[libc++] Rename variables to use the snake case instead of camel case

[huixie90]

Summary

For some reason the pre-commit CI of https://reviews.llvm.org/D129233 was all green so I didn't spot this
https://reviews.llvm.org/B174525

[philnik]

LGTM. I added the check in D129051. You probably just didn't rebase onto it.

[Mordante]

LGTM.

libcxx/include/__algorithm/set_intersection.h

29

These names look suspicious, the struct has underscores, the members not. Since this patch fixes a CI breakage I prefer to land this patch as is and improve this in a separate patch.

For your information __out is a name you can't use. It's used by Microsoft and will fail in the CI in our nasty-macro test.

[Mordante]

@huixie90 since this fixes the breaking of the ToT I've landed this on your behalf.

Please have a look at the review comment I left earlier.

libcxx/include/__algorithm/set_intersection.h

 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _InIter1, class _InIter2, class _OutIter>
 struct __set_intersection_result {
   _InIter1 in1;
   _InIter2 in2;
   _OutIter out;
 
   // need a constructor as C++03 aggregate init is hard
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
-  __set_intersection_result(_InIter1&& __inIter1, _InIter2&& __inIter2, _OutIter&& __outIter)
-      : in1(std::move(__inIter1)), in2(std::move(__inIter2)), out(std::move(__outIter)) {}
+  __set_intersection_result(_InIter1&& __in_iter1, _InIter2&& __in_iter2, _OutIter&& __out_iter)
+      : in1(std::move(__in_iter1)), in2(std::move(__in_iter2)), out(std::move(__out_iter)) {}
 };
 
 template < class _IterOper, class _Compare, class _InIter1, class _Sent1, class _InIter2, class _Sent2, class _OutIter>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17 __set_intersection_result<_InIter1, _InIter2, _OutIter>
 __set_intersection(
     _InIter1 __first1, _Sent1 __last1, _InIter2 __first2, _Sent2 __last2, _OutIter __result, _Compare&& __comp) {
   while (__first1 != __last1 && __first2 != __last2) {
     if (__comp(*__first1, *__first2))