Work around the fact that check_mod_type_wf may spuriously return ErrorGuaranteed, even if that error is only emitted by check_modwitem_types

Author: oli-obk

compiler/rustc_hir_analysis/src/check/check.rs

@@ -128,7 +128,11 @@ fn check_union_fields(tcx: TyCtxt<'_>, span: Span, item_def_id: LocalDefId) -> b
 
         let param_env = tcx.param_env(item_def_id);
         for field in &def.non_enum_variant().fields {
-            let field_ty = tcx.normalize_erasing_regions(param_env, field.ty(tcx, args));
+            let Ok(field_ty) = tcx.try_normalize_erasing_regions(param_env, field.ty(tcx, args))
+            else {
+                tcx.sess.delay_span_bug(span, "could not normalize field type");
+                continue;
+            };
 
             if !allowed_union_field(field_ty, tcx, param_env) {
                 let (field_span, ty_span) = match tcx.hir().get_if_local(field.did) {

compiler/rustc_hir_analysis/src/lib.rs

@@ -205,15 +205,19 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
         })?;
     }
 
-    tcx.sess.time("wf_checking", || {
+    let errs = tcx.sess.time("wf_checking", || {
         tcx.hir().try_par_for_each_module(|module| tcx.ensure().check_mod_type_wf(module))
-    })?;
+    });
 
     // NOTE: This is copy/pasted in librustdoc/core.rs and should be kept in sync.
     tcx.sess.time("item_types_checking", || {
         tcx.hir().for_each_module(|module| tcx.ensure().check_mod_item_types(module))
     });
 
+    // HACK: `check_mod_type_wf` may spuriously emit errors due to `delay_span_bug`, even if those errors
+    // only actually get emitted in `check_mod_item_types`.
+    errs?;
+
     if tcx.features().rustc_attrs {
         tcx.sess.track_errors(|| collect::test_opaque_hidden_types(tcx))?;
     }