Re: [PATCH 3/3] configure: automatically parse command line for meson -D options

[Eric Blake <eblake@redhat.com>]

On 9/13/20 5:05 AM, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   Makefile                                |   6 ++
>   configure                               |  71 +++++--------
>   docs/devel/build-system.rst             |  35 +------
>   meson-buildoptions.json                 | 130 ++++++++++++++++++++++++
>   scripts/configure-parse-buildoptions.py |  94 +++++++++++++++++
>   5 files changed, 258 insertions(+), 78 deletions(-)
>   create mode 100644 meson-buildoptions.json
>   create mode 100644 scripts/configure-parse-buildoptions.py
> 
> diff --git a/Makefile b/Makefile
> index d6c5c9fdef..b22e5b272e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -80,6 +80,12 @@ ifneq ($(MESON),)
>   Makefile.mtest: build.ninja scripts/mtest2make.py
>   	$(MESON) introspect --tests --benchmarks | $(PYTHON) scripts/mtest2make.py > $@
>   -include Makefile.mtest
> +
> +# jq is used to keep the result stable
> +meson-buildoptions.json: meson_options.txt
> +	$(MESON) introspect --buildoptions . | \
> +	    jq 'map(select(.section == "user")) | sort_by(.name)' \
> +	    > $(SRC_PATH)/meson-buildoptions.json

Are we guaranteed to have jq on the system?  This appears to be the 
first use of it in qemu.git.

> @@ -108,6 +78,11 @@ In meson.build::
>     # Summary
>     summary_info += {'SDL image support': sdl_image.found()}
>   
> +The configure script automatically converts command line options to
> +Meson options as long as the `meson-buildoptions.json` file in the
> +root source directory is up-to-date.  You can simply type
> +`make meson-buildoptions.json` to update it; the `jq` program
> +is needed.

Oh, you're using it for an optional step, that most people don't have to 
run, but where a developer needing to regenerate things can be likely to 
understand how to get it.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org