Allow passing config_settings to the build backend

Resolves: https://bugzilla.redhat.com/2192581

macros.aaa-pyproject-srpm

@@ -4,4 +4,4 @@
 # this macro will cause the package with the real macro to be installed.
 # When macros.pyproject is installed, it overrides this macro.
 # Note: This needs to maintain the same set of options as the real macro.
-%pyproject_buildrequires(rRxtNwe:) echo 'pyproject-rpm-macros' && exit 0
+%pyproject_buildrequires(rRxtNwe:C:) echo 'pyproject-rpm-macros' && exit 0

macros.pyproject

@@ -26,11 +26,11 @@
 # The value is read and used by the %%pytest and %%tox macros:
 %_set_pytest_addopts %global __pytest_addopts --ignore=%{_pyproject_builddir}
 
-%pyproject_wheel() %{expand:\\\
+%pyproject_wheel(C:) %{expand:\\\
 %_set_pytest_addopts
 mkdir -p "%{_pyproject_builddir}"
 CFLAGS="${CFLAGS:-${RPM_OPT_FLAGS}}" LDFLAGS="${LDFLAGS:-${RPM_LD_FLAGS}}" TMPDIR="%{_pyproject_builddir}" \\\
-%{__python3} -Bs %{_rpmconfigdir}/redhat/pyproject_wheel.py %{_pyproject_wheeldir}
+%{__python3} -Bs %{_rpmconfigdir}/redhat/pyproject_wheel.py %{?**} %{_pyproject_wheeldir}
 }
 
 
@@ -140,7 +140,7 @@ fi
 
 
 # Note: Keep the options in sync with this macro from macros.aaa-pyproject-srpm
-%pyproject_buildrequires(rRxtNwe:) %{expand:\\\
+%pyproject_buildrequires(rRxtNwe:C:) %{expand:\\\
 %_set_pytest_addopts
 # The _auto_set_build_flags feature does not do this in %%generate_buildrequires section,
 # but we want to get an environment consistent with %%build:

pyproject-rpm-macros.spec

@@ -13,7 +13,7 @@ License:        MIT
 #   Increment Y and reset Z when new macros or features are added
 #   Increment Z when this is a bugfix or a cosmetic change
 # Dropping support for EOL Fedoras is *not* considered a breaking change
-Version:        1.8.1
+Version:        1.9.0
 Release:        1%{?dist}
 
 # Macro files
@@ -161,6 +161,10 @@ export HOSTNAME="rpmbuild"  # to speedup tox in network-less mock, see rhbz#1856
 
 
 %changelog
+* Wed May 31 2023 Maxwell G <maxwell@gtmx.me> - 1.9.0-1
+- Allow passing config_settings to the build backend.
+- Resolves: rhbz#2192581
+
 * Wed May 31 2023 Miro Hrončok <mhroncok@redhat.com> - 1.8.1-1
 - On Python older than 3.11, use tomli instead of deprecated toml
 - Fix literal %% handling in %%{pyproject_files} on RPM 4.19

pyproject_buildrequires.py

@@ -14,6 +14,7 @@ import pathlib
 import zipfile
 
 from pyproject_requirements_txt import convert_requirements_txt
+from pyproject_wheel import parse_config_settings_args
 
 
 # Some valid Python version specifiers are not supported.
@@ -67,7 +68,7 @@ def guess_reason_for_invalid_requirement(requirement_str):
 class Requirements:
     """Requirement gatherer. The macro will eventually print out output_lines."""
     def __init__(self, get_installed_version, extras=None,
-                 generate_extras=False, python3_pkgversion='3'):
+                 generate_extras=False, python3_pkgversion='3', config_settings=None):
         self.get_installed_version = get_installed_version
         self.output_lines = []
         self.extras = set()
@@ -81,6 +82,7 @@ class Requirements:
 
         self.generate_extras = generate_extras
         self.python3_pkgversion = python3_pkgversion
+        self.config_settings = config_settings
 
     def add_extras(self, *extras):
         self.extras |= set(e.strip() for e in extras)
@@ -269,7 +271,7 @@ def get_backend(requirements):
 def generate_build_requirements(backend, requirements):
     get_requires = getattr(backend, 'get_requires_for_build_wheel', None)
     if get_requires:
-        new_reqs = get_requires()
+        new_reqs = get_requires(config_settings=requirements.config_settings)
         requirements.extend(new_reqs, source='get_requires_for_build_wheel')
         requirements.check(source='get_requires_for_build_wheel')
 
