bug#46495: 28.0.50; [native-comp] Build fails for 32bit --with-wide-int

[Eli Zaretskii <eliz@gnu.org>]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: andrewjmoreton@gmail.com, dmalcolm@redhat.com, 46495@debbugs.gnu.org
> Date: Wed, 31 Mar 2021 10:33:43 +0000
> 
> >>   libgccjit-0.dll: note: disable pass tree-isolate-paths for functions in the range of [0, 4294967295]
> >
> > Oh, I see: it's because batch-native-compile runs the final
> > compilation phase in a subprocess.  But doesn't that mean the
> > non-default setting of comp-debug will not have its effect in this
> > case?
> 
> `comp-debug' at that point is captured in the compilation context
> `comp-ctxt', we have a slot for that in the structure.

OK, thanks.

> > Btw, I find the doc strings of the various top-level native-compile
> > functions not very helpful when I need to understand under what
> > circumstances they run the compilation asynchronously.  I always need
> > to read the code, and read it carefully, to figure that out.  Can this
> > please be improved?
> 
> Sure, if you have a list of the one that you have found troublesome
> (and/or some suggestion) I'll try to improve them.

I think these:

  comp--native-compile, native-compile, batch-native-compile,
  batch-byte-native-compile-for-bootstrap

The first of these is an internal function, but it's used a lot, and
its doc string describes most of what it does -- except the async
aspect.

One question I have, that perhaps will be answered by the enhanced doc
strings, is this: how to run a batch compilation of a non-preloaded
file such that no subprocesses at all are used?  There's
comp-async-jobs-number, but a zero value doesn't disable async
compilation, it means something else.

Another question is: the documentation sometimes mentions async
compilation and sometimes mentions deferred compilation -- but these
are not the same, right?