if constexpr since C++17

Author: Advenam Tacet

libcxx/include/deque

@@ -1012,7 +1012,7 @@ private:
   _LIBCPP_HIDE_FROM_ABI void __annotate_delete() const _NOEXCEPT {
 #ifndef _LIBCPP_HAS_NO_ASAN
     // The default allocator does not require unpoisoning before returning memory.
-    if _LIBCPP_CONSTEXPR (is_same<allocator_type, allocator<_Tp> >::value)
+    if _LIBCPP_CONSTEXPR_SINCE_CXX17 (is_same<allocator_type, allocator<_Tp> >::value)
       return;
     if (empty()) {
       for (size_t __i = 0; __i < __map_.size(); ++__i) {

libcxx/include/string

@@ -1913,7 +1913,7 @@ private:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_delete() const _NOEXCEPT {
 #if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
     // The default allocator does not require unpoisoning before returning memory.
-    if _LIBCPP_CONSTEXPR (!is_same<allocator_type, allocator<__default_allocator_type> >::value)
+    if _LIBCPP_CONSTEXPR_SINCE_CXX17 (!is_same<allocator_type, allocator<__default_allocator_type> >::value)
       if (!__libcpp_is_constant_evaluated() && (__asan_short_string_is_annotated() || __is_long()))
         __annotate_contiguous_container(data() + size() + 1, data() + capacity() + 1);
 #endif

libcxx/include/vector

@@ -854,7 +854,7 @@ private:
   _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __annotate_delete() const _NOEXCEPT {
 #ifndef _LIBCPP_HAS_NO_ASAN
     // The default allocator does not require unpoisoning before returning memory.
-    if _LIBCPP_CONSTEXPR (!is_same<allocator_type, __default_allocator_type>::value)
+    if _LIBCPP_CONSTEXPR_SINCE_CXX17 (!is_same<allocator_type, __default_allocator_type>::value)
       __annotate_contiguous_container(data(), data() + capacity(), data() + size(), data() + capacity());
 #endif
   }