Re: fix: propagate M4 env variable to flex subprocess

Hi,

On 2025-05-12 23:14:59 -0400, J. Javier Maestro wrote:
> The pgflex wrapper runs flex with an explicit environment, so it doesn't
> inherit environment variables from the parent process. However, flex can
> use the M4 env variable and/or the PATH (via execvp) to find the m4 macro
> processor.

> Thus, since flex honors the M4 env variable, it should be propagated to the
> subprocess environment if it's set in the parent environment. This patch
> fixes it.

I think it probably was not intentional to fully specify the environment,
rather than just *adding* FLEX_TMP_DIR to the caller's environment. Bilal, I
think you wrote this originally, do you recall?

It seems like an issue beyond just M4...

Greetings,

Andres Freund