aaron.ballman added a comment.
This is a bit of an odd situation -- the condition variable *is* used (e.g.,
its value is loaded to determine whether to go into the if branch or the else
branch), so we should not be marking it as unused in
`Sema::CheckConditionVariable()`. Instead, I think we need to decide what
constitutes "unused" in this case. Consider:
struct RAII {
int &x;
RAII(int &ref) : x(ref) {}
~RAII() { x = 0; }
operator bool() const { return true; }
};
void func() {
int i = 12;
if (RAII name{i}) {
}
}
I don't think `name` is unused in the same way that `i` is unused in `if (int i
= 1) {}`. So I think we only want this to apply to scalars and not class types.
I think the changes should be happening in `Sema::ShouldDiagnoseUnusedDecl()`
(and you might need to thread the `Scope` object through to that call -- my
naive thinking is that a variable declaration in a condition scope should be
diagnosed as unused if it is used but not referenced, but I could be off-base).
================
Comment at: clang/docs/ReleaseNotes.rst:340
with ``__attribute__((cleanup(...)))`` to match GCC's behavior.
+- Clang now warns on unused variables declaread and initialized in condition
+ expressions.
----------------
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D152495/new/
https://reviews.llvm.org/D152495
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