetime")),
+                "literal" => input
+                    .expect_literal()
+                    .map(|literal| Some(tt::Leaf::from(literal.clone()).into()))
+                    .map_err(|()| err!()),
                 // `vis` is optional
                 "vis" => match input.eat_vis() {
-                    Some(vis) => vis,
-                    None => return Ok(None),
+                    Some(vis) => Ok(Some(vis)),
+                    None => Ok(None),
                 },
-                _ => return Err(ExpandError::UnexpectedToken),
+                _ => Err(ExpandError::UnexpectedToken),
             };
-            return Ok(Some(Fragment::Tokens(tt)));
+            return tt_result.map(|it| it.map(Fragment::Tokens)).into();
         }
     };
-    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))
+    let result = input.expect_fragment(fragment);
+    result.map(|tt| if kind == "expr" { tt.map(Fragment::Ast) } else { tt.map(Fragment::Tokens) })
 }
 
 fn collect_vars(buf: &mut Vec<SmolStr>, pattern: &tt::Subtree) -> Result<(), ExpandError> {
diff --git a/crates/ra_mbe/src/mbe_expander/transcriber.rs b/crates/ra_mbe/src/mbe_expander/transcriber.rs
index 7662020f3..4b173edd3 100644
--- a/crates/ra_mbe/src/mbe_expander/transcriber.rs
+++ b/crates/ra_mbe/src/mbe_expander/transcriber.rs
@@ -3,6 +3,7 @@
 
 use ra_syntax::SmolStr;
 
+use super::ExpandResult;
 use crate::{
     mbe_expander::{Binding, Bindings, Fragment},
     parser::{parse_template, Op, RepeatKind, Separator},
@@ -49,10 +50,7 @@ impl Bindings {
     }
 }
 
-pub(super) fn transcribe(
-    template: &tt::Subtree,
-    bindings: &Bindings,
-) -> Result<tt::Subtree, ExpandError> {
+pub(super) fn transcribe(template: &tt::Subtree, bindings: &Bindings) -> ExpandResult<tt::Subtree> {
     assert!(template.delimiter == None);
     let mut ctx = ExpandCtx { bindings: &bindings, nesting: Vec::new() };
     expand_subtree(&mut ctx, template)
@@ -75,35 +73,46 @@ struct ExpandCtx<'a> {
     nesting: Vec<NestingState>,
 }
 
-fn expand_subtree(ctx: &mut ExpandCtx, template: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {
+fn expand_subtree(ctx: &mut ExpandCtx, template: &tt::Subtree) -> ExpandResult<tt::Subtree> {
     let mut buf: Vec<tt::TokenTree> = Vec::new();
+    let mut err = None;
     for op in parse_template(template) {
-        match op? {
+        let op = match op {
+            Ok(op) => op,
+            Err(e) => {
+                err = Some(e);
+                break;
+            }
+        };
+        match op {
             Op::TokenTree(tt @ tt::TokenTree::Leaf(..)) => buf.push(tt.clone()),
             Op::TokenTree(tt::TokenTree::Subtree(tt)) => {
-                let tt = expand_subtree(ctx, tt)?;
+                let ExpandResult(tt, e) = expand_subtree(ctx, tt);
+                err = err.or(e);
                 buf.push(tt.into());
             }
             Op::Var { name, kind: _ } => {
-                let fragment = expand_var(ctx, name)?;
+                let ExpandResult(fragment, e) = expand_var(ctx, name);
+                err = err.or(e);
                 push_fragment(&mut buf, fragment);
             }
             Op::Repeat { subtree, kind, separator } => {
-                let fragment = expand_repeat(ctx, subtree, kind, separator)?;
+                let ExpandResult(fragment, e) = expand_repeat(ctx, subtree, kind, separator);
+                err = err.or(e);
                 push_fragment(&mut buf, fragment)
             }
         }
     }
-    Ok(tt::Subtree { delimiter: template.delimiter, token_trees: buf })
+    ExpandResult(tt::Subtree { delimiter: template.delimiter, token_trees: buf }, err)
 }
 
-fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> Result<Fragment, ExpandError> {
-    let res = if v == "crate" {
+fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> ExpandResult<Fragment> {
+    if v == "crate" {
         // We simply produce identifier `$crate` here. And it will be resolved when lowering ast to Path.
         let tt =
             tt::Leaf::from(tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() })
                 .into();
-        Fragment::Tokens(tt)
+        ExpandResult::ok(Fragment::Tokens(tt))
     } else if !ctx.bindings.contains(v) {
         // Note that it is possible to have a `$var` inside a macro which is not bound.
         // For example:
@@ -132,11 +141,13 @@ fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> Result<Fragment, ExpandError>
             ],
         }
         .into();
-        Fragment::Tokens(tt)
+        ExpandResult::ok(Fragment::Tokens(tt))
     } else {
-        ctx.bindings.get(&v, &mut ctx.nesting)?.clone()
-    };
-    Ok(res)
+        ctx.bindings.get(&v, &mut ctx.nesting).map_or_else(
+            |e| ExpandResult(Fragment::Tokens(tt::TokenTree::empty()), Some(e)),
+            |b| ExpandResult::ok(b.clone()),
+        )
+    }
 }
 
 fn expand_repeat(
@@ -144,17 +155,17 @@ fn expand_repeat(
     template: &tt::Subtree,
     kind: RepeatKind,
     separator: Option<Separator>,
-) -> Result<Fragment, ExpandError> {
+) -> ExpandResult<Fragment> {
     let mut buf: Vec<tt::TokenTree> = Vec::new();
     ctx.nesting.push(NestingState { idx: 0, at_end: false, hit: false });
     // Dirty hack to make macro-expansion terminate.
-    // This should be replaced by a propper macro-by-example implementation
+    // This should be replaced by a proper macro-by-example implementation
     let limit = 65536;
     let mut has_seps = 0;
     let mut counter = 0;
 
     loop {
-        let res = expand_subtree(ctx, template);
+        let ExpandResult(mut t, e) = expand_subtree(ctx, template);
         let nesting_state = ctx.nesting.last_mut().unwrap();
         if nesting_state.at_end || !nesting_state.hit {
             break;
@@ -172,10 +183,10 @@ fn expand_repeat(
             break;
         }
 
-        let mut t = match res {
-            Ok(t) => t,
-            Err(_) => continue,
-        };
+        if e.is_some() {
+            continue;
+        }
+
         t.delimiter = None;
         push_subtree(&mut buf, t);
 
@@ -209,14 +220,14 @@ fn expand_repeat(
         buf.pop();
     }
 
-    if RepeatKind::OneOrMore == kind && counter == 0 {
-        return Err(ExpandError::UnexpectedToken);
-    }
-
     // Check if it is a single token subtree without any delimiter
     // e.g {Delimiter:None> ['>'] /Delimiter:None>}
     let tt = tt::Subtree { delimiter: None, token_trees: buf }.into();
-    Ok(Fragment::Tokens(tt))
+
+    if RepeatKind::OneOrMore == kind && counter == 0 {
+        return ExpandResult(Fragment::Tokens(tt), Some(ExpandError::UnexpectedToken));
+    }
+    ExpandResult::ok(Fragment::Tokens(tt))
 }
 
 fn push_fragment(buf: &mut Vec<tt::TokenTree>, fragment: Fragment) {
diff --git a/crates/ra_mbe/src/tests.rs b/crates/ra_mbe/src/tests.rs
index 6d5d1e9e6..44f381938 100644
--- a/crates/ra_mbe/src/tests.rs
+++ b/crates/ra_mbe/src/tests.rs
@@ -1430,7 +1430,7 @@ impl MacroFixture {
         let (invocation_tt, _) =
             ast_to_token_tree(&macro_invocation.token_tree().unwrap()).unwrap();
 
-        self.rules.expand(&invocation_tt)
+        self.rules.expand(&invocation_tt).result()
     }
 
     fn assert_expand_err(&self, invocation: &str, err: &ExpandError) {
@@ -1662,5 +1662,5 @@ fn test_expand_bad_literal() {
         macro_rules! foo { ($i:literal) => {}; }
     "#,
     )
-    .assert_expand_err(r#"foo!(&k");"#, &ExpandError::NoMatchingRule);
+    .assert_expand_err(r#"foo!(&k");"#, &ExpandError::BindingError("".to_string()));
 }
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index b77b683b5..2335d99b3 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -61,7 +61,7 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         LIFETIME,
     ]);
 
