Rollup merge of #131795 - compiler-errors:expectation, r=Nadrieril

Stop inverting expectation in normalization errors

We have some funky special case logic to invert the expectation and actual type for normalization errors depending on their cause code. IMO most of the error messages get better, except for `try {}` blocks' type expectations. I think that these need to be special cased in some other way, rather than via this hack.

Fixes #131763

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

@@ -1277,19 +1277,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     let normalized_term =
                         ocx.normalize(&obligation.cause, obligation.param_env, unnormalized_term);
 
-                    let is_normalized_term_expected = !matches!(
-                        obligation.cause.code().peel_derives(),
-                        ObligationCauseCode::WhereClause(..)
-                            | ObligationCauseCode::WhereClauseInExpr(..)
-                            | ObligationCauseCode::Coercion { .. }
-                    );
-
-                    let (expected, actual) = if is_normalized_term_expected {
-                        (normalized_term, data.term)
-                    } else {
-                        (data.term, normalized_term)
-                    };
-
                     // constrain inference variables a bit more to nested obligations from normalize so
                     // we can have more helpful errors.
                     //
@@ -1298,12 +1285,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     let _ = ocx.select_where_possible();
 
                     if let Err(new_err) =
-                        ocx.eq(&obligation.cause, obligation.param_env, expected, actual)
+                        ocx.eq(&obligation.cause, obligation.param_env, data.term, normalized_term)
                     {
                         (
                             Some((
                                 data.projection_term,
-                                is_normalized_term_expected,
+                                false,
                                 self.resolve_vars_if_possible(normalized_term),
                                 data.term,
                             )),
@@ -1444,12 +1431,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 &mut diag,
                 &obligation.cause,
                 secondary_span,
-                values.map(|(_, is_normalized_ty_expected, normalized_ty, expected_ty)| {
+                values.map(|(_, _, normalized_ty, expected_ty)| {
-                    infer::ValuePairs::Terms(ExpectedFound::new(
+                    infer::ValuePairs::Terms(ExpectedFound::new(true, expected_ty, normalized_ty))
-                        is_normalized_ty_expected,
-                        normalized_ty,
-                        expected_ty,
-                    ))
                 }),
                 err,
                 false,

tests/ui/associated-types/impl-trait-return-missing-constraint.stderr

@@ -2,18 +2,16 @@ error[E0271]: type mismatch resolving `<impl Bar as Foo>::Item == i32`
   --> $DIR/impl-trait-return-missing-constraint.rs:25:13
    |
 LL | fn bar() -> impl Bar {
-   |             -------- the expected opaque type
+   |             -------- the found opaque type
 ...
 LL | fn baz() -> impl Bar<Item = i32> {
-   |             ^^^^^^^^^^^^^^^^^^^^ expected associated type, found `i32`
+   |             ^^^^^^^^^^^^^^^^^^^^ expected `i32`, found associated type
 LL |
 LL |     bar()
    |     ----- return type was inferred to be `impl Bar` here
    |
-   = note: expected associated type `<impl Bar as Foo>::Item`
+   = note:         expected type `i32`
-                         found type `i32`
+           found associated type `<impl Bar as Foo>::Item`
-   = help: consider constraining the associated type `<impl Bar as Foo>::Item` to `i32` or calling a method that returns `<impl Bar as Foo>::Item`
-   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 help: consider constraining the associated type `<impl Bar as Foo>::Item` to `i32`
    |
 LL | fn bar() -> impl Bar<Item = i32> {

tests/ui/coroutine/type-mismatch-signature-deduction.stderr

@@ -22,10 +22,10 @@ error[E0271]: type mismatch resolving `<{coroutine@$DIR/type-mismatch-signature-
   --> $DIR/type-mismatch-signature-deduction.rs:5:13
    |
 LL | fn foo() -> impl Coroutine<Return = i32> {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Result<{integer}, _>`, found `i32`
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `Result<{integer}, _>`
    |
-   = note: expected enum `Result<{integer}, _>`
+   = note: expected type `i32`
-              found type `i32`
+              found enum `Result<{integer}, _>`
 
