[PATCH] D28222: [libcxx] Re-implement LWG 2770 again: Fix tuple_size to work with structured bindings

[Eric Fiselier via Phabricator via cfe-commits]

EricWF added inline comments.


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Comment at: include/__tuple:34
+    const _Tp,
+    typename enable_if<!is_volatile<_Tp>::value>::type,
+    decltype(tuple_size<_Tp>::value)>>
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Without this extra `enable_if`, GCC will diagnose each of these three specializations as ambiguous. 


https://reviews.llvm.org/D28222