-const EXPR_RECOVERY_SET: TokenSet = token_set![LET_KW];
+const EXPR_RECOVERY_SET: TokenSet = token_set![LET_KW, R_DOLLAR];
 
 pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)> {
     if let Some(m) = literal(p) {
diff --git a/crates/ra_tt/src/lib.rs b/crates/ra_tt/src/lib.rs
index 10f424aae..1e2fb8b91 100644
--- a/crates/ra_tt/src/lib.rs
+++ b/crates/ra_tt/src/lib.rs
@@ -40,6 +40,12 @@ pub enum TokenTree {
 }
 impl_froms!(TokenTree: Leaf, Subtree);
 
+impl TokenTree {
+    pub fn empty() -> Self {
+        TokenTree::Subtree(Subtree::default())
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Leaf {
     Literal(Literal),
diff --git a/editors/code/src/commands/server_version.ts b/editors/code/src/commands/server_version.ts
index c4d84b443..83b1acf67 100644
--- a/editors/code/src/commands/server_version.ts
+++ b/editors/code/src/commands/server_version.ts
@@ -5,7 +5,7 @@ import { spawnSync } from 'child_process';
 
 export function serverVersion(ctx: Ctx): Cmd {
     return async () => {
-        const binaryPath = await ensureServerBinary(ctx.config);
+        const binaryPath = await ensureServerBinary(ctx.config, ctx.state);
 
         if (binaryPath == null) {
             throw new Error(
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index f63e1d20e..bd8096dd6 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -182,13 +182,6 @@ export class Config {
         return this.createGithubReleaseSource("rust-analyzer.vsix", NIGHTLY_TAG);
     }
 
-    readonly installedNightlyExtensionReleaseDate = new DateStorage(
-        "installed-nightly-extension-release-date",
-        this.ctx.globalState
-    );
-    readonly serverReleaseDate = new DateStorage("server-release-date", this.ctx.globalState);
-    readonly serverReleaseTag = new Storage<null | string>("server-release-tag", this.ctx.globalState, null);
-
     // We don't do runtime config validation here for simplicity. More on stackoverflow:
     // https://stackoverflow.com/questions/60135780/what-is-the-best-way-to-type-check-the-configuration-for-vscode-extension
 
@@ -232,37 +225,3 @@ export class Config {
     // for internal use
     get withSysroot() { return this.cfg.get("withSysroot", true) as boolean; }
 }
-
-export class Storage<T> {
-    constructor(
-        private readonly key: string,
-        private readonly storage: vscode.Memento,
-        private readonly defaultVal: T
-    ) { }
-
-    get(): T {
-        const val = this.storage.get(this.key, this.defaultVal);
-        log.debug(this.key, "==", val);
-        return val;
-    }
-    async set(val: T) {
-        log.debug(this.key, "=", val);
-        await this.storage.update(this.key, val);
-    }
-}
-export class DateStorage {
-    inner: Storage<null | string>;
-
-    constructor(key: string, storage: vscode.Memento) {
-        this.inner = new Storage(key, storage, null);
-    }
-
-    get(): null | Date {
-        const dateStr = this.inner.get();
-        return dateStr ? new Date(dateStr) : null;
-    }
-
-    async set(date: null | Date) {
-        await this.inner.set(date ? date.toString() : null);
-    }
-}
diff --git a/editors/code/src/ctx.ts b/editors/code/src/ctx.ts
index 25ef38aed..c929ab063 100644
--- a/editors/code/src/ctx.ts
+++ b/editors/code/src/ctx.ts
@@ -4,19 +4,21 @@ import * as lc from 'vscode-languageclient';
 import { Config } from './config';
 import { createClient } from './client';
 import { isRustEditor, RustEditor } from './util';
+import { PersistentState } from './persistent_state';
 
 export class Ctx {
     private constructor(
         readonly config: Config,
+        readonly state: PersistentState,
         private readonly extCtx: vscode.ExtensionContext,
         readonly client: lc.LanguageClient
     ) {
 
