Rollup merge of #119818 - oli-obk:even_more_follow_up_errors3, r=compiler-errors

Silence some follow-up errors [3/x]

this is one piece of the requested cleanups from https://github.com/rust-lang/rust/pull/117449

Keep error types around, even in obligations.

These help silence follow-up errors, as we now figure out that some types (most notably inference variables) are equal to an error type.

But it also allows figuring out more types in the presence of errors, possibly causing more errors.

9 files changed, 22 insertions, 55 deletions

diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index 11b5b437eff..db46b39ce25 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -631,13 +631,6 @@ impl<'tcx> InferCtxt<'tcx> {
                 ct_op: |ct| ct,
             });
 
-            if let ty::ClauseKind::Projection(projection) = predicate.kind().skip_binder() {
-                if projection.term.references_error() {
-                    // No point on adding any obligations since there's a type error involved.
-                    obligations.clear();
-                    return;
-                }
-            }
             // Require that the predicate holds for the concrete type.
             debug!(?predicate);
             obligations.push(traits::Obligation::new(
diff --git a/tests/ui/async-await/issues/issue-65159.rs b/tests/ui/async-await/issues/issue-65159.rs
index aed111e2144..7197a4fb91a 100644
--- a/tests/ui/async-await/issues/issue-65159.rs
+++ b/tests/ui/async-await/issues/issue-65159.rs
@@ -5,7 +5,7 @@
 async fn copy() -> Result<()>
 //~^ ERROR enum takes 2 generic arguments
 {
-    Ok(()) //~ ERROR: type annotations needed
+    Ok(())
 }
 
-fn main() { }
+fn main() {}
diff --git a/tests/ui/async-await/issues/issue-65159.stderr b/tests/ui/async-await/issues/issue-65159.stderr
index 77a0ea5027c..19512116a66 100644
--- a/tests/ui/async-await/issues/issue-65159.stderr
+++ b/tests/ui/async-await/issues/issue-65159.stderr
@@ -11,18 +11,6 @@ help: add missing generic argument
 LL | async fn copy() -> Result<(), E>
    |                             +++
 
-error[E0282]: type annotations needed
-  --> $DIR/issue-65159.rs:8:5
-   |
-LL |     Ok(())
-   |     ^^ cannot infer type of the type parameter `E` declared on the enum `Result`
-   |
-help: consider specifying the generic arguments
-   |
-LL |     Ok::<(), E>(())
-   |       +++++++++
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 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`.
diff --git a/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.rs b/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.rs
index c10246eec64..b52939ffc11 100644
--- a/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.rs
+++ b/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.rs
@@ -17,7 +17,6 @@ async fn buy_lock(coroutine: &Mutex<MarketMultiplier>) -> LockedMarket<'_> {
     //~^ ERROR struct takes 0 lifetime arguments but 1 lifetime argument was supplied
     //~^^ ERROR struct takes 1 generic argument but 0 generic arguments were supplied
     LockedMarket(coroutine.lock().unwrap().buy())
-    //~^ ERROR: cannot return value referencing temporary value
 }
 
 struct LockedMarket<T>(T);
diff --git a/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.stderr b/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.stderr
index 2b10cf67d15..516c1d065e6 100644
--- a/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.stderr
+++ b/tests/ui/borrowck/issue-82126-mismatched-subst-and-hir.stderr
@@ -7,7 +7,7 @@ LL | async fn buy_lock(coroutine: &Mutex<MarketMultiplier>) -> LockedMarket<'_>
    |                                                           expected 0 lifetime arguments
    |
 note: struct defined here, with 0 lifetime parameters
-  --> $DIR/issue-82126-mismatched-subst-and-hir.rs:23:8
+  --> $DIR/issue-82126-mismatched-subst-and-hir.rs:22:8
    |
 LL | struct LockedMarket<T>(T);
    |        ^^^^^^^^^^^^
@@ -19,7 +19,7 @@ LL | async fn buy_lock(coroutine: &Mutex<MarketMultiplier>) -> LockedMarket<'_>
    |                                                           ^^^^^^^^^^^^ expected 1 generic argument
    |
 note: struct defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-82126-mismatched-subst-and-hir.rs:23:8
+  --> $DIR/issue-82126-mismatched-subst-and-hir.rs:22:8
    |
 LL | struct LockedMarket<T>(T);
    |        ^^^^^^^^^^^^ -
@@ -28,16 +28,6 @@ help: add missing generic argument
 LL | async fn buy_lock(coroutine: &Mutex<MarketMultiplier>) -> LockedMarket<'_, T> {
    |                                                                          +++
 
