peel derives when checking normalized is expected

Author: SNCPlay42

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

@@ -1190,7 +1190,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
                 );
 
                 let is_normalized_ty_expected = !matches!(
-                    obligation.cause.code,
+                    obligation.cause.code.peel_derives(),
                     ObligationCauseCode::ItemObligation(_)
                         | ObligationCauseCode::BindingObligation(_, _)
                         | ObligationCauseCode::ObjectCastObligation(_)

src/test/ui/associated-types/issue-44153.stderr

@@ -5,7 +5,7 @@ LL |     fn visit() {}
    |     ---------- required by `Visit::visit`
 ...
 LL |     <() as Visit>::visit();
-   |     ^^^^^^^^^^^^^^^^^^^^ expected `()`, found `&()`
+   |     ^^^^^^^^^^^^^^^^^^^^ expected `&()`, found `()`
    |
    = note: required because of the requirements on the impl of `Visit` for `()`
 

src/test/ui/impl-trait/projection-mismatch-in-impl-where-clause.rs

@@ -0,0 +1,20 @@
+pub trait Super {
+    type Assoc;
+}
+
+impl Super for () {
+    type Assoc = u8;
+}
+
+pub trait Test {}
+
+impl<T> Test for T where T: Super<Assoc = ()> {}
+
+fn test() -> impl Test {
+    //~^ERROR type mismatch resolving `<() as Super>::Assoc == ()`
+    ()
+}
+
+fn main() {
+    let a = test();
+}

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

@@ -0,0 +1,11 @@
+error[E0271]: type mismatch resolving `<() as Super>::Assoc == ()`
+  --> $DIR/projection-mismatch-in-impl-where-clause.rs:13:14
+   |
+LL | fn test() -> impl Test {
+   |              ^^^^^^^^^ expected `()`, found `u8`
+   |
+   = note: required because of the requirements on the impl of `Test` for `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.

src/test/ui/issues/issue-33941.stderr

@@ -11,10 +11,10 @@ error[E0271]: type mismatch resolving `<std::collections::hash_map::Iter<'_, _,
   --> $DIR/issue-33941.rs:4:14
    |
 LL |     for _ in HashMap::new().iter().cloned() {}
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected tuple, found reference
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found tuple
    |
-   = note:  expected tuple `(&_, &_)`
-           found reference `&_`
+   = note: expected reference `&_`
+                  found tuple `(&_, &_)`
    = note: required because of the requirements on the impl of `Iterator` for `Cloned<std::collections::hash_map::Iter<'_, _, _>>`
    = note: required because of the requirements on the impl of `IntoIterator` for `Cloned<std::collections::hash_map::Iter<'_, _, _>>`
    = note: required by `into_iter`
@@ -23,10 +23,10 @@ error[E0271]: type mismatch resolving `<std::collections::hash_map::Iter<'_, _,
   --> $DIR/issue-33941.rs:4:14
    |
 LL |     for _ in HashMap::new().iter().cloned() {}
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected tuple, found reference
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found tuple
    |
-   = note:  expected tuple `(&_, &_)`
-           found reference `&_`
+   = note: expected reference `&_`
+                  found tuple `(&_, &_)`
    = note: required because of the requirements on the impl of `Iterator` for `Cloned<std::collections::hash_map::Iter<'_, _, _>>`
    = note: required by `std::iter::Iterator::next`
 

src/test/ui/issues/issue-39970.stderr

@@ -5,7 +5,7 @@ LL |     fn visit() {}
    |     ---------- required by `Visit::visit`
 ...
 LL |     <() as Visit>::visit();
-   |     ^^^^^^^^^^^^^^^^^^^^ expected `&()`, found `()`
+   |     ^^^^^^^^^^^^^^^^^^^^ expected `()`, found `&()`
    |
    = note: required because of the requirements on the impl of `Visit` for `()`