Rollup merge of rust-lang#134742 - compiler-errors:post-borrowck-analysis, r=lcnr

Use `PostBorrowckAnalysis` in `check_coroutine_obligations`

This currently errors with:

```
error: concrete type differs from previous defining opaque type use
  --> tests/ui/coroutine/issue-52304.rs:10:21
   |
10 | pub fn example() -> impl Coroutine {
   |                     ^^^^^^^^^^^^^^ expected `{example::{closure#0} upvar_tys=() resume_ty=() yield_ty=&'{erased} i32 return_ty=() witness={example::{closure#0}}}`, got `{example::{closure#0} upvar_tys=() resume_ty=() yield_ty=&'static i32 return_ty=() witness={example::{closure#0}}}`
   |
   = note: previous use here
```

This is because we end up redefining the opaque in `check_coroutine_obligations` but with the `yield_ty = &'erased i32` from hir typeck, which causes the *equality* check for opaques to fail.

The coroutine obligtions in question (when `-Znext-solver` is enabled) are:

```
Binder { value: TraitPredicate(<Opaque(DefId(0:5 ~ issue_52304[4c6d]::example::{opaque#0}), []) as std::marker::Sized>, polarity:Positive), bound_vars: [] }

Binder { value: AliasRelate(Term::Ty(Alias(Opaque, AliasTy { args: [], def_id: DefId(0:5 ~ issue_52304[4c6d]::example::{opaque#0}), .. })), Equate, Term::Ty(Coroutine(DefId(0:6 ~ issue_52304[4c6d]::example::{closure#0}), [(), (), &'{erased} i32, (), CoroutineWitness(DefId(0:6 ~ issue_52304[4c6d]::example::{closure#0}), []), ()]))), bound_vars: [] }

Binder { value: AliasRelate(Term::Ty(Coroutine(DefId(0:6 ~ issue_52304[4c6d]::example::{closure#0}), [(), (), &'{erased} i32, (), CoroutineWitness(DefId(0:6 ~ issue_52304[4c6d]::example::{closure#0}), []), ()])), Subtype, Term::Ty(Alias(Opaque, AliasTy { args: [], def_id: DefId(0:5 ~ issue_52304[4c6d]::example::{opaque#0}), .. }))), bound_vars: [] }
```

Ignoring the fact that we end up stalling some really dumb obligations here (lol), I think it makes more sense for us to be using post borrowck analysis for this check anyways.

r? lcnr

Author: matthiaskrgr

compiler/rustc_hir_analysis/src/check/check.rs

@@ -1845,13 +1845,18 @@ pub(super) fn check_coroutine_obligations(
 
     debug!(?typeck_results.coroutine_stalled_predicates);
 
+    let mode = if tcx.next_trait_solver_globally() {
+        TypingMode::post_borrowck_analysis(tcx, def_id)
+    } else {
+        TypingMode::analysis_in_body(tcx, def_id)
+    };
+
     let infcx = tcx
         .infer_ctxt()
         // typeck writeback gives us predicates with their regions erased.
         // As borrowck already has checked lifetimes, we do not need to do it again.
         .ignoring_regions()
-        // FIXME(#132279): This should eventually use the already defined hidden types.
-        .build(TypingMode::analysis_in_body(tcx, def_id));
+        .build(mode);
 
     let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
     for (predicate, cause) in &typeck_results.coroutine_stalled_predicates {
@@ -1864,12 +1869,14 @@ pub(super) fn check_coroutine_obligations(
         return Err(infcx.err_ctxt().report_fulfillment_errors(errors));
     }
 
-    // Check that any hidden types found when checking these stalled coroutine obligations
-    // are valid.
-    for (key, ty) in infcx.take_opaque_types() {
-        let hidden_type = infcx.resolve_vars_if_possible(ty.hidden_type);
-        let key = infcx.resolve_vars_if_possible(key);
-        sanity_check_found_hidden_type(tcx, key, hidden_type)?;
+    if !tcx.next_trait_solver_globally() {
+        // Check that any hidden types found when checking these stalled coroutine obligations
+        // are valid.
+        for (key, ty) in infcx.take_opaque_types() {
+            let hidden_type = infcx.resolve_vars_if_possible(ty.hidden_type);
+            let key = infcx.resolve_vars_if_possible(key);
+            sanity_check_found_hidden_type(tcx, key, hidden_type)?;
+        }
     }
 
     Ok(())

tests/ui/coroutine/issue-52304.rs

@@ -1,4 +1,6 @@
 //@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
 
 #![feature(coroutines, coroutine_trait)]