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Sema: Fix a couple of crash-on-invalid problems with class inheritance

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It is possible for ClassDecl::getSuperclassDecl() to succeed but for
ClassDecl::getSuperclass() to fail. This happens if the superclass is
a generic type and one of the generic arguments could not be resolved,
or does not satisfy the generic requirements, for example; in that
case, a BoundGenericType cannot be formed.

In a couple of places we were not prepared for this possibility.
Let's recover by making judicious use of ErrorType.

Fixes <rdar://problem/73169149>.
This commit is contained in:
Slava Pestov
2021-01-17 18:00:32 -05:00
parent 0ee3b22384
commit c8aee4180e
4 changed files with 48 additions and 10 deletions
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8
lib/Sema/CodeSynthesis.cpp
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@@ -62,6 +62,12 @@ Expr *swift::buildSelfReference(VarDecl *selfDecl,
selfTy = metaTy->getInstanceType();
}
selfTy = selfTy->getSuperclass();
if (!selfTy) {
// Error recovery path. We end up here if getSuperclassDecl() succeeds
// but getSuperclass() fails (because, for instance, a generic parameter
// of a generic nominal type cannot be resolved).
selfTy = ErrorType::get(ctx);
}
if (isMetatype)
selfTy = MetatypeType::get(selfTy);
@@ -70,7 +76,7 @@ Expr *swift::buildSelfReference(VarDecl *selfDecl,
// If no conversion type was specified, or we're already at that type, we're
// done.
if (!convertTy || convertTy->isEqual(selfTy))
if (!convertTy || convertTy->isEqual(selfTy) || selfTy->is<ErrorType>())
return superRef;
// Insert the appropriate expr to handle the upcast.