@@ -303,7 +305,7 @@ def generate_run_requirements_hook(backend, requirements):
             'Use the provisional -w flag to build the wheel and parse the metadata from it, '
             'or use the -R flag not to generate runtime dependencies.'
         )
-    dir_basename = prepare_metadata('.')
+    dir_basename = prepare_metadata('.', config_settings=requirements.config_settings)
     with open(dir_basename + '/METADATA') as metadata_file:
         name, requires = package_name_and_requires_from_metadata_file(metadata_file)
         for key, req in requires.items():
@@ -327,7 +329,11 @@ def generate_run_requirements_wheel(backend, requirements, wheeldir):
     wheel = find_built_wheel(wheeldir)
     if not wheel:
         import pyproject_wheel
-        returncode = pyproject_wheel.build_wheel(wheeldir=wheeldir, stdout=sys.stderr)
+        returncode = pyproject_wheel.build_wheel(
+            wheeldir=wheeldir,
+            stdout=sys.stderr,
+            config_settings=requirements.config_settings,
+        )
         if returncode != 0:
             raise RuntimeError('Failed to build the wheel for %pyproject_buildrequires -w.')
         wheel = find_built_wheel(wheeldir)
@@ -415,7 +421,7 @@ def generate_requires(
     *, include_runtime=False, build_wheel=False, wheeldir=None, toxenv=None, extras=None,
     get_installed_version=importlib.metadata.version,  # for dep injection
     generate_extras=False, python3_pkgversion="3", requirement_files=None, use_build_system=True,
-    output,
+    output, config_settings=None,
 ):
     """Generate the BuildRequires for the project in the current directory
 
@@ -426,7 +432,8 @@ def generate_requires(
     requirements = Requirements(
         get_installed_version, extras=extras or [],
         generate_extras=generate_extras,
-        python3_pkgversion=python3_pkgversion
+        python3_pkgversion=python3_pkgversion,
+        config_settings=config_settings,
     )
 
     try:
@@ -516,6 +523,12 @@ def main(argv):
         metavar='REQUIREMENTS.TXT',
         help=('Add buildrequires from file'),
     )
+    parser.add_argument(
+        '-C',
+        dest='config_settings',
+        action='append',
+        help='Configuration settings to pass to the PEP 517 backend',
+    )
 
     args = parser.parse_args(argv)
 
@@ -550,6 +563,7 @@ def main(argv):
             requirement_files=args.requirement_files,
             use_build_system=args.use_build_system,
             output=args.output,
+            config_settings=parse_config_settings_args(args.config_settings),
         )
     except Exception:
         # Log the traceback explicitly (it's useful debug info)

pyproject_buildrequires_testcases.yaml

@@ -986,3 +986,40 @@ Self-referencing extras (maze):
     python3dist(rightdep)
     python3dist(startdep)
   result: 0
+
+config_settings_control:
+  include_runtime: false
+  config_settings:
+  pyproject.toml: |
+    [build-system]
+    build-backend = "test_backend"
+    backend-path = ["."]
+  test_backend.py: |
+    def get_requires_for_build_wheel(config_settings=None):
+        if not (config_settings is None or isinstance(config_settings, dict)):
+            raise TypeError
+        if config_settings and "test-config-setting" in config_settings:
+            return ["test-config-setting"]
+        return ["test-no-config-setting"]
+  expected: |
+    python3dist(test-no-config-setting)
+  result: 0
+
+config_settings:
+  include_runtime: false
+  config_settings:
+    test-config-setting: ""
+  pyproject.toml: |
+    [build-system]
+    build-backend = "test_backend"
+    backend-path = ["."]
+  test_backend.py: |
+    def get_requires_for_build_wheel(config_settings=None):
+        if not (config_settings is None or isinstance(config_settings, dict)):
+            raise TypeError
+        if config_settings and "test-config-setting" in config_settings:
+            return ["test-config-setting"]
+        return ["test-no-config-setting"]
+  expected: |
+    python3dist(test-config-setting)
+  result: 0

