Add missing Mandates for resize_and_overwrite

Author: frederick-vs-ja

stl/inc/xstring

@@ -2317,9 +2317,11 @@ public:
             _Mypair._Myval2._Mysize = _New_size;
         }
 
-        auto _Arg_ptr                   = _Mypair._Myval2._Myptr();
-        auto _Arg_size                  = _New_size;
-        const auto _Result_size         = _STD move(_Op)(_Arg_ptr, _Arg_size);
+        auto _Arg_ptr           = _Mypair._Myval2._Myptr();
+        auto _Arg_size          = _New_size;
+        const auto _Result_size = _STD move(_Op)(_Arg_ptr, _Arg_size);
+        static_assert(_Integer_like<decltype(_Result_size)>, "the return type of the operation must be integer-like");
+
         const auto _Result_as_size_type = static_cast<size_type>(_Result_size);
 #if _ITERATOR_DEBUG_LEVEL != 0
         _STL_VERIFY(_Result_size >= 0, "the returned size can't be smaller than 0");

tests/std/tests/P0980R1_constexpr_strings/test.cpp

@@ -17,6 +17,10 @@
 #include <type_traits>
 #include <utility>
 
+#if _HAS_CXX20
+#include <ranges> // for integer-class types
+#endif // _HAS_CXX20
+
 using namespace std;
 
 constexpr auto literal_input     = "Hello fluffy kittens";
@@ -2226,15 +2230,41 @@ constexpr void test_all() {
 }
 
 #if _HAS_CXX23
+template <class I>
 void test_gh_2524() { // COMPILE-ONLY
     // GH-2524 resize_and_overwrite generates warning C4018 when Operation returns int
     string s;
     s.resize_and_overwrite(1, [](char* buffer, size_t) {
         *buffer = 'x';
-        int i   = 1;
+        I i     = 1;
         return i;
     });
 }
+
+void test_gh_2524_all() { // COMPILE-ONLY
+    test_gh_2524<signed char>();
+    test_gh_2524<short>();
+    test_gh_2524<int>();
+    test_gh_2524<long>();
+    test_gh_2524<long long>();
+
+    test_gh_2524<unsigned char>();
+    test_gh_2524<unsigned short>();
+    test_gh_2524<unsigned int>();
+    test_gh_2524<unsigned long>();
+    test_gh_2524<unsigned long long>();
+
+    test_gh_2524<char>();
+#ifdef __cpp_char8_t
+    test_gh_2524<char8_t>();
+#endif // defined(__cpp_char8_t)
+    test_gh_2524<char16_t>();
+    test_gh_2524<char32_t>();
+    test_gh_2524<wchar_t>();
+
+    test_gh_2524<_Signed128>();
+    test_gh_2524<_Unsigned128>();
+}
 #endif // _HAS_CXX23
 
 int main() {