     }
 
-    static async create(config: Config, extCtx: vscode.ExtensionContext, serverPath: string): Promise<Ctx> {
+    static async create(config: Config, state: PersistentState, extCtx: vscode.ExtensionContext, serverPath: string): Promise<Ctx> {
         const client = await createClient(config, serverPath);
-        const res = new Ctx(config, extCtx, client);
+        const res = new Ctx(config, state, extCtx, client);
         res.pushCleanup(client.start());
         await client.onReady();
         return res;
diff --git a/editors/code/src/installation/extension.ts b/editors/code/src/installation/extension.ts
index eea6fded2..a1db96f05 100644
--- a/editors/code/src/installation/extension.ts
+++ b/editors/code/src/installation/extension.ts
@@ -7,6 +7,7 @@ import { Config, UpdatesChannel } from "../config";
 import { ArtifactReleaseInfo, ArtifactSource } from "./interfaces";
 import { downloadArtifactWithProgressUi } from "./downloads";
 import { fetchArtifactReleaseInfo } from "./fetch_artifact_release_info";
+import { PersistentState } from "../persistent_state";
 
 const HEURISTIC_NIGHTLY_RELEASE_PERIOD_IN_HOURS = 25;
 
@@ -14,7 +15,7 @@ const HEURISTIC_NIGHTLY_RELEASE_PERIOD_IN_HOURS = 25;
  * Installs `stable` or latest `nightly` version or does nothing if the current
  * extension version is what's needed according to `desiredUpdateChannel`.
  */
-export async function ensureProperExtensionVersion(config: Config): Promise<never | void> {
+export async function ensureProperExtensionVersion(config: Config, state: PersistentState): Promise<never | void> {
     // User has built lsp server from sources, she should manage updates manually
     if (config.serverSource?.type === ArtifactSource.Type.ExplicitPath) return;
 
@@ -23,7 +24,7 @@ export async function ensureProperExtensionVersion(config: Config): Promise<neve
 
     if (currentUpdChannel === UpdatesChannel.Stable) {
         // Release date is present only when we are on nightly
-        await config.installedNightlyExtensionReleaseDate.set(null);
+        await state.installedNightlyExtensionReleaseDate.set(null);
     }
 
     if (desiredUpdChannel === UpdatesChannel.Stable) {
@@ -39,10 +40,10 @@ export async function ensureProperExtensionVersion(config: Config): Promise<neve
     if (currentUpdChannel === UpdatesChannel.Stable) {
         if (!await askToDownloadProperExtensionVersion(config)) return;
 
-        return await tryDownloadNightlyExtension(config);
+        return await tryDownloadNightlyExtension(config, state);
     }
 
-    const currentExtReleaseDate = config.installedNightlyExtensionReleaseDate.get();
+    const currentExtReleaseDate = state.installedNightlyExtensionReleaseDate.get();
 
     if (currentExtReleaseDate === null) {
         void vscode.window.showErrorMessage(
@@ -66,9 +67,9 @@ export async function ensureProperExtensionVersion(config: Config): Promise<neve
         return;
     }
 
-    await tryDownloadNightlyExtension(config, releaseInfo => {
+    await tryDownloadNightlyExtension(config, state, releaseInfo => {
         assert(
-            currentExtReleaseDate.getTime() === config.installedNightlyExtensionReleaseDate.get()?.getTime(),
+            currentExtReleaseDate.getTime() === state.installedNightlyExtensionReleaseDate.get()?.getTime(),
             "Other active VSCode instance has reinstalled the extension"
         );
 
