Re: [PATCH] Use meson's detected python installation

[Paolo Bonzini <pbonzini@redhat.com>]

On 9/4/25 17:11, Peter Foley wrote:
> Relying on `python3` to be avilable in $PATH doesn't work in some build
> environments. Update the build files to use the found python binary
> explicitly.

Meson already does this, if the file is not executable.  See 
docs/devel/build-system.rst:

   Meson has a special convention for invoking Python scripts: if their
   first line is ``#! /usr/bin/env python3`` and the file is *not*
   executable, find_program() arranges to invoke the script under the
   same Python interpreter that was used to invoke Meson.  This is the
   most common and preferred way to invoke support scripts from Meson
   build files, because it automatically uses the value of configure's
   --python= option.

Using "[python, 'foo']" is only needed for scripts "where it is 
desirable to make the script executable (for example for test scripts 
that developers may want to invoke from the command line, such as 
tests/qapi-schema/test-qapi.py)".

I think the only file you touched that is executable is 
scripts/qemu-plugin-symbols.py; so your issue can be fixed without code 
changes, and with a patch that only does "chmod -x 
scripts/qemu-plugin-symbols.py".  Please correct me if I'm wrong though!

Thanks,

Paolo

> Signed-off-by: Peter Foley <pefoley@google.com>
> ---
>   block/meson.build   |  6 ++----
>   meson.build         | 10 +++++-----
>   plugins/meson.build |  2 +-
>   3 files changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/block/meson.build b/block/meson.build
> index 34b1b2a30630214959630d5543181bc82a54d2b3..67e9bee1210307ff15ca87ba0f5e7f785df15042 100644
> --- a/block/meson.build
> +++ b/block/meson.build
> @@ -139,14 +139,12 @@ if get_option('dmg').allowed()
>     endforeach
>   endif
>   
> -module_block_py = find_program('../scripts/modules/module_block.py')
>   module_block_h = custom_target('module_block.h',
>                                  output: 'module_block.h',
>                                  input: modsrc,
> -                               command: [module_block_py, '@OUTPUT0@', modsrc])
> +                               command: [python, files('../scripts/modules/module_block.py'), '@OUTPUT0@', modsrc])
>   block_ss.add(module_block_h)
>   
> -wrapper_py = find_program('../scripts/block-coroutine-wrapper.py')
>   block_gen_c = custom_target('block-gen.c',
>                               output: 'block-gen.c',
>                               input: files(
> @@ -158,7 +156,7 @@ block_gen_c = custom_target('block-gen.c',
>                                         '../include/system/block-backend-io.h',
>                                         'coroutines.h'
>                                         ),
> -                            command: [wrapper_py, '@OUTPUT@', '@INPUT@'])
> +                            command: [python, files('../scripts/block-coroutine-wrapper.py'), '@OUTPUT@', '@INPUT@'])
>   block_ss.add(block_gen_c)
>   
>   block_ss.add(files('stream.c'))
> diff --git a/meson.build b/meson.build
> index fa6186db33435c26d06dce2971a9f536250607e0..6e8baf3deb13c172eecd371ea302b1c2539048d0 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -12,8 +12,6 @@ add_test_setup('slow', exclude_suites: ['thorough'],
>   add_test_setup('thorough',
>                  env: ['G_TEST_SLOW=1', 'SPEED=thorough', 'RUST_BACKTRACE=1'])
>   
> -meson.add_postconf_script(find_program('scripts/symlink-install-tree.py'))
> -
>   ####################
>   # Global variables #
>   ####################
> @@ -76,6 +74,8 @@ have_user = have_linux_user or have_bsd_user
>   sh = find_program('sh')
>   python = import('python').find_installation()
>   
> +meson.add_postconf_script([python, 'scripts/symlink-install-tree.py'])
> +
>   cc = meson.get_compiler('c')
>   all_languages = ['c']
>   if host_os == 'windows' and add_languages('cpp', required: false, native: false)
> @@ -3474,7 +3474,7 @@ foreach target : target_dirs
>         output: config_devices_mak,
>         depfile: config_devices_mak + '.d',
>         capture: true,
> -      command: [minikconf,
> +      command: [python, minikconf,
>                   get_option('default_devices') ? '--defconfig' : '--allnoconfig',
>                   config_devices_mak, '@DEPFILE@', '@INPUT@',
>                   host_kconfig, target_kconfig])
> @@ -3545,8 +3545,8 @@ config_host_h = configure_file(output: 'config-host.h', configuration: config_ho
>   genh += config_host_h
>   
>   hxtool = find_program('scripts/hxtool')
> -shaderinclude = find_program('scripts/shaderinclude.py')
> -qapi_gen = find_program('scripts/qapi-gen.py')
> +shaderinclude = [python, 'scripts/shaderinclude.py']
> +qapi_gen = [python, 'scripts/qapi-gen.py']
>   qapi_gen_depends = [ meson.current_source_dir() / 'scripts/qapi/__init__.py',
>                        meson.current_source_dir() / 'scripts/qapi/commands.py',
>                        meson.current_source_dir() / 'scripts/qapi/common.py',
> diff --git a/plugins/meson.build b/plugins/meson.build
> index 62c991d87fcdd8bcde8edddcc73909c6133f5460..6bf72a69060414ba1b7c1857515eeceb5a2c7b7c 100644
> --- a/plugins/meson.build
> +++ b/plugins/meson.build
> @@ -6,7 +6,7 @@ qemu_plugin_symbols = configure_file(
>     input: files('../include/qemu/qemu-plugin.h'),
>     output: 'qemu-plugin.symbols',
>     capture: true,
> -  command: [files('../scripts/qemu-plugin-symbols.py'), '@INPUT@'])
> +  command: [python, files('../scripts/qemu-plugin-symbols.py'), '@INPUT@'])
>   
>   # Modules need more symbols than just those in plugins/qemu-plugins.symbols
>   if not enable_modules
> 
> ---
> base-commit: baa79455fa92984ff0f4b9ae94bed66823177a27
> change-id: 20250904-python-78ccebd0fded
> 
> Best regards,