Auto merge of #103509 - compiler-errors:opaques-w-bound-vars-r-hard, r=oli-obk

Revert "Normalize opaques with escaping bound vars"

This caused a perf regression in #103423, cc `@skyzh` this should fix #103423.

reverts #100980

r? `@oli-obk`

Author: bors

compiler/rustc_trait_selection/src/traits/project.rs

@@ -508,7 +508,7 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
             // This is really important. While we *can* handle this, this has
             // severe performance implications for large opaque types with
             // late-bound regions. See `issue-88862` benchmark.
-            ty::Opaque(def_id, substs) => {
+            ty::Opaque(def_id, substs) if !substs.has_escaping_bound_vars() => {
                 // Only normalize `impl Trait` outside of type inference, usually in codegen.
                 match self.param_env.reveal() {
                     Reveal::UserFacing => ty.super_fold_with(self),

compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -198,7 +198,7 @@ impl<'cx, 'tcx> FallibleTypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
             // This is really important. While we *can* handle this, this has
             // severe performance implications for large opaque types with
             // late-bound regions. See `issue-88862` benchmark.
-            ty::Opaque(def_id, substs) => {
+            ty::Opaque(def_id, substs) if !substs.has_escaping_bound_vars() => {
                 // Only normalize `impl Trait` outside of type inference, usually in codegen.
                 match self.param_env.reveal() {
                     Reveal::UserFacing => ty.try_super_fold_with(self),

src/test/ui/impl-trait/normalize-tait-in-const.rs

@@ -0,0 +1,39 @@
+// known-bug: #103507
+// failure-status: 101
+// normalize-stderr-test "note: .*\n\n" -> ""
+// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
+// rustc-env:RUST_BACKTRACE=0
+
+#![feature(type_alias_impl_trait)]
+#![feature(const_trait_impl)]
+#![feature(const_refs_to_cell)]
+#![feature(inline_const)]
+
+use std::marker::Destruct;
+
+trait T {
+    type Item;
+}
+
+type Alias<'a> = impl T<Item = &'a ()>;
+
+struct S;
+impl<'a> T for &'a S {
+    type Item = &'a ();
+}
+
+const fn filter_positive<'a>() -> &'a Alias<'a> {
+    &&S
+}
+
+const fn with_positive<F: ~const for<'a> Fn(&'a Alias<'a>) + ~const Destruct>(fun: F) {
+    fun(filter_positive());
+}
+
+const fn foo(_: &Alias<'_>) {}
+
+const BAR: () = {
+    with_positive(foo);
+};
+
+fn main() {}

src/test/ui/impl-trait/normalize-tait-in-const.stderr

@@ -0,0 +1,8 @@
+error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:198:90: Failed to normalize <for<'a, 'b> fn(&'a Alias<'b>) {foo} as std::ops::FnOnce<(&&S,)>>::Output, maybe try to call `try_normalize_erasing_regions` instead
+
+query stack during panic:
+#0 [eval_to_allocation_raw] const-evaluating + checking `BAR`
+#1 [eval_to_const_value_raw] simplifying constant for the type system `BAR`
+end of query stack
+error: aborting due to previous error
+