4 files changed, 34 insertions, 16 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/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 83f946eee..614c352a0 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -501,8 +501,8 @@ impl<'a> InferenceContext<'a> {
                 }
                 Literal::ByteString(..) => {
                     let byte_type = Ty::simple(TypeCtor::Int(Uncertain::Known(IntTy::u8())));
-                    let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type);
-                    Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type)
+                    let array_type = Ty::apply_one(TypeCtor::Array, byte_type);
+                    Ty::apply_one(TypeCtor::Ref(Mutability::Shared), array_type)
                 }
                 Literal::Char(..) => Ty::simple(TypeCtor::Char),
                 Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int((*ty).into())),
diff --git a/crates/ra_hir_ty/src/tests/method_resolution.rs b/crates/ra_hir_ty/src/tests/method_resolution.rs
index ab87f598a..67f964ab5 100644
--- a/crates/ra_hir_ty/src/tests/method_resolution.rs
+++ b/crates/ra_hir_ty/src/tests/method_resolution.rs
@@ -17,8 +17,8 @@ impl<T> [T] {
 #[lang = "slice_alloc"]
 impl<T> [T] {}
 
-fn test() {
-    <[_]>::foo(b"foo");
+fn test(x: &[u8]) {
+    <[_]>::foo(x);
 }
 "#),
         @r###"
@@ -26,10 +26,11 @@ fn test() {
     56..79 '{     ...     }': T
     66..73 'loop {}': !
     71..73 '{}': ()
-    133..160 '{     ...o"); }': ()
-    139..149 '<[_]>::foo': fn foo<u8>(&[u8]) -> u8
-    139..157 '<[_]>:..."foo")': u8
-    150..156 'b"foo"': &[u8]
+    131..132 'x': &[u8]
+    141..163 '{     ...(x); }': ()
+    147..157 '<[_]>::foo': fn foo<u8>(&[u8]) -> u8
+    147..160 '<[_]>::foo(x)': u8
+    158..159 'x': &[u8]
     "###
     );
 }
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index 3d3088965..e17a17900 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -414,7 +414,7 @@ fn test() {
     27..31 '5f32': f32
     37..41 '5f64': f64
     47..54 '"hello"': &str
-    60..68 'b"bytes"': &[u8]
+    60..68 'b"bytes"': &[u8; _]
     74..77 ''c'': char
     83..87 'b'b'': u8
     93..97 '3.14': f64
@@ -422,7 +422,7 @@ fn test() {
     113..118 'false': bool
     124..128 'true': bool
     134..202 'r#"   ...    "#': &str
-    208..218 'br#"yolo"#': &[u8]
+    208..218 'br#"yolo"#': &[u8; _]
     "###
     );
 }