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

19 files changed, 48 insertions, 82 deletions

diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index 5076152dbff..44373ca4866 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/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)| {
-                    infer::ValuePairs::Terms(ExpectedFound::new(
-                        is_normalized_ty_expected,
-                        normalized_ty,
-                        expected_ty,
-                    ))
+                values.map(|(_, _, normalized_ty, expected_ty)| {
+                    infer::ValuePairs::Terms(ExpectedFound::new(true, expected_ty, normalized_ty))
                 }),
                 err,
                 false,
diff --git a/tests/ui/associated-types/impl-trait-return-missing-constraint.stderr b/tests/ui/associated-types/impl-trait-return-missing-constraint.stderr
index 24409b32ad3..2c6c8ee5d19 100644
--- a/tests/ui/associated-types/impl-trait-return-missing-constraint.stderr
+++ b/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`
   --> $DIR/impl-trait-return-missing-constraint.rs:25:13
    |
 LL | fn bar() -> impl Bar {
-   |             -------- the expected opaque type
+   |             -------- the found opaque type
 ...
 LL | fn baz() -> impl Bar<Item = i32> {
-   |             ^^^^^^^^^^^^^^^^^^^^ expected associated type, found `i32`
+   |             ^^^^^^^^^^^^^^^^^^^^ expected `i32`, found associated type
 LL |
 LL |     bar()
    |     ----- return type was inferred to be `impl Bar` here
    |
-   = note: expected associated type `<impl Bar as Foo>::Item`
-                         found type `i32`
-   = help: consider constraining the associated type `<impl Bar as Foo>::Item` to `i32` or calling a method that returns `<impl Bar as Foo>::Item`
-   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
+   = note:         expected type `i32`
+           found associated type `<impl Bar as Foo>::Item`
 help: consider constraining the associated type `<impl Bar as Foo>::Item` to `i32`
    |
 LL | fn bar() -> impl Bar<Item = i32> {
diff --git a/tests/ui/coroutine/type-mismatch-signature-deduction.stderr b/tests/ui/coroutine/type-mismatch-signature-deduction.stderr
index 08927196037..64dc3a8b1f8 100644
--- a/tests/ui/coroutine/type-mismatch-signature-deduction.stderr
+++ b/tests/ui/coroutine/type-mismatch-signature-deduction.stderr
@@ -22,10 +22,10 @@ error[E0271]: type mismatch resolving `<{coroutine@$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}, _>`
-              found type `i32`
+   = note: expected type `i32`
+              found enum `Result<{integer}, _>`
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.next.stderr b/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.next.stderr
index a686b913c55..8c01b61191e 100644
--- a/tests/ui/diagnostic_namespace/do_not_recommend/as_expression.next.stderr
+++ b/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`
-   |
-   = note: expected struct `Integer`
-              found struct `Text`
+   |     ^^^^^^^^^^^^^^^^^^^^^^ expected `Text`, found `Integer`
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/impl-trait/bound-normalization-fail.stderr b/tests/ui/impl-trait/bound-normalization-fail.stderr
index fcac9ac34db..fc124bd1171 100644
--- a/tests/ui/impl-trait/bound-normalization-fail.stderr
+++ b/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 `()`
-           found associated type `<T as impl_trait::Trait>::Assoc`
+   = note: expected 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 `()`
-           found associated type `<T as lifetimes::Trait<'a>>::Assoc`
+   = note: expected 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> {
diff --git a/tests/ui/impl-trait/in-trait/default-body-type-err.stderr b/tests/ui/impl-trait/in-trait/default-body-type-err.stderr
index 6f1ac4bce43..3c737f095ce 100644
--- a/tests/ui/impl-trait/in-trait/default-body-type-err.stderr
+++ b/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`
   --> $DIR/default-body-type-err.rs:4:22
    |
 LL |     fn lol(&self) -> impl Deref<Target = String> {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `String`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `String`, found `i32`
 LL |
 LL |         &1i32
    |         ----- return type was inferred to be `&i32` here
diff --git a/tests/ui/impl-trait/issues/issue-78722-2.stderr b/tests/ui/impl-trait/issues/issue-78722-2.stderr
index 2cf6b94dd9d..27b4b712830 100644
--- a/tests/ui/impl-trait/issues/issue-78722-2.stderr
+++ b/tests/ui/impl-trait/issues/issue-78722-2.stderr
@@ -16,7 +16,7 @@ error[E0271]: expected `{async block@$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
 
diff --git a/tests/ui/impl-trait/issues/issue-78722.stderr b/tests/ui/impl-trait/issues/issue-78722.stderr
index 3642000597f..109bda0c5cd 100644
--- a/tests/ui/impl-trait/issues/issue-78722.stderr
+++ b/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
 
