Avoid ?Sized local E0282 errors to provide better output and suggestions

Author: estebank

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1505,7 +1505,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
                 // begin with in those cases.
                 if self.tcx.lang_items().sized_trait() == Some(data.trait_ref.def_id) {
                     self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0282, &[])
-                        .emit();
+                        .delay_as_bug();
                     return;
                 }
                 // Try to find possible types that would satisfy the bounds in the type param to

src/test/ui/async-await/issues/issue-65159.rs

@@ -5,7 +5,6 @@
 async fn copy() -> Result<()> //~ ERROR wrong number of type arguments
 {
     Ok(())
-    //~^ ERROR type annotations needed
 }
 
 fn main() { }

src/test/ui/async-await/issues/issue-65159.stderr

@@ -4,13 +4,6 @@ error[E0107]: wrong number of type arguments: expected 2, found 1
 LL | async fn copy() -> Result<()>
    |                    ^^^^^^^^^^ expected 2 type arguments
 
-error[E0282]: type annotations needed
-  --> $DIR/issue-65159.rs:7:5
-   |
-LL |     Ok(())
-   |     ^^ cannot infer type for type parameter `E` declared on the enum `Result`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0107, E0282.
-For more information about an error, try `rustc --explain E0107`.
+For more information about this error, try `rustc --explain E0107`.

src/test/ui/closures/issue-52437.rs

@@ -1,6 +1,5 @@
 fn main() {
     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]
     //~^ ERROR: invalid label name `'static`
-    //~| ERROR: type annotations needed
     //~| ERROR mismatched types
 }

src/test/ui/closures/issue-52437.stderr

@@ -4,12 +4,6 @@ error: invalid label name `'static`
 LL |     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]
    |             ^^^^^^^
 
-error[E0282]: type annotations needed
-  --> $DIR/issue-52437.rs:2:30
-   |
-LL |     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]
-   |                              ^ consider giving this closure parameter a type
-
 error[E0308]: mismatched types
   --> $DIR/issue-52437.rs:2:5
    |
@@ -18,7 +12,6 @@ LL | fn main() {
 LL |     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found array `[(); _]`
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0282, E0308.
-For more information about an error, try `rustc --explain E0282`.
+For more information about this error, try `rustc --explain E0308`.

src/test/ui/consts/issue-52432.rs

@@ -3,7 +3,6 @@
 fn main() {
     [(); &(static |x| {}) as *const _ as usize];
     //~^ ERROR: closures cannot be static
-    //~| ERROR: type annotations needed
     [(); &(static || {}) as *const _ as usize];
     //~^ ERROR: closures cannot be static
     //~| ERROR evaluation of constant value failed

src/test/ui/consts/issue-52432.stderr

@@ -5,24 +5,18 @@ LL |     [(); &(static |x| {}) as *const _ as usize];
    |            ^^^^^^^^^^
 
 error[E0697]: closures cannot be static
-  --> $DIR/issue-52432.rs:7:12
+  --> $DIR/issue-52432.rs:6:12
    |
 LL |     [(); &(static || {}) as *const _ as usize];
    |            ^^^^^^^^^
 
-error[E0282]: type annotations needed
-  --> $DIR/issue-52432.rs:4:20
-   |
-LL |     [(); &(static |x| {}) as *const _ as usize];
-   |                    ^ consider giving this closure parameter a type
-
 error[E0080]: evaluation of constant value failed
-  --> $DIR/issue-52432.rs:7:10
+  --> $DIR/issue-52432.rs:6:10
    |
 LL |     [(); &(static || {}) as *const _ as usize];
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ "pointer-to-integer cast" needs an rfc before being allowed inside constants
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0080, E0282, E0697.
+Some errors have detailed explanations: E0080, E0697.
 For more information about an error, try `rustc --explain E0080`.

src/test/ui/consts/issue-64662.rs

@@ -1,6 +1,6 @@
 enum Foo {
     A = foo(), //~ ERROR: type annotations needed
-    B = foo(), //~ ERROR: type annotations needed
+    B = foo(), // We don't emit an error here, but if the one above is fixed, we will.
 }
 
 const fn foo<T>() -> isize {

src/test/ui/consts/issue-64662.stderr

@@ -4,12 +4,6 @@ error[E0282]: type annotations needed
 LL |     A = foo(),
    |         ^^^ cannot infer type for type parameter `T` declared on the function `foo`
 
-error[E0282]: type annotations needed
-  --> $DIR/issue-64662.rs:3:9
-   |
-LL |     B = foo(),
-   |         ^^^ cannot infer type for type parameter `T` declared on the function `foo`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0282`.

src/test/ui/error-codes/E0401.stderr

@@ -32,13 +32,22 @@ LL |         fn helper(sel: &Self) -> u8 {
    |                         use of generic parameter from outer function
    |                         use a type here instead
 
-error[E0282]: type annotations needed
+error[E0283]: type annotations needed
   --> $DIR/E0401.rs:11:5
    |
+LL |     fn bfnr<U, V: Baz<U>, W: Fn()>(y: T) {
+   |                   ------ required by this bound in `bfnr`
+...
 LL |     bfnr(x);
-   |     ^^^^ cannot infer type for type parameter `U` declared on the function `bfnr`
+   |     ^^^^ cannot infer type for type parameter `V` declared on the function `bfnr`
+   |
+   = note: cannot satisfy `_: Baz<_>`
+help: consider specifying the type arguments in the function call
+   |
+LL |     bfnr::<U, V, W>(x);
+   |         ^^^^^^^^^^^
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0282, E0401.
-For more information about an error, try `rustc --explain E0282`.
+Some errors have detailed explanations: E0283, E0401.
+For more information about an error, try `rustc --explain E0283`.