mesonpy: make pep621 a hard dependency

Signed-off-by: Filipe Laíns <lains@riseup.net>

mesonpy/__init__.py

@@ -54,7 +54,6 @@
 class _depstr:
     ninja = 'ninja >= 1.10.0'
     patchelf_wrapper = 'patchelf-wrapper'
-    pep621 = 'pep621 >= 0.3.0'
     wheel = 'wheel >= 0.36.0'  # noqa: F811
 
 
@@ -762,16 +761,6 @@ def _project(config_settings: Optional[Dict[Any, Any]]) -> Iterator[Project]:
         yield project
 
 
-def get_requires_for_build_sdist(
-    config_settings: Optional[Dict[Any, Any]] = None,
-) -> List[str]:
-    dependencies = []
-    with _project(config_settings) as project:
-        if project.pep621:
-            dependencies.append(_depstr.pep621)
-    return dependencies
-
-
 def build_sdist(
     sdist_directory: str,
     config_settings: Optional[Dict[Any, Any]] = None,
@@ -790,8 +779,6 @@ def get_requires_for_build_wheel(
     with _project(config_settings) as project:
         if not project.is_pure and platform.system() == 'Linux':
             dependencies.append(_depstr.patchelf_wrapper)
-        if project.pep621:
-            dependencies.append(_depstr.pep621)
     return dependencies
 
 

pyproject.toml

@@ -4,6 +4,7 @@ backend-path = ['.']
 requires = [
   'meson>=0.60.0',
   'ninja',
+  'pep621>=0.3.0',
   'tomli>=1.0.0',
   'typing-extensions>=3.7.4; python_version<"3.8"',
 ]
@@ -28,6 +29,7 @@ dependencies = [
   'colorama; os_name == "nt"',
   'meson>=0.60.0',
   'ninja',
+  'pep621>=0.3.0', # not a hard dependency, only needed for projects that use PEP 621 metadata
   'tomli>=1.0.0',
   'typing-extensions>=3.7.4; python_version<"3.8"',
 ]

tests/test_pep517.py

@@ -15,25 +15,11 @@
     VENDORING_DEPS = set()
 
 
-@pytest.mark.parametrize(
-    ('package', 'expected'),
-    [
-        ('pure', set()),  # no PEP 621
-        ('full-metadata', {mesonpy._depstr.pep621}),  # PEP 621
-    ]
-)
-def test_get_requires_for_build_sdist(package, expected):
-    with cd_package(package):
-        assert set(mesonpy.get_requires_for_build_sdist()) == expected
-
-
 @pytest.mark.parametrize(
     ('package', 'expected'),
     [
         ('pure', set()),  # pure and no PEP 621
-        ('full-metadata', {mesonpy._depstr.pep621}),  # pure and PEP 621
         ('library', VENDORING_DEPS),  # not pure and not PEP 621
-        ('library-pep621', {mesonpy._depstr.pep621, *VENDORING_DEPS}),  # not pure and PEP 621
     ]
 )
 def test_get_requires_for_build_wheel(package, expected):