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Fix ICE with unsized type in const pattern

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This commit is contained in:
Fabian Wolff 2021-07-11 19:16:26 +02:00
parent 81053b912f
commit 79f0743b6f
3 changed files with 65 additions and 11 deletions
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34
compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
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@ -490,17 +490,29 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
// convert the dereferenced constant to a pattern that is the sub-pattern of the
// deref pattern.
_ => {
let old = self.behind_reference.replace(true);
// In case there are structural-match violations somewhere in this subpattern,
// we fall back to a const pattern. If we do not do this, we may end up with
// a !structural-match constant that is not of reference type, which makes it
// very hard to invoke `PartialEq::eq` on it as a fallback.
let val = match self.recur(tcx.deref_const(self.param_env.and(cv)), false) {
Ok(subpattern) => PatKind::Deref { subpattern },
Err(_) => PatKind::Constant { value: cv },
};
self.behind_reference.set(old);
val
if !pointee_ty.is_sized(tcx.at(span), param_env) {
// `tcx.deref_const()` below will ICE with an unsized type
// (except slices, which are handled in a separate arm above).
let msg = format!("cannot use unsized non-slice type `{}` in constant patterns", pointee_ty);
if self.include_lint_checks {
tcx.sess.span_err(span, &msg);
} else {
tcx.sess.delay_span_bug(span, &msg);
}
PatKind::Wild
} else {
let old = self.behind_reference.replace(true);
// In case there are structural-match violations somewhere in this subpattern,
// we fall back to a const pattern. If we do not do this, we may end up with
// a !structural-match constant that is not of reference type, which makes it
// very hard to invoke `PartialEq::eq` on it as a fallback.
let val = match self.recur(tcx.deref_const(self.param_env.and(cv)), false) {
Ok(subpattern) => PatKind::Deref { subpattern },
Err(_) => PatKind::Constant { value: cv },
};
self.behind_reference.set(old);
val
}
}
},
ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::FnDef(..) => {