5 files changed, 101 insertions, 26 deletions

diff --git a/crates/ra_hir_ty/src/_match.rs b/crates/ra_hir_ty/src/_match.rs
index 779e78574..149f65042 100644
--- a/crates/ra_hir_ty/src/_match.rs
+++ b/crates/ra_hir_ty/src/_match.rs
@@ -573,14 +573,20 @@ pub(crate) fn is_useful(
     matrix: &Matrix,
     v: &PatStack,
 ) -> MatchCheckResult<Usefulness> {
-    // Handle the special case of enums with no variants. In that case, no match
-    // arm is useful.
-    if let Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(AdtId::EnumId(enum_id)), .. }) =
-        cx.infer[cx.match_expr].strip_references()
-    {
-        if cx.db.enum_data(*enum_id).variants.is_empty() {
+    // Handle two special cases:
+    // - enum with no variants
+    // - `!` type
+    // In those cases, no match arm is useful.
+    match cx.infer[cx.match_expr].strip_references() {
+        Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(AdtId::EnumId(enum_id)), .. }) => {
+            if cx.db.enum_data(*enum_id).variants.is_empty() {
+                return Ok(Usefulness::NotUseful);
+            }
+        }
+        Ty::Apply(ApplicationTy { ctor: TypeCtor::Never, .. }) => {
             return Ok(Usefulness::NotUseful);
         }
+        _ => (),
     }
 
     if v.is_empty() {
@@ -1918,6 +1924,17 @@ mod tests {
     }
 
     #[test]
+    fn type_never() {
+        let content = r"
+            fn test_fn(never: !) {
+                match never {}
+            }
+        ";
+
+        check_no_diagnostic(content);
+    }
+
+    #[test]
     fn enum_never_ref() {
         let content = r"
             enum Never {}
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index 588d81282..d60732e19 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -361,6 +361,33 @@ fn no_such_field_with_feature_flag_diagnostics() {
 }
 
 #[test]
+fn no_such_field_enum_with_feature_flag_diagnostics() {
+    let diagnostics = TestDB::with_files(
+        r#"
+        //- /lib.rs crate:foo cfg:feature=foo
+        enum Foo {
+            #[cfg(not(feature = "foo"))]
+            Buz,
+            #[cfg(feature = "foo")]
+            Bar,
+            Baz
+        }
+
+        fn test_fn(f: Foo) {
+            match f {
+                Foo::Bar => {},
+                Foo::Baz => {},
+            }
+        }
+        "#,
+    )
+    .diagnostics()
+    .0;
+
+    assert_snapshot!(diagnostics, @r###""###);
+}
+
+#[test]
 fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
     let diagnostics = TestDB::with_files(
         r#"
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index 29e38a06c..07398ddcc 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -269,7 +269,7 @@ fn test() { S.foo()<|>; }
 }
 
 #[test]
-fn infer_impl_items_generated_by_macros() {
+fn infer_assoc_items_generated_by_macros() {
     let t = type_at(
         r#"
 //- /main.rs
@@ -288,7 +288,7 @@ fn test() { S.foo()<|>; }
 }
 
 #[test]
-fn infer_impl_items_generated_by_macros_chain() {
+fn infer_assoc_items_generated_by_macros_chain() {
     let t = type_at(
         r#"
 //- /main.rs
diff --git a/crates/ra_hir_ty/src/tests/regression.rs b/crates/ra_hir_ty/src/tests/regression.rs
index 8a1292c7a..115ad8328 100644
--- a/crates/ra_hir_ty/src/tests/regression.rs
+++ b/crates/ra_hir_ty/src/tests/regression.rs
@@ -535,6 +535,35 @@ fn foo(b: Bar) {
 }
 
 #[test]
+fn issue_4235_name_conflicts() {
+    assert_snapshot!(
+        infer(r#"
+struct FOO {}
+static FOO:FOO = FOO {};
+
+impl FOO {
+    fn foo(&self) {}
+}
+
+fn main() {
+    let a = &FOO;
+    a.foo();
+}
+"#), @r###"
+    32..38 'FOO {}': FOO
+    64..68 'self': &FOO
+    70..72 '{}': ()
+    86..120 '{     ...o(); }': ()
+    96..97 'a': &FOO
+    100..104 '&FOO': &FOO
+    101..104 'FOO': FOO
+    110..111 'a': &FOO
+    110..117 'a.foo()': ()
+"###
+    );
+}
+
+#[test]
 fn issue_4053_diesel_where_clauses() {
     assert_snapshot!(
         infer(r#"
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index e555c879a..9d32cbc7a 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -2055,7 +2055,7 @@ fn test<I: Iterator<Item: Iterator<Item = u32>>>() {
 #[test]
 fn proc_macro_server_types() {
     assert_snapshot!(
-        infer_with_mismatches(r#"
+        infer(r#"
 macro_rules! with_api {
     ($S:ident, $self:ident, $m:ident) => {
         $m! {
@@ -2069,9 +2069,9 @@ macro_rules! with_api {
 }
 macro_rules! associated_item {
     (type TokenStream) =>
-        (type TokenStream: 'static + Clone;);
+        (type TokenStream: 'static;);
     (type Group) =>
-        (type Group: 'static + Clone;);
+        (type Group: 'static;);
     ($($item:tt)*) => ($($item)*;)
 }
 macro_rules! declare_server_traits {
@@ -2083,21 +2083,23 @@ macro_rules! declare_server_traits {
         }
 
         $(pub trait $name: Types {
-            $(associated_item!(fn $method(&mut self, $($arg: $arg_ty),*) $(-> $ret_ty)?);)*
+            $(associated_item!(fn $method($($arg: $arg_ty),*) $(-> $ret_ty)?);)*
         })*
 
         pub trait Server: Types $(+ $name)* {}
         impl<S: Types $(+ $name)*> Server for S {}
     }
 }
+
 with_api!(Self, self_, declare_server_traits);
-struct Group {}
-struct TokenStream {}
+struct G {}
+struct T {}
 struct Rustc;
 impl Types for Rustc {
-    type TokenStream = TokenStream;
-    type Group = Group;
+    type TokenStream = T;
+    type Group = G;
 }
+
 fn make<T>() -> T { loop {} }
 impl TokenStream for Rustc {
     fn new() -> Self::TokenStream {
@@ -2105,17 +2107,17 @@ impl TokenStream for Rustc {
         make()
     }
 }
-"#, true),
+"#),
         @r###"
-    1115..1126 '{ loop {} }': T
-    1117..1124 'loop {}': !
-    1122..1124 '{}': ()
-    1190..1253 '{     ...     }': {unknown}
-    1204..1209 'group': {unknown}
-    1225..1229 'make': fn make<{unknown}>() -> {unknown}
-    1225..1231 'make()': {unknown}
-    1241..1245 'make': fn make<{unknown}>() -> {unknown}
-    1241..1247 'make()': {unknown}
+    1062..1073 '{ loop {} }': T
+    1064..1071 'loop {}': !
+    1069..1071 '{}': ()
+    1137..1200 '{     ...     }': T
+    1151..1156 'group': G
+    1172..1176 'make': fn make<G>() -> G
+    1172..1178 'make()': G
+    1188..1192 'make': fn make<T>() -> T
+    1188..1194 'make()': T
     "###
     );
 }