Auto merge of #93691 - compiler-errors:mir-tainted-by-errors, r=oli-obk

Implement `tainted_by_errors` in MIR borrowck, use it to skip CTFE

Putting this up for initial review. The issue that I found is when we're evaluating a const, we're doing borrowck, but doing nothing with the fact that borrowck fails.

This implements a `tainted_by_errors` field for MIR borrowck like we have in infcx, so we can use that information to return an `Err` during const eval if our const fails to borrowck.

This PR needs some cleaning up. I should probably just use `Result` in more places, instead of `.expect`ing in the places I am, but I just wanted it to compile so I could see if it worked!

Fixes #93646

r? `@oli-obk`
feel free to reassign

3 files changed, 8 insertions, 5 deletions

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index 6799514a449..12a8b8c6d77 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -120,7 +120,7 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
     fn in_return_place(
         &mut self,
         ccx: &'mir ConstCx<'mir, 'tcx>,
-        error_occured: Option<ErrorReported>,
+        tainted_by_errors: Option<ErrorReported>,
     ) -> ConstQualifs {
         // Find the `Return` terminator if one exists.
         //
@@ -134,7 +134,9 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
             .map(|(bb, _)| bb);
 
         let return_block = match return_block {
-            None => return qualifs::in_any_value_of_ty(ccx, ccx.body.return_ty(), error_occured),
+            None => {
+                return qualifs::in_any_value_of_ty(ccx, ccx.body.return_ty(), tainted_by_errors);
+            }
             Some(bb) => bb,
         };
 
@@ -166,7 +168,7 @@ impl<'mir, 'tcx> Qualifs<'mir, 'tcx> {
             needs_non_const_drop: self.needs_non_const_drop(ccx, RETURN_PLACE, return_loc),
             has_mut_interior: self.has_mut_interior(ccx, RETURN_PLACE, return_loc),
             custom_eq,
-            error_occured,
+            tainted_by_errors,
         }
     }
 }
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
index 91610b15eb9..c3fa98b000f 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
@@ -17,14 +17,14 @@ use super::ConstCx;
 pub fn in_any_value_of_ty<'tcx>(
     cx: &ConstCx<'_, 'tcx>,
     ty: Ty<'tcx>,
-    error_occured: Option<ErrorReported>,
+    tainted_by_errors: Option<ErrorReported>,
 ) -> ConstQualifs {
     ConstQualifs {
         has_mut_interior: HasMutInterior::in_any_value_of_ty(cx, ty),
         needs_drop: NeedsDrop::in_any_value_of_ty(cx, ty),
         needs_non_const_drop: NeedsNonConstDrop::in_any_value_of_ty(cx, ty),
         custom_eq: CustomEq::in_any_value_of_ty(cx, ty),
-        error_occured,
+        tainted_by_errors,
     }
 }
 
diff --git a/compiler/rustc_const_eval/src/transform/promote_consts.rs b/compiler/rustc_const_eval/src/transform/promote_consts.rs
index ac282a5ecc8..92d1f5bceef 100644
--- a/compiler/rustc_const_eval/src/transform/promote_consts.rs
+++ b/compiler/rustc_const_eval/src/transform/promote_consts.rs
@@ -974,6 +974,7 @@ pub fn promote_candidates<'tcx>(
             vec![],
             body.span,
             body.generator_kind(),
+            body.tainted_by_errors,
         );
 
         let promoter = Promoter {