 error: aborting due to 2 previous errors
 

tests/ui/diagnostic_namespace/do_not_recommend/as_expression.next.stderr

@@ -29,10 +29,7 @@ error[E0271]: type mismatch resolving `<SelectInt as Expression>::SqlType == Tex
   --> $DIR/as_expression.rs:57:5
    |
 LL |     SelectInt.check("bar");
-   |     ^^^^^^^^^^^^^^^^^^^^^^ expected `Integer`, found `Text`
+   |     ^^^^^^^^^^^^^^^^^^^^^^ expected `Text`, found `Integer`
-   |
-   = note: expected struct `Integer`
-              found struct `Text`
 
 error: aborting due to 3 previous errors
 

tests/ui/impl-trait/bound-normalization-fail.stderr

@@ -7,13 +7,13 @@ LL |
 LL |         Foo(())
    |         ------- return type was inferred to be `Foo<()>` here
    |
-note: expected this to be `()`
+note: expected this to be `<T as impl_trait::Trait>::Assoc`
   --> $DIR/bound-normalization-fail.rs:14:19
    |
 LL |     type Output = T;
    |                   ^
-   = note:    expected unit type `()`
+   = note: expected associated type `<T as impl_trait::Trait>::Assoc`
-           found associated type `<T as impl_trait::Trait>::Assoc`
+                    found unit type `()`
 help: consider constraining the associated type `<T as impl_trait::Trait>::Assoc` to `()`
    |
 LL |     fn foo_fail<T: Trait<Assoc = ()>>() -> impl FooLike<Output = T::Assoc> {
@@ -28,13 +28,13 @@ LL |
 LL |         Foo(())
    |         ------- return type was inferred to be `Foo<()>` here
    |
-note: expected this to be `()`
+note: expected this to be `<T as lifetimes::Trait<'a>>::Assoc`
   --> $DIR/bound-normalization-fail.rs:14:19
    |
 LL |     type Output = T;
    |                   ^
-   = note:    expected unit type `()`
+   = note: expected associated type `<T as lifetimes::Trait<'a>>::Assoc`
-           found associated type `<T as lifetimes::Trait<'a>>::Assoc`
+                    found unit type `()`
 help: consider constraining the associated type `<T as lifetimes::Trait<'a>>::Assoc` to `()`
    |
 LL |     fn foo2_fail<'a, T: Trait<'a, Assoc = ()>>() -> impl FooLike<Output = T::Assoc> {

tests/ui/impl-trait/in-trait/default-body-type-err.stderr

@@ -2,7 +2,7 @@ error[E0271]: type mismatch resolving `<&i32 as Deref>::Target == String`
   --> $DIR/default-body-type-err.rs:4:22
    |
 LL |     fn lol(&self) -> impl Deref<Target = String> {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `String`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `String`, found `i32`
 LL |
 LL |         &1i32
    |         ----- return type was inferred to be `&i32` here

tests/ui/impl-trait/issues/issue-78722-2.stderr

@@ -16,7 +16,7 @@ error[E0271]: expected `{async block@$DIR/issue-78722-2.rs:13:13: 13:18}` to be
   --> $DIR/issue-78722-2.rs:11:30
    |
 LL |         fn concrete_use() -> F {
-   |                              ^ expected `()`, found `u8`
+   |                              ^ expected `u8`, found `()`
 
 error: aborting due to 2 previous errors
 

tests/ui/impl-trait/issues/issue-78722.stderr

@@ -12,7 +12,7 @@ error[E0271]: expected `{async block@$DIR/issue-78722.rs:10:13: 10:18}` to be a
   --> $DIR/issue-78722.rs:8:30
    |
 LL |         fn concrete_use() -> F {
-   |                              ^ expected `()`, found `u8`
+   |                              ^ expected `u8`, found `()`
 
 error: aborting due to 2 previous errors
 

tests/ui/impl-trait/projection-mismatch-in-impl-where-clause.stderr

@@ -4,7 +4,7 @@ error[E0271]: type mismatch resolving `<() as Super>::Assoc == ()`
 LL | fn test() -> impl Test {
    |              ^^^^^^^^^ type mismatch resolving `<() as Super>::Assoc == ()`
    |
-note: expected this to be `u8`
+note: expected this to be `()`
   --> $DIR/projection-mismatch-in-impl-where-clause.rs:6:18
    |
 LL |     type Assoc = u8;

