Re: [PATCH] run-command.c: fix missing include under `NO_PTHREADS`

>
> On Tue, May 16, 2023 at 12:12:02PM -0700, Junio C Hamano wrote:
> > Taylor Blau <me@ttaylorr.com> writes:
> >
> > > When building git with `NO_PTHREADS=YesPlease`, we fail to build
> > > run-command.o since we don't have a definition for ALLOC_GROW:
> > >
> > >     $ make NO_PTHREADS=1 DEVELOPER=1 run-command.o
> > >     GIT_VERSION = 2.41.0.rc0.1.g787eb3beae.dirty
> > >         CC run-command.o
> > >     run-command.c: In function ‘git_atexit’:
> > >     run-command.c:1103:9: error: implicit declaration of function ‘ALLOC_GROW’ [-Werror=implicit-function-declaration]
> > >      1103 |         ALLOC_GROW(git_atexit_hdlrs.handlers, git_atexit_hdlrs.nr + 1, git_atexit_hdlrs.alloc);
> > >           |         ^~~~~~~~~~
> > >     cc1: all warnings being treated as errors
> > >     make: *** [Makefile:2715: run-command.o] Error 1
> >
> > I am OK to give a reproduction recipe, i.e. the "$ make" command
> > line, to make it easy for people, who cannot remember how to define
> > make variables from the command line, to try out themselves, but I
> > hate the "build transcript" in the log message, when a few lines of
> > prose suffices.
>
> Much appreciated. Here's a version with your changes include that is
> suitable for queueing:
>
> --- 8< ---
>
> Subject: [PATCH] run-command.c: fix missing include under `NO_PTHREADS`
>
> Git 2.41-rc0 fails to compile run-command.c with `NO_PTHREADS` defined,
> i.e.
>
>   $ make NO_PTHREADS=1 run-command.o
>
> as `ALLOC_GROW()` macro is used in the `atexit()` emulation but the
> macro definition is not available.
>
> This bisects to 36bf195890 (alloc.h: move ALLOC_GROW() functions from
> cache.h, 2023-02-24), which replaced includes of <cache.h> with
> <alloc.h>, which is the new home of `ALLOC_GROW()` (and
> `ALLOC_GROW_BY()`).
>
> We can see that run-command.c is the only one that try to use these
> macros without including <alloc.h>.
>
>   $ git grep -l -e '[^_]ALLOC_GROW(' -e 'ALLOC_GROW_BY(' \*.c | sort >/tmp/1
>   $ git grep -l 'alloc\.h' \*.c | sort >/tmp/2
>   $ comm -23 /tmp/[12]
>   compat/simple-ipc/ipc-unix-socket.c
>   run-command.c
>
> The "compat/" file only talks about the macro in the comment,
> and is not broken.
>
> We could fix this by conditionally including "alloc.h" when
> `NO_PTHREADS` is defined.  But we have relatively few examples of
> conditional includes throughout the tree[^1].
>
> Instead, include "alloc.h" unconditionally in run-command.c to allow it
> to successfully compile even when NO_PTHREADS is defined.
>
> [^1]: With `git grep -E -A1 '#if(n)?def' -- **/*.c | grep '#include' -B1`.
>
> Reported-by: Randall S. Becker <randall.becker@nexbridge.ca>
> Co-authored-by: Junio C Hamano <gitster@pobox.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> Signed-off-by: Taylor Blau <me@ttaylorr.com>
> ---
>  run-command.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/run-command.c b/run-command.c
> index d4247d5fcc..60c9419866 100644
> --- a/run-command.c
> +++ b/run-command.c
> @@ -16,6 +16,7 @@
>  #include "packfile.h"
>  #include "hook.h"
>  #include "compat/nonblock.h"
> +#include "alloc.h"
>
>  void child_process_init(struct child_process *child)
>  {
> --
> 2.41.0.rc0.dirty