Allow const eval failures if the cause is a type layout issue

2 files changed, 19 insertions, 7 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/error.rs b/compiler/rustc_const_eval/src/const_eval/error.rs
index 08c9609eacf..7a1c2a7b6fa 100644
--- a/compiler/rustc_const_eval/src/const_eval/error.rs
+++ b/compiler/rustc_const_eval/src/const_eval/error.rs
@@ -2,7 +2,7 @@ use std::mem;
 
 use rustc_errors::{DiagArgName, DiagArgValue, DiagMessage, Diagnostic, IntoDiagArg};
 use rustc_hir::CRATE_HIR_ID;
-use rustc_middle::mir::interpret::Provenance;
+use rustc_middle::mir::interpret::{Provenance, ReportedErrorInfo};
 use rustc_middle::mir::AssertKind;
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::ty::TyCtxt;
@@ -139,9 +139,10 @@ where
             ErrorHandled::TooGeneric(span)
         }
         err_inval!(AlreadyReported(guar)) => ErrorHandled::Reported(guar, span),
-        err_inval!(Layout(LayoutError::ReferencesError(guar))) => {
-            ErrorHandled::Reported(guar.into(), span)
-        }
+        err_inval!(Layout(LayoutError::ReferencesError(guar))) => ErrorHandled::Reported(
+            ReportedErrorInfo::tainted_by_errors(guar),
+            span,
+        ),
         // Report remaining errors.
         _ => {
             let (our_span, frames) = get_span_and_frames();
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 344bb7cd98b..1207150b8b1 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -1181,9 +1181,20 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
         M::eval_mir_constant(self, *val, span, layout, |ecx, val, span, layout| {
             let const_val = val.eval(*ecx.tcx, ecx.param_env, span).map_err(|err| {
-                if M::ALL_CONSTS_ARE_PRECHECKED && !matches!(err, ErrorHandled::TooGeneric(..)) {
-                    // Looks like the const is not captued by `required_consts`, that's bad.
-                    bug!("interpret const eval failure of {val:?} which is not in required_consts");
+                if M::ALL_CONSTS_ARE_PRECHECKED {
+                    match err {
+                        ErrorHandled::TooGeneric(..) => {},
+                        ErrorHandled::Reported(reported, span) => {
+                            if reported.is_tainted_by_errors() {
+                                // const-eval will return "tainted" errors if e.g. the layout cannot
+                                // be computed as the type references non-existing names.
+                                // See <https://github.com/rust-lang/rust/issues/124348>.
+                            } else {
+                                // Looks like the const is not captued by `required_consts`, that's bad.
+                                span_bug!(span, "interpret const eval failure of {val:?} which is not in required_consts");
+                            }
+                        }
+                    }
                 }
                 err.emit_note(*ecx.tcx);
                 err