@@ -111,6 +112,7 @@ async function askToDownloadProperExtensionVersion(config: Config, reason = "")
  */
 const tryDownloadNightlyExtension = notReentrant(async (
     config: Config,
+    state: PersistentState,
     shouldDownload: (releaseInfo: ArtifactReleaseInfo) => boolean = () => true
 ): Promise<never | void> => {
     const vsixSource = config.nightlyVsixSource;
@@ -124,7 +126,7 @@ const tryDownloadNightlyExtension = notReentrant(async (
         const vsixPath = path.join(vsixSource.dir, vsixSource.file);
 
         await vscodeInstallExtensionFromVsix(vsixPath);
-        await config.installedNightlyExtensionReleaseDate.set(releaseInfo.releaseDate);
+        await state.installedNightlyExtensionReleaseDate.set(releaseInfo.releaseDate);
         await fs.unlink(vsixPath);
 
         await vscodeReloadWindow(); // never returns
diff --git a/editors/code/src/installation/server.ts b/editors/code/src/installation/server.ts
index 05730a778..05d326131 100644
--- a/editors/code/src/installation/server.ts
+++ b/editors/code/src/installation/server.ts
@@ -7,8 +7,9 @@ import { fetchArtifactReleaseInfo } from "./fetch_artifact_release_info";
 import { downloadArtifactWithProgressUi } from "./downloads";
 import { log, assert, notReentrant } from "../util";
 import { Config, NIGHTLY_TAG } from "../config";
+import { PersistentState } from "../persistent_state";
 
-export async function ensureServerBinary(config: Config): Promise<null | string> {
+export async function ensureServerBinary(config: Config, state: PersistentState): Promise<null | string> {
     const source = config.serverSource;
 
     if (!source) {
@@ -37,7 +38,7 @@ export async function ensureServerBinary(config: Config): Promise<null | string>
             return null;
         }
         case ArtifactSource.Type.GithubRelease: {
-            if (!shouldDownloadServer(source, config)) {
+            if (!shouldDownloadServer(state, source)) {
                 return path.join(source.dir, source.file);
             }
 
@@ -50,24 +51,24 @@ export async function ensureServerBinary(config: Config): Promise<null | string>
                 if (userResponse !== "Download now") return null;
             }
 
-            return await downloadServer(source, config);
+            return await downloadServer(state, source);
         }
     }
 }
 
 function shouldDownloadServer(
+    state: PersistentState,
     source: ArtifactSource.GithubRelease,
-    config: Config
 ): boolean {
     if (!isBinaryAvailable(path.join(source.dir, source.file))) return true;
 
     const installed = {
-        tag: config.serverReleaseTag.get(),
-        date: config.serverReleaseDate.get()
+        tag: state.serverReleaseTag.get(),
+        date: state.serverReleaseDate.get()
     };
     const required = {
         tag: source.tag,
-        date: config.installedNightlyExtensionReleaseDate.get()
+        date: state.installedNightlyExtensionReleaseDate.get()
     };
 
     log.debug("Installed server:", installed, "required:", required);
@@ -86,16 +87,16 @@ function shouldDownloadServer(
  * Enforcing no reentrancy for this is best-effort.
  */
 const downloadServer = notReentrant(async (
+    state: PersistentState,
     source: ArtifactSource.GithubRelease,
-    config: Config,
 ): Promise<null | string> => {
     try {
         const releaseInfo = await fetchArtifactReleaseInfo(source.repo, source.file, source.tag);
 
         await downloadArtifactWithProgressUi(releaseInfo, source.file, source.dir, "language server");
         await Promise.all([
-            config.serverReleaseTag.set(releaseInfo.releaseName),
-            config.serverReleaseDate.set(releaseInfo.releaseDate)
+            state.serverReleaseTag.set(releaseInfo.releaseName),
+            state.serverReleaseDate.set(releaseInfo.releaseDate)
         ]);
     } catch (err) {
         log.downloadError(err, "language server", source.repo.name);
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index bd4661a36..94ecd4dab 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -9,6 +9,7 @@ import { ensureServerBinary } from './installation/server';
 import { Config } from './config';
 import { log } from './util';
 import { ensureProperExtensionVersion } from './installation/extension';
+import { PersistentState } from './persistent_state';
 
 let ctx: Ctx | undefined;
 
@@ -34,13 +35,14 @@ export async function activate(context: vscode.ExtensionContext) {
     context.subscriptions.push(defaultOnEnter);
 
     const config = new Config(context);
+    const state = new PersistentState(context);
 
-    vscode.workspace.onDidChangeConfiguration(() => ensureProperExtensionVersion(config).catch(log.error));
+    vscode.workspace.onDidChangeConfiguration(() => ensureProperExtensionVersion(config, state).catch(log.error));
 
