[libc++] Rename __s1/__s2 to __dest/__source in __copy_constexpr. NFC.

This consistently completes the renaming started in D115986.

diff --git a/libcxx/include/__string b/libcxx/include/__string
index 728367b..13ff7b3 100644 (file)
--- a/libcxx/include/__string
+++ b/libcxx/include/__string
@@ -290,11 +290,11 @@ char_traits<_CharT>::assign(char_type* __s, size_t __n, char_type __a)
 
 template <class _CharT>
 static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
-_CharT* __copy_constexpr(_CharT* __s1, const _CharT* __s2, size_t __n) _NOEXCEPT
+_CharT* __copy_constexpr(_CharT* __dest, const _CharT* __source, size_t __n) _NOEXCEPT
 {
   _LIBCPP_ASSERT(__libcpp_is_constant_evaluated(), "__copy_constexpr() should always be constant evaluated");
-  _VSTD::copy_n(__s2, __n, __s1);
-  return __s1;
+  _VSTD::copy_n(__source, __n, __dest);
+  return __dest;
 }
 
 template <class _CharT>