Check if find_last can find anything (#4561)

Co-authored-by: Stephan T. Lavavej <stl@nuwen.net>
microsoft · Apr 9, 2024 · d0995ff · d0995ff
1 parent 51b1a07
commit d0995ff
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Showing 3 changed files with 237 additions and 4 deletions.
diff --git a/stl/inc/algorithm b/stl/inc/algorithm
@@ -3028,7 +3028,12 @@ namespace ranges {
  if constexpr (is_same_v<_Pj, identity> && _Vector_alg_in_find_is_safe<_It, _Ty>
  && sized_sentinel_for<_Se, _It>) {
  if (!_STD is_constant_evaluated()) {
- const auto _Count = _Last - _First;
+ const auto _Count = _Last - _First;
+
+ if (!_STD _Could_compare_equal_to_value_type<_It>(_Value)) {
+ return {_First + _Count, _First + _Count};
+ }
+
  const auto _First_ptr = _STD _To_address(_First);
  const auto _Last_ptr = _First_ptr + _Count;
 

diff --git a/tests/std/tests/Dev11_0316853_find_memchr_optimization/env.lst b/tests/std/tests/Dev11_0316853_find_memchr_optimization/env.lst
@@ -2,3 +2,6 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 RUNALL_INCLUDE ..\usual_matrix.lst
+RUNALL_CROSSLIST
+* PM_CL=""
+* PM_CL="/D_USE_STD_VECTOR_ALGORITHMS=0"