Bug Report – C++20 build on QNX 8 / qcc 12 fails with -Werror=alloc-size-larger-than

[Sherif-MoOo]

Describe the bug
Building the open-aa-tests/core_platform/core_string_view_test target with -std=c++20 for the
QNX 8.0 aarch64 tool-chain (QCC 12.2.0, libc++ 15) aborts at 94 % with
error: argument 1 value '18446744073709551580' exceeds maximum object size … [-Werror=alloc-size-larger-than=].
The same sources compile cleanly in C++17 on the same tool-chain and in C++20 on GNU/Linux

Analysis / suspected cause

• The diagnostic originates inside libc++’s basic_stringbuf::overflow, triggered
  by our extensive std::wostringstream tests