On 05/09/20 09:20 PM, Steven Levine wrote:

A quick look at stdlib.h indicates that the _beginthread declaration is
controlled by:

#if (!defined (__STRICT_ANSI__) && !defined (_POSIX_SOURCE)) || defined
(_WITH_UNDERSCORE) || defined(__USE_EMX)

Is it possible one of these #defines is missing?

Quite possible, but attempts as setting various ones has just resulted in an earlier error. I'm probably just missing something simple.

There are also lots of related warnings like

These are all side effects of the implicit declaration of _beginthread.

Yet these turn into a fatal error if I declare __USE_EMX or such.