jfb added inline comments.
================
Comment at: lib/Sema/SemaChecking.cpp:10668
+ if (Source->isAtomicType() || Target->isAtomicType())
+ S.Diag(E->getBeginLoc(), diag::warn_atomic_implicit_seq_cst);
+
----------------
rjmccall wrote:
> Why would the target be an atomic type? And if it is an atomic type, isn't
> that an initialization of a temporary? In what situation does it make sense
> to order the initialization of a temporary?
In this case:
```
void bad_assign_1(int i) {
atom = i; // expected-warning {{implicit use of sequentially-consistent
atomic may incur stronger memory barriers than necessary}}
}
```
We want to warn on assignment to atomics being implicitly `seq_cst`.
Though you're right, initialization shouldn't warn because it isn't atomic. The
issue is that `ATOMIC_VAR_INIT` is what needs to get used, and that's weird to
test. I'll add a test that just assigns (which is what `ATOMIC_VAR_INIT`
expands to for clang), and I'll need to update the code to detect that pattern
and avoid warning in that case. I guess I have to look at the `Expr` and figure
out if the LHS is a `Decl` or something like that.
Repository:
rC Clang
https://reviews.llvm.org/D51084
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