Re: Warnings in mingw64 builds on master

[Eli Zaretskii]

> From: Óscar Fuentes <ofv@wanadoo.es>
> Date: Sun, 16 Aug 2020 18:45:31 +0200
> 
> The information gained about the contents of fd_info[fd] from that test
> is discarded when the compiler finds a call to an external function
> (DebPrint) a few lines below, since DebPrint (or one of the functions it
> calls) might change the contents of the global fd_info array.
> 
> If the OP was not building with EMACSDEBUG defined, the warning would be
> bogus indeed, since DebPrint is a no-op on that case.

I expect Andy was building without EMACSDEBUG, since he was almost
certainly building an optimized binary, see below.

> which compiled with `gcc -c -Wall -Wmaybe-uninitialized' (gcc 10.1)
> shows no warnings

I think you need to use -O2 (or some optimization switch) to have this
warning.  At least that's how it used to be in the past, I don't have
GCC 10 installed to check.