Re: branch emacs-28 build broken on MinGW64 with gcc 11

[Eli Zaretskii <eliz@gnu.org>]

> From: wsw0108@qq.com
> Date: Tue, 23 Nov 2021 20:19:49 +0800
> 
> The error messages as below:
> 
> $ make
> make -C nt all
> make[1]: Entering directory '/d/GitHub/emacs/nt'
> make[1]: Nothing to be done for 'all'.
> make[1]: Leaving directory '/d/GitHub/emacs/nt'
> make -C lib all
> make[1]: Entering directory '/d/GitHub/emacs/lib'
> make[1]: Nothing to be done for 'all'.
> make[1]: Leaving directory '/d/GitHub/emacs/lib'
> make -C lib-src all
> make[1]: Entering directory '/d/GitHub/emacs/lib-src'
>   CC       ntlib.o
> In file included from ../lib/time.h:44,
>                  from ntlib.c:35:
> ../lib/unistd.h:624:3: error: #error "Please include config.h first."
>   624 |  #error "Please include config.h first."
>       |   ^~~~~
> ../lib/unistd.h:626:24: error: expected ';' before 'extern'
>   626 | _GL_INLINE_HEADER_BEGIN

The Gnulib's unistd.h should not be generated in the MinGW builds.
The file nt/gnulib-cfg.mk has this line:

  OMIT_GNULIB_MODULE_unistd = true

which causes the build process not to generate lib/unistd.h from
lib/unistd.in.h.  You need to investigate why this file was
nevertheless generated on your system.  Perhaps that tree was
previously used for building another configuration, and you didn't say
"make extraclean" before reconfiguring?  Or maybe something is wrong
with your build environment?

I'd start with cloning a fresh Git repository and trying anew.

Bottom line: the problem is most probably specific to your system.

Thanks.