Auto merge of #77306 - lcnr:inline-ok, r=eddyb

normalize substs while inlining

fixes #68347 or more precisely, this fixes the same ICE in rust analyser as veloren is pinned to a specific nightly
and had an error with the current one.

I didn't look into creating an MVCE here as that seems fairly annoying, will spend a few minutes doing so rn. (failed)

r? `@eddyb` cc `@bjorn3`

1 files changed, 7 insertions, 4 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/codegen/mod.rs b/compiler/rustc_trait_selection/src/traits/codegen/mod.rs
index dd7ea55cc10..05e6c4804ff 100644
--- a/compiler/rustc_trait_selection/src/traits/codegen/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/codegen/mod.rs
@@ -17,14 +17,17 @@ use rustc_middle::ty::{self, TyCtxt};
 /// (necessarily) resolve all nested obligations on the impl. Note
 /// that type check should guarantee to us that all nested
 /// obligations *could be* resolved if we wanted to.
+///
 /// Assumes that this is run after the entire crate has been successfully type-checked.
+/// This also expects that `trait_ref` is fully normalized.
 pub fn codegen_fulfill_obligation<'tcx>(
-    ty: TyCtxt<'tcx>,
+    tcx: TyCtxt<'tcx>,
     (param_env, trait_ref): (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>),
 ) -> Result<ImplSource<'tcx, ()>, ErrorReported> {
     // Remove any references to regions; this helps improve caching.
-    let trait_ref = ty.erase_regions(&trait_ref);
-
+    let trait_ref = tcx.erase_regions(&trait_ref);
+    // We expect the input to be fully normalized.
+    debug_assert_eq!(trait_ref, tcx.normalize_erasing_regions(param_env, trait_ref));
     debug!(
         "codegen_fulfill_obligation(trait_ref={:?}, def_id={:?})",
         (param_env, trait_ref),
@@ -33,7 +36,7 @@ pub fn codegen_fulfill_obligation<'tcx>(
 
     // Do the initial selection for the obligation. This yields the
     // shallow result we are looking for -- that is, what specific impl.
-    ty.infer_ctxt().enter(|infcx| {
+    tcx.infer_ctxt().enter(|infcx| {
         let mut selcx = SelectionContext::new(&infcx);
 
         let obligation_cause = ObligationCause::dummy();