Re: [PATCH] Update scripts/meson-buildoptions.sh

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 3 Jan 2023 at 16:12, Alessandro Di Federico <ale@rev.ng> wrote:
>
> On Tue, 3 Jan 2023 10:51:36 -0500
> Stefan Hajnoczi <stefanha@gmail.com> wrote:
>
> > QEMU's Makefile used to a use a technique where it generated
> > "timestamp" files and used cmp(1) to check if rebuilding was
> > necessary:
> > 1. Always generate meson-buildoptions.sh-timestamp.
>
> `meson-buildoptions.sh-timestamp` would be the full expected output,
> right? It's not just a date or something.
> AFAIU that would make sure that if nothing changed in the output you
> don't trigger other targets depending on `meson-buildoptions.sh`. It's
> a solution for a different problem.
>
> The problem with always rebuilding `meson-buildoptions.sh` is that we
> spend 1 extra second on every build, even those that doesn't need to
> rebuild anything else.
> Not unacceptable, but I think we should strive not to commit generated
> files and move the file to the build directory, unless there's a reason
> why this is not viable that I'm not seeing.

The other problem with this file is that it appears to
be generated differently depending on the host distro
(specifically the default value for the --libdir option).
That also would seem to nudge towards "don't commit a
generated file".

thanks
-- PMM