Re: [PATCH 12/12] mingw: allow `git.exe` to be used instead of the "Git wrapper"

Hi Junio,

On Thu, 6 Aug 2026, Junio C Hamano wrote:

> "Johannes Schindelin via GitGitGadget" <[email protected]>
> writes:
> 
> > @@ -3186,6 +3225,32 @@ static void setup_windows_environment(void)
> >  			setenv("HOME", tmp, 1);
> >  	}
> >  
> > +	if (!getenv("PLINK_PROTOCOL"))
> > +		setenv("PLINK_PROTOCOL", "ssh", 0);
> > +
> > +#ifdef ENSURE_MSYSTEM_IS_SET
> > +	if (!(tmp = getenv("MSYSTEM")) || !tmp[0]) {
> 
> Checking tmp[0] is a sign that we do not consider MSYSTEM set to an
> empty string a sane state and ENSURE_MSYSTEM_IS_SET is about
> correcting it, right?

"sane state" is quite the strong wording for such a minor issue.

The MSYSTEM variable is useful as an indicator, and is therefore used in
many scripts. Git itself only uses it as a tell-tale that a GUI should be
used in `git bisect visualize`, otherwise Git is totally fine with empty
or even non-sensical values.

But it _is_ a convenient thing to have, together with `MINGW_PREFIX` to
ensure that the respective `/*/bin/` directories are prepended to the
`PATH` variable. That's what this is all about.

> 
> > +		const char *home = getenv("HOME"), *path = getenv("PATH");
> > +		char buf[32768];
> > +		size_t off = 0;
> > +
> > +		setenv("MSYSTEM", ENSURE_MSYSTEM_IS_SET, 1);
> 
> In config.mak.uname, ENSURE_MSYSTEM_IS_SET is defined to "$(MSYSTEM)".
> 
> +	COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY \
> +		-DENSURE_MSYSTEM_IS_SET="\"$(MSYSTEM)\"" -DMINGW_PREFIX="\"$(patsubst /%,%,$(MINGW_PREFIX))\"" \
> 
> Can $(MSYSTEM) be an empty string or undefined at the build time,
> making ENSURE_MSYSTEM_IS_SET set to "" (two double-quotes)?

Sure it can. Just like `PATH` or `HOME` can be empty, or invalid. But the
person building the project has to go out of their way to make it so,
therefore I don't want to spend any more brain cells on that highly
unlikely scenario.

Ciao,
Johannes

> Which would mean we are exporting MSYSTEM defined to be an empty string
> as well with this setenv.
> 
> It seems ifeq($(uname_S),MINGW) side protects against this situation
> by placing the cflags definition
> 	
> +		COMPAT_CFLAGS += -DDETECT_MSYS_TTY \
> +			-DENSURE_MSYSTEM_IS_SET="\"$(MSYSTEM)\"" \
> 
> inside "ifneq (,$(MSYSTEM))..endif".  That way, ENSURE_MSYSTEM_IS_SET
> is not defined to "" (two double-quotes), so #ifdef ENSURE_MSYSTEM_IS_SET
> would not kick in.
> 
>