riccibruno added a comment.
In D60573#1463569 <https://reviews.llvm.org/D60573#1463569>, @rjmccall wrote:
> Hmm. Does this never impact code that's just using a locally-defined type
> within its scope? I guess if ADL is involved, unqualified lookup must have
> reached the scope of the innermost namespace, and so it would be searching
> that namespace anyway.
>
> In that case, I think I'm mollified that the source-compatibility risk is low
> and we should just unconditionally apply the new rule. LGTM.
I am not sure about what you mean. It is certainly possible to construct a
piece of C++11 code which breaks with this patch. A possible example is:
constexpr int f(void *) { return 1; }
static auto lambda = []() { struct S {} s; return s; };
using S = decltype(lambda());
template <typename T> void test() {
constexpr T *p = nullptr;
static_assert(f(p) == 1, "");
}
constexpr int f(S *) { return 2; }
template void test<S>();
Clang currently accept this because ADL does not currently find the second
better matching `f`. After this patch it will be found and the `static_assert`
will fail (which is the behavior of gcc, and as far as I can tell the specified
behavior).
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D60573/new/
https://reviews.llvm.org/D60573
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