-error[E0515]: cannot return value referencing temporary value
-  --> $DIR/issue-82126-mismatched-subst-and-hir.rs:19:5
-   |
-LL |     LockedMarket(coroutine.lock().unwrap().buy())
-   |     ^^^^^^^^^^^^^-------------------------^^^^^^^
-   |     |            |
-   |     |            temporary value created here
-   |     returns a value referencing data owned by the current function
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0107, E0515.
-For more information about an error, try `rustc --explain E0107`.
+For more information about this error, try `rustc --explain E0107`.
diff --git a/tests/ui/impl-trait/issue-72911.rs b/tests/ui/impl-trait/issue-72911.rs
index 63f4898f430..7ba8579e24f 100644
--- a/tests/ui/impl-trait/issue-72911.rs
+++ b/tests/ui/impl-trait/issue-72911.rs
@@ -15,6 +15,7 @@ fn gather_from_file(dir_entry: &foo::MissingItem) -> impl Iterator<Item = Lint>
 
 fn lint_files() -> impl Iterator<Item = foo::MissingItem> {
     //~^ ERROR: failed to resolve
+    //~| ERROR: `()` is not an iterator
     unimplemented!()
 }
 
diff --git a/tests/ui/impl-trait/issue-72911.stderr b/tests/ui/impl-trait/issue-72911.stderr
index 0e86561aa27..44c20a7be53 100644
--- a/tests/ui/impl-trait/issue-72911.stderr
+++ b/tests/ui/impl-trait/issue-72911.stderr
@@ -1,3 +1,11 @@
+error[E0277]: `()` is not an iterator
+  --> $DIR/issue-72911.rs:16:20
+   |
+LL | fn lint_files() -> impl Iterator<Item = foo::MissingItem> {
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `()` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `()`
+
 error[E0433]: failed to resolve: use of undeclared crate or module `foo`
   --> $DIR/issue-72911.rs:11:33
    |
@@ -10,6 +18,7 @@ error[E0433]: failed to resolve: use of undeclared crate or module `foo`
 LL | fn lint_files() -> impl Iterator<Item = foo::MissingItem> {
    |                                         ^^^ use of undeclared crate or module `foo`
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0433`.
+Some errors have detailed explanations: E0277, E0433.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/impl-trait/issues/issue-92305.rs b/tests/ui/impl-trait/issues/issue-92305.rs
index e16199caaaa..4a89238d07e 100644
--- a/tests/ui/impl-trait/issues/issue-92305.rs
+++ b/tests/ui/impl-trait/issues/issue-92305.rs
@@ -5,7 +5,6 @@ use std::iter;
 fn f<T>(data: &[T]) -> impl Iterator<Item = Vec> {
     //~^ ERROR: missing generics for struct `Vec` [E0107]
     iter::empty()
-    //~^ ERROR: type annotations needed
 }
 
 fn g<T>(data: &[T], target: T) -> impl Iterator<Item = Vec<T>> {
diff --git a/tests/ui/impl-trait/issues/issue-92305.stderr b/tests/ui/impl-trait/issues/issue-92305.stderr
index 55e966bd7bf..88fb1fb2707 100644
--- a/tests/ui/impl-trait/issues/issue-92305.stderr
+++ b/tests/ui/impl-trait/issues/issue-92305.stderr
@@ -9,18 +9,6 @@ help: add missing generic argument
 LL | fn f<T>(data: &[T]) -> impl Iterator<Item = Vec<T>> {
    |                                                +++
 
-error[E0282]: type annotations needed
-  --> $DIR/issue-92305.rs:7:5
-   |
-LL |     iter::empty()
-   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
-   |
-help: consider specifying the generic argument
-   |
-LL |     iter::empty::<T>()
-   |                +++++
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 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`.