Fix spacing of expected/found notes without a label

Author: estebank

src/librustc_errors/diagnostic.rs

@@ -193,9 +193,18 @@ impl Diagnostic {
         expected_extra: &dyn fmt::Display,
         found_extra: &dyn fmt::Display,
     ) -> &mut Self {
-        let expected_label = format!("expected {}", expected_label);
-
-        let found_label = format!("found {}", found_label);
+        let expected_label = expected_label.to_string();
+        let expected_label = if expected_label.is_empty() {
+            "expected".to_string()
+        } else {
+            format!("expected {}", expected_label)
+        };
+        let found_label = found_label.to_string();
+        let found_label = if found_label.is_empty() {
+            "found".to_string()
+        } else {
+            format!("found {}", found_label)
+        };
         let (found_padding, expected_padding) = if expected_label.len() > found_label.len() {
             (expected_label.len() - found_label.len(), 0)
         } else {

src/test/ui/associated-types/cache/project-fn-ret-invariant.transmute.stderr

@@ -14,16 +14,16 @@ note: ...so that the expression is assignable
    |
 LL |    bar(foo, x)
    |             ^
-   = note: expected  `Type<'_>`
-              found  `Type<'a>`
+   = note: expected `Type<'_>`
+              found `Type<'a>`
    = note: but, the lifetime must be valid for the static lifetime...
 note: ...so that the expression is assignable
   --> $DIR/project-fn-ret-invariant.rs:48:4
    |
 LL |    bar(foo, x)
    |    ^^^^^^^^^^^
-   = note: expected  `Type<'static>`
-              found  `Type<'_>`
+   = note: expected `Type<'static>`
+              found `Type<'_>`
 
 error: aborting due to previous error
 

src/test/ui/impl-header-lifetime-elision/dyn-trait.stderr

@@ -14,16 +14,16 @@ note: ...so that the expression is assignable
    |
 LL |     static_val(x);
    |                ^
-   = note: expected  `std::boxed::Box<dyn std::fmt::Debug>`
-              found  `std::boxed::Box<(dyn std::fmt::Debug + 'a)>`
+   = note: expected `std::boxed::Box<dyn std::fmt::Debug>`
+              found `std::boxed::Box<(dyn std::fmt::Debug + 'a)>`
    = note: but, the lifetime must be valid for the static lifetime...
 note: ...so that the types are compatible
   --> $DIR/dyn-trait.rs:20:5
    |
 LL |     static_val(x);
    |     ^^^^^^^^^^
-   = note: expected  `StaticTrait`
-              found  `StaticTrait`
+   = note: expected `StaticTrait`
+              found `StaticTrait`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-16683.stderr

@@ -26,8 +26,8 @@ note: ...so that the types are compatible
    |
 LL |         self.a();
    |              ^
-   = note: expected  `&'a Self`
-              found  `&Self`
+   = note: expected `&'a Self`
+              found `&Self`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-17758.stderr

@@ -27,8 +27,8 @@ note: ...so that the types are compatible
    |
 LL |         self.foo();
    |              ^^^
-   = note: expected  `&'a Self`
-              found  `&Self`
+   = note: expected `&'a Self`
+              found `&Self`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-20831-debruijn.stderr

@@ -117,8 +117,8 @@ note: ...so that the types are compatible
    |
 LL |     fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: expected  `Publisher<'_>`
-              found  `Publisher<'_>`
+   = note: expected `Publisher<'_>`
+              found `Publisher<'_>`
 
 error: aborting due to 4 previous errors
 

src/test/ui/issues/issue-52213.stderr

@@ -14,8 +14,8 @@ note: ...so that the types are compatible
    |
 LL |     match (&t,) {
    |           ^^^^^
-   = note: expected  `(&&(T,),)`
-              found  `(&&'a (T,),)`
+   = note: expected `(&&(T,),)`
+              found `(&&'a (T,),)`
 note: but, the lifetime must be valid for the lifetime `'b` as defined on the function body at 1:27...
   --> $DIR/issue-52213.rs:1:27
    |

src/test/ui/issues/issue-55796.stderr

@@ -20,8 +20,8 @@ note: ...so that the expression is assignable
    |
 LL |         Box::new(self.out_edges(u).map(|e| e.target()))
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: expected  `std::boxed::Box<(dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node> + 'static)>`
-              found  `std::boxed::Box<dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node>>`
+   = note: expected `std::boxed::Box<(dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node> + 'static)>`
+              found `std::boxed::Box<dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node>>`
 
 error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
   --> $DIR/issue-55796.rs:21:9
@@ -45,8 +45,8 @@ note: ...so that the expression is assignable
    |
 LL |         Box::new(self.in_edges(u).map(|e| e.target()))
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: expected  `std::boxed::Box<(dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node> + 'static)>`
-              found  `std::boxed::Box<dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node>>`
+   = note: expected `std::boxed::Box<(dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node> + 'static)>`
+              found `std::boxed::Box<dyn std::iter::Iterator<Item = <Self as Graph<'a>>::Node>>`
 
 error: aborting due to 2 previous errors
 

src/test/ui/nll/issue-55394.stderr

@@ -26,8 +26,8 @@ note: ...so that the expression is assignable
    |
 LL |         Foo { bar }
    |         ^^^^^^^^^^^
-   = note: expected  `Foo<'_>`
-              found  `Foo<'_>`
+   = note: expected `Foo<'_>`
+              found `Foo<'_>`
 
 error: aborting due to previous error
 

src/test/ui/nll/normalization-bounds-error.stderr

@@ -19,8 +19,8 @@ note: ...so that the types are compatible
    |
 LL | fn visit_seq<'d, 'a: 'd>() -> <&'a () as Visitor<'d>>::Value {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: expected  `Visitor<'d>`
-              found  `Visitor<'_>`
+   = note: expected `Visitor<'d>`
+              found `Visitor<'_>`
 
 error: aborting due to previous error