Re: [PATCH 23/24] configure: prepare for auto-generated option parsing

[Thomas Huth <thuth@redhat.com>]

On 07/10/2021 15.08, Paolo Bonzini wrote:
> Prepare the configure script and Makefile for automatically generated
> help and parsing.
> 
> Because we need to run the script to generate the full help, we
> cannot rely on the user supplying the path to a Python interpreter
> with --python; therefore, the introspection output is parsed into
> shell functions and stored in scripts/.  The converter is written
> in Python as standard for QEMU, and this commit contains a stub.

Looks like a good approach to me! I've just got two questions below...

> diff --git a/configure b/configure
> index d2f754d5d1..d979476e03 100755
> --- a/configure
> +++ b/configure
> @@ -789,6 +789,18 @@ fi
>   
>   werror=""
>   
> +. $source_path/scripts/meson-buildoptions.sh
> +
> +meson_options=
> +meson_option_parse() {
> +  meson_options="$meson_options $(_meson_option_parse "$@")"
> +  if test $? -eq 1; then
> +    echo "ERROR: unknown option $1"
> +    echo "Try '$0 --help' for more information"
> +    exit 1
> +  fi
> +}

Why the detour via this wrapper and $(_meson_option_parse) ? Couldn't you 
simply add the stuff directly to $meson_options in _meson_option_parse() ?

>   for opt do
>     optarg=$(expr "x$opt" : 'x[^=]*=\(.*\)')
>     case "$opt" in
> @@ -1548,6 +1560,8 @@ for opt do
>     ;;
>     --disable-slirp-smbd) slirp_smbd=no
>     ;;
> +  --enable-* | --disable-*) meson_option_parse "$opt" "$optarg"
> +  ;;
>     *)
>         echo "ERROR: unknown option $opt"
>         echo "Try '$0 --help' for more information"
> @@ -1802,11 +1816,9 @@ Advanced options (experts only):
>                              enable plugins via shared library loading
>     --disable-containers     don't use containers for cross-building
>     --gdb=GDB-path           gdb to use for gdbstub tests [$gdb_bin]
> -
> -Optional features, enabled with --enable-FEATURE and
> -disabled with --disable-FEATURE, default is enabled if available
> -(unless built with --without-default-features):
> -
> +EOF
> +  meson_options_help
> +cat << EOF
>     system          all system emulation targets
>     user            supported user emulation targets
>     linux-user      all linux usermode emulation targets
> @@ -4487,7 +4499,8 @@ if test "$skip_meson" = no; then
>     mv $cross config-meson.cross
>   
>     rm -rf meson-private meson-info meson-logs
> -  NINJA=$ninja $meson setup \
> +  run_meson() {
> +    NINJA=$ninja $meson setup \
>           --prefix "$prefix" \
>           --libdir "$libdir" \
>           --libexecdir "$libexecdir" \
> @@ -4532,9 +4545,9 @@ if test "$skip_meson" = no; then
>           -Dpa=$pa -Daudio_drv_list=$audio_drv_list -Dtcg_interpreter=$tcg_interpreter \
>           -Dtrace_backends=$trace_backends -Dtrace_file=$trace_file -Dlinux_aio=$linux_aio \
>           -Dnetmap=$netmap -Dvde=$vde \
> -        $cross_arg \
> -        "$PWD" "$source_path"
> -
> +        "$@" $cross_arg "$PWD" "$source_path"
> +  }
> +  eval run_meson $meson_options
>     if test "$?" -ne 0 ; then
>         error_exit "meson setup failed"
>     fi
> diff --git a/scripts/meson-buildoptions.py b/scripts/meson-buildoptions.py
> new file mode 100755
> index 0000000000..8948c296b7
> --- /dev/null
> +++ b/scripts/meson-buildoptions.py
> @@ -0,0 +1,63 @@
> +#! /usr/bin/env python3
> +
> +# Generate configure command line options handling code, based on Meson's
> +# user build options introspection data
> +#
> +# Copyright (C) 2021 Red Hat, Inc.
> +#
> +# Author: Paolo Bonzini <pbonzini@redhat.com>
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 2, or (at your option)
> +# any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <https://www.gnu.org/licenses/>.
> +
> +import json
> +import textwrap
> +import shlex
> +import sys
> +
> +def sh_print(line=""):
> +    print('  printf "%s\\n"', shlex.quote(line))
> +
> +
> +def load_options(json):
> +    json = [
> +        x
> +        for x in json
> +        if x["section"] == "user"
> +        and ":" not in x["name"]
> +        and x["name"] not in SKIP_OPTIONS
> +    ]
> +    return sorted(json, key=lambda x: x["name"])
> +
> +
> +def print_help(options):
> +    print("meson_options_help() {")
> +    sh_print()
> +    sh_print("Optional features, enabled with --enable-FEATURE and")
> +    sh_print("disabled with --disable-FEATURE, default is enabled if available")
> +    sh_print("(unless built with --without-default-features):")
> +    sh_print()
> +    print("}")
> +
> +
> +def print_parse(options):
> +    print("_meson_option_parse() {")
> +    print("  case $1 in")
> +    print("    *) return 1 ;;")
> +    print("  esac")
> +    print("}")
> +
> +
> +options = load_options(json.load(sys.stdin))

Could you maybe print a header line first, à la:

# This file is generated by meson-buildoptions.py, do not edit!

?

> +print_help(options)
> +print_parse(options)
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> new file mode 100644
> index 0000000000..3be3058a6c
> --- /dev/null
> +++ b/scripts/meson-buildoptions.sh
> @@ -0,0 +1,12 @@
> +meson_options_help() {
> +  printf "%s\n" ''
> +  printf "%s\n" 'Optional features, enabled with --enable-FEATURE and'
> +  printf "%s\n" 'disabled with --disable-FEATURE, default is enabled if available'
> +  printf "%s\n" '(unless built with --without-default-features):'
> +  printf "%s\n" ''
> +}
> +_meson_option_parse() {
> +  case $1 in
> +    *) return 1 ;;
> +  esac
> +}
> 

Tested-by: Thomas Huth <thuth@redhat.com>