     // Don't await the user response here, otherwise we will block the lsp server bootstrap
-    void ensureProperExtensionVersion(config).catch(log.error);
+    void ensureProperExtensionVersion(config, state).catch(log.error);
 
-    const serverPath = await ensureServerBinary(config);
+    const serverPath = await ensureServerBinary(config, state);
 
     if (serverPath == null) {
         throw new Error(
@@ -53,7 +55,7 @@ export async function activate(context: vscode.ExtensionContext) {
     // registers its `onDidChangeDocument` handler before us.
     //
     // This a horribly, horribly wrong way to deal with this problem.
-    ctx = await Ctx.create(config, context, serverPath);
+    ctx = await Ctx.create(config, state, context, serverPath);
 
     // Commands which invokes manually via command palette, shortcut, etc.
     ctx.registerCommand('reload', (ctx) => {
diff --git a/editors/code/src/persistent_state.ts b/editors/code/src/persistent_state.ts
new file mode 100644
index 000000000..13095b806
--- /dev/null
+++ b/editors/code/src/persistent_state.ts
@@ -0,0 +1,49 @@
+import * as vscode from 'vscode';
+import { log } from "./util";
+
+export class PersistentState {
+    constructor(private readonly ctx: vscode.ExtensionContext) {
+    }
+
+    readonly installedNightlyExtensionReleaseDate = new DateStorage(
+        "installed-nightly-extension-release-date",
+        this.ctx.globalState
+    );
+    readonly serverReleaseDate = new DateStorage("server-release-date", this.ctx.globalState);
+    readonly serverReleaseTag = new Storage<null | string>("server-release-tag", this.ctx.globalState, null);
+}
+
+
+export class Storage<T> {
+    constructor(
+        private readonly key: string,
+        private readonly storage: vscode.Memento,
+        private readonly defaultVal: T
+    ) { }
+
+    get(): T {
+        const val = this.storage.get(this.key, this.defaultVal);
+        log.debug(this.key, "==", val);
+        return val;
+    }
+    async set(val: T) {
+        log.debug(this.key, "=", val);
+        await this.storage.update(this.key, val);
+    }
+}
+export class DateStorage {
+    inner: Storage<null | string>;
+
+    constructor(key: string, storage: vscode.Memento) {
+        this.inner = new Storage(key, storage, null);
+    }
+
+    get(): null | Date {
+        const dateStr = this.inner.get();
+        return dateStr ? new Date(dateStr) : null;
+    }
+
+    async set(date: null | Date) {
+        await this.inner.set(date ? date.toString() : null);
+    }
+}
diff --git a/xtask/tests/tidy-tests/cli.rs b/xtask/tests/tidy-tests/cli.rs
index f9ca45292..f5b00a8b8 100644
--- a/xtask/tests/tidy-tests/cli.rs
+++ b/xtask/tests/tidy-tests/cli.rs
@@ -1,7 +1,6 @@
-use walkdir::WalkDir;
 use xtask::{
     codegen::{self, Mode},
-    project_root, run_rustfmt,
+    run_rustfmt,
 };
 
