================
@@ -450,6 +453,116 @@ class StmtComparer {
};
} // namespace
+static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
+ const Attr *Attr1, const Attr *Attr2) {
+ // Two attributes are structurally equivalent if they are the same kind
+ // of attribute, spelled with the same spelling kind, and have the same
+ // arguments. This means that [[noreturn]] and __attribute__((noreturn)) are
+ // not structurally equivalent, nor are [[nodiscard("foo")]] and
+ // [[nodiscard("bar")]].
+ if (Attr1->getKind() != Attr2->getKind())
+ return false;
+
+ if (Attr1->getSyntax() != Attr2->getSyntax())
+ return false;
+
+ if (Attr1->getSpellingListIndex() != Attr2->getSpellingListIndex())
+ return false;
+
+ auto GetAttrName = [](const Attr *A) {
+ if (const IdentifierInfo *II = A->getAttrName())
+ return II->getName();
+ return StringRef{};
+ };
+
+ if (GetAttrName(Attr1) != GetAttrName(Attr2))
+ return false;
+
+ // FIXME: check the attribute arguments. Attr does not track the arguments on
+ // the base class, which makes this awkward. We may want to tablegen a
+ // comparison function for attributes? In the meantime, we're doing this the
+ // cheap way by pretty printing the attributes and checking they produce
----------------
jyknight wrote:
> safe by default (require attributes to be the same) or we can be unsafe by
> default (ignore attributes).
If we treat two types as incompatible when they ought to be compatible, it
potentially could result in silent miscompilation of a valid program, since
loading from memory requires that you use a type compatible with the type which
was used to store. OTOH, if we treat two types as being compatible when they
should be incompatible, the result is that we may incorrectly accept some
invalid programs which we could've rejected. The latter is _not useful_ towards
the goal of assisting the developer in writing correct code, but not unsafe on
its own.
Though...I suppose getting it wrong here may not be able to actually cause
miscompilation for Clang, since we emit TBAA metadata using a different (and
weaker) concept of type-compatibility anyhow.
https://github.com/llvm/llvm-project/pull/132939
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
