On Thu, 11 Jul 2024 Richard Hodges wrote:

This usually happens because you're compiling with one standard library (e.g. libc++, the default on clang) while your boost libraries were compiled with another (e.g. libstdc++, the default on gcc).

I've recompiled my MacOS program for GCC (GNU C++17) and linked with libstdc++ to be compatible with the default build of Boost. Your suggestion WAS the solution to my reported slew of error messages. Thanks! QUESTION 1: But for building a standard MacOS or iPhone/iPad app, shouldn't I be building both my app and Boost for clang, so I can link with libc++? When I looked at the list of toolsets in the "getting started with unix variants", included with the 1_85_0 .zip package, there was no listing for toolset=clang or toolset=clang-darwin. Nor is there any mention of clang on: https://www.boost.org/doc/libs/1_85_0/more/getting_started/unix-variants.htm... QUESTION 2: So what is the proper toolset / build instructions to build for MacOS using the clang C++17 compiler? Stephen