Fix detection of __attribute__((may_alias)) to properly look through
type sugar.
We previously missed the attribute in a lot of cases in C++, because
there's often other type sugar there (eg, ElaboratedType).
diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
index 09de959..7d730cb 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.cpp
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -78,17 +78,18 @@
static bool TypeHasMayAlias(QualType QTy) {
// Tagged types have declarations, and therefore may have attributes.
- if (const TagType *TTy = dyn_cast<TagType>(QTy))
- return TTy->getDecl()->hasAttr<MayAliasAttr>();
-
- // Typedef types have declarations, and therefore may have attributes.
- if (const TypedefType *TTy = dyn_cast<TypedefType>(QTy)) {
- if (TTy->getDecl()->hasAttr<MayAliasAttr>())
+ if (auto *TD = QTy->getAsTagDecl())
+ if (TD->hasAttr<MayAliasAttr>())
return true;
- // Also, their underlying types may have relevant attributes.
- return TypeHasMayAlias(TTy->desugar());
- }
+ // Also look for may_alias as a declaration attribute on a typedef.
+ // FIXME: We should follow GCC and model may_alias as a type attribute
+ // rather than as a declaration attribute.
+ while (auto *TT = QTy->getAs<TypedefType>()) {
+ if (TT->getDecl()->hasAttr<MayAliasAttr>())
+ return true;
+ QTy = TT->desugar();
+ }
return false;
}