[m-rev.] for review: support wildcard argument expansion with MSVC

[Zoltan Somogyi]

On Tue, 6 Jan 2026 03:03:19 +1100, Julien Fischer <jfischer at opturion.com> wrote:
> I added it, because the following does not currently work at the
> Windows command prompt:
> 
>     mercury -f *.m
> 
> (Offhand, I can't think of anywhere else that users of mmc would need wildcard
> expansion.)

mmc --make-int *.m? No, this does not invoke ml, but then, I don't think
mercury -f *.m does either. 

> > It does not help even us, Mercury developers, when working in e.g. the browser
> 
> There are no executables in the browser directory.

But e.g. mercury -f *.m is useful even in that case.

> The ideal solution would be to provide wildcard expansion as part
> of Mercury's standard library and then programs can selectively process
> the argument vector at startup based on whether the underlying platform
> does wildcard expansion or not.  This would work for all backends and
> not rely on various compiler-specific runtime extensions.
> 
> Short of that, it's certainly possible to teach the compiler about all this.
> (In fact, it's probably simpler than supporting it in mmake.)

Agreed on both counts.

> > Second, it would be much better if we simply recorded the current platform
> > (including in this case that MSVC was specified as the C compiler) in the ml script
> > at configure time,
> 
> We record the C compiler type in the ml script at configure time.
> 
> > and let it take care of all its implications, this new one
> > being just one of them.
> 
> Because that would affect any use of the ml script, not just building the
> compiler.  What if a user does *not* want this runtime extension enabled
> with their program?

We could

- extend the configure script with a flag that sets the default for this to
either on or off.

- embed this default in ml at configure time, and

- let an environment variable override the default.

> > Is there some reason why this wouldn't work?
> 
> I think it would work, however I think you still need the ability to control
> whether it is enabled or not.

The above would do that. It would do that for *all* uses of ml, not
just when ml is invoked by mmc.

> > Please document the meaning of this variable.
> 
> # MSVC_SETARGV is set to the name of the object file that contains the
> # Microsoft C runtime extension that implements wildcard argument expansion.
> # There are several versions of this object file, the one we choose below must
> # match the program entry point set in value of the variable main_func in
> # ../util/mkinit.c

That's fine, but I would explicitly specify that "" means the absence of such
an object file.

Zoltan.