[m-rev.] for review: write direct to .err files

[Peter Wang]

On Fri, 15 Sep 2023 16:36:39 +1000 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> 
> On 2023-09-15 15:06 +10:00 AEST, "Julien Fischer" <jfischer at opturion.com> wrote:
> > I cannot think of an instance when such call pair nesting could occur.
> > Peter, can you?
> 
> The circumstances I was thinking of were, roughly, where
> 
> - making A.c  requires A.int
> - making A.c requires B.mh which requires A.opt.
> 
> I don't know enough about mmc --make to rule out
> either scenario.

There's no reason to open the error stream for a target until its
dependencies have successfully been made, and it doesn't.

make_module_target
 1. calls make_dependency_files first
    (and make_dependency_files calls make_module_target recursively),
 2. before calling build_target, which opens/closes the error stream.
    build_target doesn't make dependencies.

(This is from a quick examination of the code. I only vaguely remember
how mmc --make works.)

Peter