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Rollup merge of #108883 - compiler-errors:post-norm-copy-err, r=BoxyUwU

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Suppress copy impl error when post-normalized type references errors

Suppress spurious errors from the `Copy` impl validity check when fields have bad types *post*-normalization, instead of just pre-normalization.

----

The const-generics test regressed recently due to #107965, cc `````@BoxyUwU.`````
 * I think it's because `[_; 0u32]: Copy` now fails to hold because a nested obligation `ConstArgHasType(0u32, usize)` fails.
 * It's interesting that `[const_error]` shows up in the type only after normalization, though, but I'm pretty sure that it's due to the evaluate call that happens when normalizing unevaluated consts.
This commit is contained in:
Matthias Krüger 2023-03-08 21:24:51 +01:00 • committed by GitHub
commit f6b8a9f6db
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7
compiler/rustc_trait_selection/src/traits/misc.rs
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@ -87,7 +87,12 @@ pub fn type_allowed_to_implement_copy<'tcx>(
};
let ty = ocx.normalize(&normalization_cause, param_env, unnormalized_ty);
let normalization_errors = ocx.select_where_possible();
if !normalization_errors.is_empty() {
// NOTE: The post-normalization type may also reference errors,
// such as when we project to a missing type or we have a mismatch
// between expected and found const-generic types. Don't report an
// additional copy error here, since it's not typically useful.
if !normalization_errors.is_empty() || ty.references_error() {
tcx.sess.delay_span_bug(field_span, format!("couldn't normalize struct field `{unnormalized_ty}` when checking Copy implementation"));
continue;
}