tests/ui/issues/issue-33941.stderr

@@ -20,10 +20,10 @@ error[E0271]: expected `Iter<'_, _, _>` to be an iterator that yields `&_`, but
   --> $DIR/issue-33941.rs:6:14
    |
 LL |     for _ in HashMap::new().iter().cloned() {}
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `(&_, &_)`, found `&_`
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&_`, found `(&_, &_)`
    |
-   = note:  expected tuple `(&_, &_)`
+   = note: expected reference `&_`
-           found reference `&_`
+                  found tuple `(&_, &_)`
    = note: required for `Cloned<std::collections::hash_map::Iter<'_, _, _>>` to implement `Iterator`
    = note: required for `Cloned<std::collections::hash_map::Iter<'_, _, _>>` to implement `IntoIterator`
 

tests/ui/issues/issue-67039-unsound-pin-partialeq.stderr

@@ -2,10 +2,10 @@ error[E0271]: type mismatch resolving `<Rc<Apple> as Deref>::Target == Rc<Apple>
   --> $DIR/issue-67039-unsound-pin-partialeq.rs:25:29
    |
 LL |     let _ = Pin::new(Apple) == Rc::pin(Apple);
-   |                             ^^ expected `Apple`, found `Rc<Apple>`
+   |                             ^^ expected `Rc<Apple>`, found `Apple`
    |
-   = note: expected struct `Apple`
+   = note: expected struct `Rc<Apple>`
-              found struct `Rc<Apple>`
+              found struct `Apple`
    = note: required for `Pin<Apple>` to implement `PartialEq<Pin<Rc<Apple>>>`
 
 error: aborting due to 1 previous error

tests/ui/lint/issue-106991.stderr

@@ -2,7 +2,7 @@ error[E0271]: expected `foo` to be a fn item that returns `i32`, but it returns
   --> $DIR/issue-106991.rs:5:13
    |
 LL | fn bar() -> impl Iterator<Item = i32> {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `i32`
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `()`
    |
    = note: required for `Map<std::slice::IterMut<'_, Vec<u8>>, for<'a> fn(&'a mut Vec<u8>) {foo}>` to implement `Iterator`
 

tests/ui/suggestions/trait-hidden-method.stderr

@@ -8,14 +8,14 @@ error[E0271]: expected `Box<dyn Iterator>` to be an iterator that yields `u32`,
   --> $DIR/trait-hidden-method.rs:3:32
    |
 LL | pub fn i_can_has_iterator() -> impl Iterator<Item = u32> {
-   |                                ^^^^^^^^^^^^^^^^^^^^^^^^^ expected associated type, found `u32`
+   |                                ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found associated type
 ...
 LL |     Box::new(1..=10) as Box<dyn Iterator>
    |     ------------------------------------- return type was inferred to be `Box<dyn Iterator>` here
    |
-   = note: expected associated type `<dyn Iterator as Iterator>::Item`
+   = note:         expected type `u32`
-                         found type `u32`
+           found associated type `<dyn Iterator as Iterator>::Item`
-   = help: consider constraining the associated type `<dyn Iterator as Iterator>::Item` to `u32` or calling a method that returns `<dyn Iterator as Iterator>::Item`
+   = help: consider constraining the associated type `<dyn Iterator as Iterator>::Item` to `u32`
    = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error: aborting due to 2 previous errors

tests/ui/traits/next-solver/async.fail.stderr

@@ -2,12 +2,10 @@ error[E0271]: expected `{async block@$DIR/async.rs:12:17: 12:22}` to be a future
   --> $DIR/async.rs:12:17
    |
 LL |     needs_async(async {});
-   |     ----------- ^^^^^^^^ expected `()`, found `i32`
+   |     ----------- ^^^^^^^^ expected `i32`, found `()`
    |     |
    |     required by a bound introduced by this call
    |
-   = note: expected unit type `()`
-                   found type `i32`
 note: required by a bound in `needs_async`
   --> $DIR/async.rs:8:31
    |

