Re: [Qemu-devel] 'make help' generate unrelated files

[Peter Maydell]

On 29 July 2017 at 02:55, Philippe Mathieu-Daudé <address@hidden> wrote:
> Is it necessary to generate this files to run 'make help'?
>
> $ ./configure
> [...]
> $ make help
>         CHK version_gen.h
>         UPD version_gen.h
>          DEP util.c
>         CHK version_gen.h

This happens because we have a rule that says
"Makefile: $(GENERATED_FILES)"
which is how we ensure that the autogenerated header
files are always built before any .c file is compiled.
The unfortunate side effect is that we rebuild the
generated files before processing *any* makefile
target, even those like 'clean' and 'help' that
don't actually require them.

I did once have a go at fixing this some years back:
http://patchwork.ozlabs.org/patch/365288/
but as you'll note from the last comment by me
in that mail thread it had a fatal flaw for
the "build from clean" case...

thanks
-- PMM