 #[test]
@@ -31,25 +30,3 @@ fn check_code_formatting() {
         panic!("{}. Please format the code by running `cargo format`", error);
     }
 }
-
-#[test]
-fn no_todo() {
-    WalkDir::new(project_root().join("crates")).into_iter().for_each(|e| {
-        let e = e.unwrap();
-        if e.path().extension().map(|it| it != "rs").unwrap_or(true) {
-            return;
-        }
-        if e.path().ends_with("tests/cli.rs") {
-            return;
-        }
-        let text = std::fs::read_to_string(e.path()).unwrap();
-        if text.contains("TODO") || text.contains("TOOD") || text.contains("todo!") {
-            panic!(
-                "\nTODO markers should not be committed to the master branch,\n\
-                 use FIXME instead\n\
-                 {}\n",
-                e.path().display(),
-            )
-        }
-    })
-}
diff --git a/xtask/tests/tidy-tests/docs.rs b/xtask/tests/tidy-tests/docs.rs
deleted file mode 100644
index 62c4f8441..000000000
--- a/xtask/tests/tidy-tests/docs.rs
+++ /dev/null
@@ -1,106 +0,0 @@
-use std::{collections::HashMap, fs, io::prelude::*, io::BufReader, path::Path};
-
-use anyhow::Context;
-use walkdir::{DirEntry, WalkDir};
-use xtask::project_root;
-
-fn is_exclude_dir(p: &Path) -> bool {
-    // Test hopefully don't really need comments, and for assists we already
-    // have special comments which are source of doc tests and user docs.
-    let exclude_dirs = ["tests", "test_data", "handlers"];
-    let mut cur_path = p;
-    while let Some(path) = cur_path.parent() {
-        if exclude_dirs.iter().any(|dir| path.ends_with(dir)) {
-            return true;
-        }
-        cur_path = path;
-    }
-
-    false
-}
-
-fn is_exclude_file(d: &DirEntry) -> bool {
-    let file_names = ["tests.rs"];
-
-    d.file_name().to_str().map(|f_n| file_names.iter().any(|name| *name == f_n)).unwrap_or(false)
-}
-
-fn is_hidden(entry: &DirEntry) -> bool {
-    entry.file_name().to_str().map(|s| s.starts_with('.')).unwrap_or(false)
-}
-
-#[test]
-fn no_docs_comments() {
-    let crates = project_root().join("crates");
-    let iter = WalkDir::new(crates);
-    let mut missing_docs = Vec::new();
-    let mut contains_fixme = Vec::new();
-    for f in iter.into_iter().filter_entry(|e| !is_hidden(e)) {
-        let f = f.unwrap();
-        if f.file_type().is_dir() {
-            continue;
-        }
-        if f.path().extension().map(|it| it != "rs").unwrap_or(false) {
-            continue;
-        }
-        if is_exclude_dir(f.path()) {
-            continue;
-        }
-        if is_exclude_file(&f) {
-            continue;
-        }
-        let mut reader = BufReader::new(fs::File::open(f.path()).unwrap());
-        let mut line = String::new();
-        reader
-            .read_line(&mut line)
-            .with_context(|| format!("Failed to read {}", f.path().display()))
-            .unwrap();
-
-        if line.starts_with("//!") {
-            if line.contains("FIXME") {
-                contains_fixme.push(f.path().to_path_buf())
-            }
-        } else {
-            missing_docs.push(f.path().display().to_string());
-        }
-    }
-    if !missing_docs.is_empty() {
-        panic!(
-            "\nMissing docs strings\n\n\
-             modules:\n{}\n\n",
-            missing_docs.join("\n")
-        )
-    }
-
-    let whitelist = [
-        "ra_db",
-        "ra_hir",
-        "ra_hir_expand",
-        "ra_ide",
-        "ra_mbe",
-        "ra_parser",
-        "ra_prof",
-        "ra_project_model",
-        "ra_syntax",
-        "ra_text_edit",
-        "ra_tt",
-        "ra_hir_ty",
-    ];
-
-    let mut has_fixmes = whitelist.iter().map(|it| (*it, false)).collect::<HashMap<&str, bool>>();
-    'outer: for path in contains_fixme {
-        for krate in whitelist.iter() {
-            if path.components().any(|it| it.as_os_str() == *krate) {
-                has_fixmes.insert(krate, true);
-                continue 'outer;
-            }
-        }
-        panic!("FIXME doc in a fully-documented crate: {}", path.display())
-    }
-
-    for (krate, has_fixme) in has_fixmes.iter() {
-        if !has_fixme {
-            panic!("crate {} is fully documented, remove it from the white list", krate)
-        }
-    }
-}
diff --git a/xtask/tests/tidy-tests/main.rs b/xtask/tests/tidy-tests/main.rs
index 56d1318d6..2d2d88bec 100644