tests/ui/traits/next-solver/more-object-bound.stderr

@@ -2,19 +2,14 @@ error[E0271]: type mismatch resolving `<dyn Trait<A = A, B = B> as SuperTrait>::
   --> $DIR/more-object-bound.rs:12:5
    |
 LL | fn transmute<A, B>(x: A) -> B {
-   |              -  -
+   |              -  - expected type parameter
-   |              |  |
+   |              |
-   |              |  expected type parameter
-   |              |  found type parameter
    |              found type parameter
-   |              expected type parameter
 LL |     foo::<A, B, dyn Trait<A = A, B = B>>(x)
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected type parameter `A`, found type parameter `B`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected type parameter `B`, found type parameter `A`
    |
-   = note: expected type parameter `A`
+   = note: expected type parameter `B`
-              found type parameter `B`
+              found type parameter `A`
-   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
-   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
    = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
    = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
    = note: required because it appears within the type `dyn Trait<A = A, B = B>`

tests/ui/try-block/try-block-bad-type.stderr

@@ -15,13 +15,13 @@ error[E0271]: type mismatch resolving `<Result<i32, i32> as Try>::Output == &str
   --> $DIR/try-block-bad-type.rs:12:9
    |
 LL |         ""
-   |         ^^ expected `i32`, found `&str`
+   |         ^^ expected `&str`, found `i32`
 
 error[E0271]: type mismatch resolving `<Result<i32, i32> as Try>::Output == ()`
   --> $DIR/try-block-bad-type.rs:15:39
    |
 LL |     let res: Result<i32, i32> = try { };
-   |                                       ^ expected `i32`, found `()`
+   |                                       ^ expected `()`, found `i32`
 
 error[E0277]: a `try` block must return `Result` or `Option` (or another type that implements `Try`)
   --> $DIR/try-block-bad-type.rs:17:25

tests/ui/try-block/try-block-type-error.stderr

@@ -2,18 +2,13 @@ error[E0271]: type mismatch resolving `<Option<f32> as Try>::Output == {integer}
   --> $DIR/try-block-type-error.rs:10:9
    |
 LL |         42
-   |         ^^ expected `f32`, found integer
+   |         ^^ expected integer, found `f32`
-   |
-help: use a float literal
-   |
-LL |         42.0
-   |           ++
 
 error[E0271]: type mismatch resolving `<Option<i32> as Try>::Output == ()`
   --> $DIR/try-block-type-error.rs:16:5
    |
 LL |     };
-   |     ^ expected `i32`, found `()`
+   |     ^ expected `()`, found `i32`
 
 error: aborting due to 2 previous errors
 

tests/ui/type-alias-impl-trait/hidden_type_mismatch.stderr

@@ -2,18 +2,18 @@ error[E0271]: type mismatch resolving `<() as Proj>::Assoc == i32`
   --> $DIR/hidden_type_mismatch.rs:43:9
    |
 LL |     pub type Sep = impl Sized + std::fmt::Display;
-   |                    ------------------------------ the expected opaque type
+   |                    ------------------------------ the found opaque type
 ...
 LL |         Bar { inner: 1i32, _marker: () }
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type mismatch resolving `<() as Proj>::Assoc == i32`
    |
-note: expected this to be `Sep`
+note: expected this to be `i32`
   --> $DIR/hidden_type_mismatch.rs:20:22
    |
 LL |         type Assoc = sus::Sep;
    |                      ^^^^^^^^
-   = note: expected opaque type `Sep`
+   = note:     expected type `i32`
-                     found type `i32`
+           found opaque type `Sep`
 note: required for `Bar<()>` to implement `Copy`
   --> $DIR/hidden_type_mismatch.rs:32:39
    |

tests/ui/type-alias-impl-trait/issue-94429.stderr

@@ -2,7 +2,7 @@ error[E0271]: type mismatch resolving `<{coroutine@$DIR/issue-94429.rs:18:9: 18:
   --> $DIR/issue-94429.rs:15:26
    |
 LL |     fn run(&mut self) -> Self::Coro {
-   |                          ^^^^^^^^^^ expected integer, found `()`
+   |                          ^^^^^^^^^^ expected `()`, found integer
 
 error: aborting due to 1 previous error