[libcxx-commits] [libcxx] [libc++] Fix basic_string not allowing max_size() elements to be stored (PR #125423)

[Mark de Wever via libcxx-commits]

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@@ -1305,10 +1305,10 @@ public:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type max_size() const _NOEXCEPT {
     size_type __m = __alloc_traits::max_size(__alloc_);
     if (__m <= std::numeric_limits<size_type>::max() / 2) {
-      return __m - __alignment;
+      return __m - __alignment - 1;
     } else {
       bool __uses_lsb = __endian_factor == 2;
-      return __uses_lsb ? __m - __alignment : (__m / 2) - __alignment;
+      return __uses_lsb ? __m - __alignment - 1 : (__m / 2) - __alignment - 1;
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mordante wrote:

Since this is an observable change I'd like a note in the release notes.


https://github.com/llvm/llvm-project/pull/125423