pyproject_wheel.py

@@ -1,8 +1,37 @@
+import argparse
 import sys
 import subprocess
 
 
-def build_wheel(*, wheeldir, stdout=None):
+def parse_config_settings_args(config_settings):
+    """
+    Given a list of config `KEY=VALUE` formatted config settings,
+    return a dictionary that can be passed to PEP 517 hook functions.
+    """
+    if not config_settings:
+        return config_settings
+    new_config_settings = {}
+    for arg in config_settings:
+        key, _, value = arg.partition('=')
+        new_config_settings[key] = value
+    return new_config_settings
+
+
+def get_config_settings_args(config_settings):
+    """
+    Given a dictionary of PEP 517 backend config_settings,
+    yield --config-settings args that can be passed to pip's CLI
+    """
+    if not config_settings:
+        return
+    for key, value in config_settings.items():
+        if value == '':
+            yield f'--config-settings={key}'
+        else:
+            yield f'--config-settings={key}={value}'
+
+
+def build_wheel(*, wheeldir, stdout=None, config_settings=None):
     command = (
         sys.executable,
         '-m', 'pip',
@@ -15,11 +44,26 @@ def build_wheel(*, wheeldir, stdout=None):
         '--no-clean',
         '--progress-bar', 'off',
         '--verbose',
+        *get_config_settings_args(config_settings),
         '.',
     )
     cp = subprocess.run(command, stdout=stdout)
     return cp.returncode
 
 
+def parse_args(argv=None):
+    parser = argparse.ArgumentParser(prog='%pyproject_wheel')
+    parser.add_argument('wheeldir', help=argparse.SUPPRESS)
+    parser.add_argument(
+        '-C',
+        dest='config_settings',
+        action='append',
+        help='Configuration settings to pass to the PEP 517 backend',
+    )
+    args = parser.parse_args(argv)
+    args.config_settings = parse_config_settings_args(args.config_settings)
+    return args
+
+
 if __name__ == '__main__':
-    sys.exit(build_wheel(wheeldir=sys.argv[1]))
+    sys.exit(build_wheel(**vars(parse_args())))

test_pyproject_buildrequires.py

@@ -63,6 +63,7 @@ def test_data(case_name, capfd, tmp_path, monkeypatch):
             requirement_files=requirement_files,
             use_build_system=use_build_system,
             output=output,
+            config_settings=case.get('config_settings'),
         )
     except SystemExit as e:
         assert e.code == case['result']

tests/config-settings-test.spec

@@ -0,0 +1,50 @@
+Name:           config-settings-test
+Version:        1.0.0
+Release:        1%{?dist}
+Summary:        Test config_settings support
+
+License:        MIT
+URL:            ...
+Source0:        config_settings_test_backend.py
+
+
+%description
+%{summary}.
+
+
+%prep
+%autosetup -cT
+
+cp -p %{sources} .
+
+cat <<'EOF' >config_settings.py
+"""
+This is a test package
+"""
+EOF
+
+cat <<'EOF' >pyproject.toml
+[build-system]
+build-backend = "config_settings_test_backend"
+backend-path = ["."]
+requires = ["flit-core"]
+
+[project]
+name = "config_settings"
+version = "%{version}"
+dynamic = ["description"]
+EOF
+
+
+%generate_buildrequires
+%pyproject_buildrequires -C abc=123 -C xyz=456 -C--option-with-dashes=1
+%pyproject_buildrequires -C abc=123 -C xyz=456 -C--option-with-dashes=1 -w
+
+
+%build
+%pyproject_wheel -C abc=123 -C xyz=456 -C--option-with-dashes=1
+
+
+%changelog
+* Fri May 19 2023 Maxwell G <maxwell@gtmx.me>
+- Initial package

tests/config_settings_test_backend.py

@@ -0,0 +1,31 @@
+"""
+This is a test backend for pyproject-rpm-macros' integration tests
+It is not compliant with PEP 517 and omits some required hooks.
+"""
+
+from flit_core import buildapi
+
+EXPECTED_CONFIG_SETTINGS = {"abc": "123", "xyz": "456", "--option-with-dashes": "1"}
+
+
+def _verify_config_settings(config_settings):
+    print(f"config_settings={config_settings}")
+    if config_settings != EXPECTED_CONFIG_SETTINGS:
+        raise ValueError(
+            f"{config_settings!r} does not match expected {EXPECTED_CONFIG_SETTINGS!r}"
+        )
+
+
+def build_wheel(wheel_directory, config_settings=None, metadata_directory=None):
+    _verify_config_settings(config_settings)
+    return buildapi.build_wheel(wheel_directory, None, metadata_directory)
+
+
+def get_requires_for_build_wheel(config_settings=None):
+    _verify_config_settings(config_settings)
+    return buildapi.get_requires_for_build_wheel(None)
+
+
+def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
+    _verify_config_settings(config_settings)
+    return buildapi.prepare_metadata_for_build_wheel(metadata_directory, None)

tests/tests.yml

@@ -94,6 +94,9 @@
     - escape_percentages:
         dir: .
         run: ./mocktest.sh escape_percentages
+    - config-settings-test:
+        dir: .
+        run: ./mocktest.sh config-settings-test
     required_packages:
     - mock
     - rpmdevtools