Re: [Qemu-devel] [PATCH 3/7] configure: integrate Meson in the build system

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> The Meson build system is integrated in the existing configure/make steps
> by invoking Meson from the configure script and converting Meson's build.ninja
> rules to an included Makefile.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  Makefile             |   9 +
>  configure            |  30 ++
>  meson.build          |   9 +
>  scripts/ninjatool.py | 964 +++++++++++++++++++++++++++++++++++++++++++++++++++

Uff.

>  4 files changed, 1012 insertions(+)
>  create mode 100644 meson.build
>  create mode 100644 scripts/ninjatool.py
>
> diff --git a/Makefile b/Makefile
> index 8e2fc66..b8f802c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -48,6 +48,15 @@ git-submodule-update:
>  endif
>  endif
>  
> +export NINJA=./ninjatool
> +Makefile.ninja: build.ninja ninjatool
> +	./ninjatool -t ninja2make --omit dist uninstall < $< > $@
> +-include Makefile.ninja
> +
> +ninjatool: $(SRC_PATH)/scripts/ninjatool.py
> +	sed -e '1c\' -e '#! $(PYTHON)' $< > $@
> +	chmod +x $@

Why do we need this here, but not for other Python scripts?

We have 39 Python scripts with #!/usr/bin/env python, one with
#!/usr/bin/env python2, and 12 with #!/usr/bin/python.  The Makefiles
generally use $(PYTHON) SCRIPT ARGS...

> +
>  .git-submodule-status: git-submodule-update config-host.mak
>  
>  # Check that we're not trying to do an out-of-tree build from
> diff --git a/configure b/configure
> index 0814a5f..b8c3c58 100755
> --- a/configure
> +++ b/configure
> @@ -493,6 +493,7 @@ docker="no"
>  debug_mutex="no"
>  libpmem=""
>  default_devices="yes"
> +meson=meson
>  
>  # cross compilers defaults, can be overridden with --cross-cc-ARCH
>  cross_cc_aarch64="aarch64-linux-gnu-gcc"
> @@ -983,6 +984,8 @@ for opt do
>    ;;
>    --python=*) python="$optarg"
>    ;;
> +  --meson=*) meson="$optarg"
> +  ;;
>    --gcov=*) gcov_tool="$optarg"
>    ;;
>    --smbd=*) smbd="$optarg"
> @@ -1685,6 +1688,7 @@ Advanced options (experts only):
>    --make=MAKE              use specified make [$make]
>    --install=INSTALL        use specified install [$install]
>    --python=PYTHON          use specified python [$python]
> +  --meson=PYTHON           use specified meson [$meson]
>    --smbd=SMBD              use specified smbd [$smbd]
>    --with-git=GIT           use specified git [$git]
>    --static                 enable static build [$static]
> @@ -1850,6 +1854,11 @@ then
>      error_exit "Python not found. Use --python=/path/to/python"
>  fi
>  
> +if ! has "$meson"
> +then
> +    error_exit "Meson not found. Use --meson=/path/to/meson"
> +fi
> +
>  # Note that if the Python conditional here evaluates True we will exit
>  # with status 1 which is a shell 'false' value.
>  if ! $python -c 'import sys; sys.exit(sys.version_info < (2,7))'; then
> @@ -7983,6 +7992,27 @@ echo "# Automatically generated by configure - do not modify" > "$iotests_common
>  echo >> "$iotests_common_env"
>  echo "export PYTHON='$python'" >> "$iotests_common_env"
>  
> +# bootstrap ninjatool, we need it before Make runs
> +if ! test -x ninjatool; then
> +  sed -e '1c\' -e "#! $python" ${source_path}/scripts/ninjatool.py > ninjatool
> +  chmod +x ninjatool
> +fi
> +rm -rf meson-private meson-info meson-logs

Ignorant question: why do we need configure remove this stuff?

> +NINJA=$PWD/ninjatool $python $meson setup \

This prints

    /usr/bin/python3: can't open file 'meson': [Errno 2] No such file or directory

for me, then goes on happily.

For what it's worth:

    $ type meson
    meson is /usr/bin/meson

Are you sure you want to override /usr/bin/meson's #! line?

If I drop $python, I get

    meson.build:1:0: ERROR: Meson version is 0.50.1 but project requires >=0.50.999.

which is expected.

It's too hot right for me now to figure out how to obtain a suitable
version.

> +	--prefix "$prefix" \
> +	--libdir "$libdir" \
> +	--libexecdir "$libexecdir" \
> +	--bindir "$bindir" \
> +	--includedir "$includedir" \
> +	--datadir "$datadir" \
> +	--mandir "$mandir" \
> +	--sysconfdir "$sysconfdir" \
> +	--localstatedir "$local_statedir" \
> +	$(test "$strip_opt" = yes && echo --strip) \
> +	--buildtype $(if test "$debug" = yes; then echo debug; else echo release; fi) \
> +	"$PWD" "$source_path"
> +
> +
>  # Save the configure command line for later reuse.
>  cat <<EOD >config.status
>  #!/bin/sh
> diff --git a/meson.build b/meson.build
> new file mode 100644
> index 0000000..b683d70
> --- /dev/null
> +++ b/meson.build
> @@ -0,0 +1,9 @@
> +project('qemu', 'c', meson_version: '>=0.50.999')
> +
> +kconfig = import('unstable-kconfig')
> +config_host = kconfig.load(meson.current_build_dir() / 'config-host.mak')
> +
> +add_project_arguments(config_host['QEMU_CFLAGS'].split(),
> +                      language: 'c')
> +add_project_arguments(config_host['QEMU_INCLUDES'].split(),
> +                      language: 'c')
> diff --git a/scripts/ninjatool.py b/scripts/ninjatool.py
> new file mode 100644
> index 0000000..6d90919
> --- /dev/null
> +++ b/scripts/ninjatool.py
[Lots of code...]

Did you write ninjatool.py specifically for QEMU, or did you steal it
(or parts) somewhere?