diff --git a/tests/ui/impl-trait/projection-mismatch-in-impl-where-clause.stderr b/tests/ui/impl-trait/projection-mismatch-in-impl-where-clause.stderr
index c4ea4474066..fa71adc6380 100644
--- a/tests/ui/impl-trait/projection-mismatch-in-impl-where-clause.stderr
+++ b/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;
diff --git a/tests/ui/issues/issue-33941.stderr b/tests/ui/issues/issue-33941.stderr
index f1b6b6ba17e..9535ea57430 100644
--- a/tests/ui/issues/issue-33941.stderr
+++ b/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 `(&_, &_)`
-           found reference `&_`
+   = note: expected 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`
 
diff --git a/tests/ui/issues/issue-67039-unsound-pin-partialeq.stderr b/tests/ui/issues/issue-67039-unsound-pin-partialeq.stderr
index 1ea2d48b474..9164e4696eb 100644
--- a/tests/ui/issues/issue-67039-unsound-pin-partialeq.stderr
+++ b/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`
-              found struct `Rc<Apple>`
+   = note: expected struct `Rc<Apple>`
+              found struct `Apple`
    = note: required for `Pin<Apple>` to implement `PartialEq<Pin<Rc<Apple>>>`
 
 error: aborting due to 1 previous error
diff --git a/tests/ui/lint/issue-106991.stderr b/tests/ui/lint/issue-106991.stderr
index 4704e9ef835..9b4fab68102 100644
--- a/tests/ui/lint/issue-106991.stderr
+++ b/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`
 
diff --git a/tests/ui/suggestions/trait-hidden-method.stderr b/tests/ui/suggestions/trait-hidden-method.stderr
index 5dec2071846..729523cde55 100644
--- a/tests/ui/suggestions/trait-hidden-method.stderr
+++ b/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`
-                         found type `u32`
-   = help: consider constraining the associated type `<dyn Iterator as Iterator>::Item` to `u32` or calling a method that returns `<dyn Iterator as Iterator>::Item`
+   = note:         expected type `u32`
+           found associated type `<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
diff --git a/tests/ui/traits/next-solver/async.fail.stderr b/tests/ui/traits/next-solver/async.fail.stderr
index e47da338736..bc89842d16a 100644
--- a/tests/ui/traits/next-solver/async.fail.stderr
+++ b/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
    |
diff --git a/tests/ui/traits/next-solver/more-object-bound.stderr b/tests/ui/traits/next-solver/more-object-bound.stderr
index 043cbdff9ab..39849d4c865 100644
--- a/tests/ui/traits/next-solver/more-object-bound.stderr
+++ b/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
-   |              |  found type parameter
+   |              -  - expected 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`
-              found type parameter `B`
-   = 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: expected 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: required because it appears within the type `dyn Trait<A = A, B = B>`
diff --git a/tests/ui/try-block/try-block-bad-type.stderr b/tests/ui/try-block/try-block-bad-type.stderr
index 6c41b42dc64..e9e6255cd2a 100644
--- a/tests/ui/try-block/try-block-bad-type.stderr
+++ 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
diff --git a/tests/ui/try-block/try-block-type-error.stderr b/tests/ui/try-block/try-block-type-error.stderr
index 2cdb5fdee79..07b1209de9d 100644
--- a/tests/ui/try-block/try-block-type-error.stderr
+++ b/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
-   |
-help: use a float literal
-   |
-LL |         42.0
-   |           ++
+   |         ^^ expected integer, found `f32`
 
 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
 
diff --git a/tests/ui/type-alias-impl-trait/hidden_type_mismatch.stderr b/tests/ui/type-alias-impl-trait/hidden_type_mismatch.stderr
index 21d9ed93366..b05121a489e 100644
--- a/tests/ui/type-alias-impl-trait/hidden_type_mismatch.stderr
+++ b/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`
-                     found type `i32`
+   = note:     expected type `i32`
+           found opaque type `Sep`
 note: required for `Bar<()>` to implement `Copy`
   --> $DIR/hidden_type_mismatch.rs:32:39
    |
diff --git a/tests/ui/type-alias-impl-trait/issue-94429.stderr b/tests/ui/type-alias-impl-trait/issue-94429.stderr
index 4c2020becbe..f41b781f963 100644
--- a/tests/ui/type-alias-impl-trait/issue-94429.stderr
+++ b/tests/ui/type-alias-impl-trait/issue-94429.stderr
@@ -2,7 +2,7 @@ error[E0271]: type mismatch resolving `<{coroutine@$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