--- a/xtask/tests/tidy-tests/main.rs
+++ b/xtask/tests/tidy-tests/main.rs
@@ -1,2 +1,145 @@
 mod cli;
-mod docs;
+
+use std::{
+    collections::HashMap,
+    path::{Path, PathBuf},
+};
+
+use walkdir::{DirEntry, WalkDir};
+use xtask::{not_bash::fs2, project_root};
+
+#[test]
+fn rust_files_are_tidy() {
+    let mut tidy_docs = TidyDocs::default();
+    for path in rust_files() {
+        let text = fs2::read_to_string(&path).unwrap();
+        check_todo(&path, &text);
+        tidy_docs.visit(&path, &text);
+    }
+    tidy_docs.finish();
+}
+
+fn check_todo(path: &Path, text: &str) {
+    if path.ends_with("tests/cli.rs") {
+        return;
+    }
+    if text.contains("TODO") || text.contains("TOOD") || text.contains("todo!") {
+        panic!(
+            "\nTODO markers should not be committed to the master branch,\n\
+             use FIXME instead\n\
+             {}\n",
+            path.display(),
+        )
+    }
+}
+
+#[derive(Default)]
+struct TidyDocs {
+    missing_docs: Vec<String>,
+    contains_fixme: Vec<PathBuf>,
+}
+
+impl TidyDocs {
+    fn visit(&mut self, path: &Path, text: &str) {
+        if is_exclude_dir(path) || is_exclude_file(path) {
+            return;
+        }
+
+        let first_line = match text.lines().next() {
+            Some(it) => it,
+            None => return,
+        };
+
+        if first_line.starts_with("//!") {
+            if first_line.contains("FIXME") {
+                self.contains_fixme.push(path.to_path_buf())
+            }
+        } else {
+            self.missing_docs.push(path.display().to_string());
+        }
+
+        fn is_exclude_dir(p: &Path) -> bool {
+            // Test hopefully don't really need comments, and for assists we already
+            // have special comments which are source of doc tests and user docs.
+            let exclude_dirs = ["tests", "test_data", "handlers"];
+            let mut cur_path = p;
+            while let Some(path) = cur_path.parent() {
+                if exclude_dirs.iter().any(|dir| path.ends_with(dir)) {
+                    return true;
+                }
+                cur_path = path;
+            }
+
+            false
+        }
+
+        fn is_exclude_file(d: &Path) -> bool {
+            let file_names = ["tests.rs"];
+
+            d.file_name()
+                .unwrap_or_default()
+                .to_str()
+                .map(|f_n| file_names.iter().any(|name| *name == f_n))
+                .unwrap_or(false)
+        }
+    }
+
+    fn finish(self) {
+        if !self.missing_docs.is_empty() {
+            panic!(
+                "\nMissing docs strings\n\n\
+                 modules:\n{}\n\n",
+                self.missing_docs.join("\n")
+            )
+        }
+
+        let whitelist = [
+            "ra_db",
+            "ra_hir",
+            "ra_hir_expand",
+            "ra_ide",
+            "ra_mbe",
+            "ra_parser",
+            "ra_prof",
+            "ra_project_model",
+            "ra_syntax",
+            "ra_text_edit",
+            "ra_tt",
+            "ra_hir_ty",
+        ];
+
+        let mut has_fixmes =
+            whitelist.iter().map(|it| (*it, false)).collect::<HashMap<&str, bool>>();
+        'outer: for path in self.contains_fixme {
+            for krate in whitelist.iter() {
+                if path.components().any(|it| it.as_os_str() == *krate) {
+                    has_fixmes.insert(krate, true);
+                    continue 'outer;
+                }
+            }
+            panic!("FIXME doc in a fully-documented crate: {}", path.display())
+        }
+
+        for (krate, has_fixme) in has_fixmes.iter() {
+            if !has_fixme {
+                panic!("crate {} is fully documented, remove it from the white list", krate)
+            }
+        }
+    }
+}
+
+fn rust_files() -> impl Iterator<Item = PathBuf> {
+    let crates = project_root().join("crates");
+    let iter = WalkDir::new(crates);
+    return iter
+        .into_iter()
+        .filter_entry(|e| !is_hidden(e))
+        .map(|e| e.unwrap())
+        .filter(|e| !e.file_type().is_dir())
+        .map(|e| e.into_path())
+        .filter(|path| path.extension().map(|it| it == "rs").unwrap_or(false));
+
+    fn is_hidden(entry: &DirEntry) -> bool {
+        entry.file_name().to_str().map(|s| s.starts_with('.')).unwrap_or(false)
+    }
+}