boost-container build failure by using emscripten about container HOT 4 CLOSED

Error on vcpkg

from container.

Basically it uses windows code because it doesn't see pthreads.

from container.

Sorry but the library does not support emscriptem and it's not tested in that platform.

It seems that Emscriptem wronly defines "_POSIX_THREADS " as -1, since POSIX defines that meaning quite well:

If a symbolic constant is defined with the value -1, the option is not supported. Headers, data types, and function interfaces required only for the option need not be supplied. An application that attempts to use anything associated only with the option is considered to be requiring an extension.

from container.

The _POSIX_THREADS value on emscripten changes with -pthread which is the official way to enable it.
https://emscripten.org/docs/porting/pthreads.html#compiling-with-pthreads-enabled
However, even cmake's

  set(THREADS_PREFER_PTHREAD_FLAG 1)
  find_package(Threads REQUIRED)

doesn't add the flag, so it has to be done explicitly.

https://github.com/microsoft/vcpkg/pull/38806/files#diff-8728338e87238c609e4a490888aebbc1d428166bdc0a0b6b1303281b27732a0e

The other point is that the (CMake) build behaviour is misleading: If it doesn't find POSIX threads, it immediately uses Windows code, even on non-Windows platforms. This leads to unexpected error messages which do not point to the lack of POSIX threads.

from container.