trust empty requires dist with modern metadata

src/poetry/inspection/info.py

@@ -15,6 +15,8 @@
 import pkginfo
 
 from build import BuildBackendException
+from poetry.core.constraints.version import Version
+from poetry.core.factory import Factory
 from poetry.core.packages.dependency import Dependency
 from poetry.core.packages.package import Package
 from poetry.core.pyproject.toml import PyProjectTOML
@@ -23,7 +25,6 @@
 from poetry.core.version.markers import InvalidMarker
 from poetry.core.version.requirements import InvalidRequirement
 
-from poetry.factory import Factory
 from poetry.utils.helpers import extractall
 from poetry.utils.isolated_build import isolated_builder
 from poetry.utils.setup_reader import SetupReader
@@ -39,6 +40,8 @@
 
 logger = logging.getLogger(__name__)
 
+DYNAMIC_METADATA_VERSION = Version.parse("2.2")
+
 
 class PackageInfoError(ValueError):
     def __init__(self, path: Path, *reasons: BaseException | str) -> None:
@@ -216,6 +219,43 @@ def to_package(
 
         return package
 
+    @classmethod
+    def _requirements_from_distribution(
+        cls,
+        dist: pkginfo.BDist | pkginfo.SDist | pkginfo.Wheel,
+    ) -> list[str] | None:
+        """
+        Helper method to extract package requirements from a `pkginfo.Distribution`
+        instance.
+
+        :param dist: The distribution instance to extract requirements from.
+        """
+        # If the distribution lists requirements, we use those.
+        #
+        # If the distribution does not list requirements, but the metadata is new enough
+        # to specify that this is because there definitely are none: then we return an
+        # empty list.
+        #
+        # If there is a requires.txt, we use that.
+        if dist.requires_dist:
+            return list(dist.requires_dist)
+
+        if dist.metadata_version is not None:
+            metadata_version = Version.parse(dist.metadata_version)
+            if (
+                metadata_version >= DYNAMIC_METADATA_VERSION
+                and "Requires-Dist" not in dist.dynamic
+            ):
+                return []
+
+        requires = Path(dist.filename) / "requires.txt"
+        if requires.exists():
+            text = requires.read_text(encoding="utf-8")
+            requirements = parse_requires(text)
+            return requirements
+
+        return None
+
     @classmethod
     def _from_distribution(
         cls, dist: pkginfo.BDist | pkginfo.SDist | pkginfo.Wheel
@@ -226,15 +266,7 @@ def _from_distribution(
 
         :param dist: The distribution instance to parse information from.
         """
-        requirements = None
-
-        if dist.requires_dist:
-            requirements = list(dist.requires_dist)
-        else:
-            requires = Path(dist.filename) / "requires.txt"
-            if requires.exists():
-                text = requires.read_text(encoding="utf-8")
-                requirements = parse_requires(text)
+        requirements = cls._requirements_from_distribution(dist)
 
         info = cls(
             name=dist.name,

tests/fixtures/inspection/demo_no_setup_pkg_info_no_deps_dynamic/PKG-INFO

@@ -0,0 +1,11 @@
+Metadata-Version: 2.2
+Name: demo
+Version: 0.1.0
+Summary: Demo project.
+Home-page: https://github.com/demo/demo
+Author: Sébastien Eustace
+Author-email: sebastien@eustace.io
+License: MIT
+Description: UNKNOWN
+Platform: UNKNOWN
+Dynamic: Requires-Dist

tests/fixtures/inspection/demo_no_setup_pkg_info_no_deps_dynamic/pyproject.toml

@@ -0,0 +1,19 @@
+# this was copied over and modified from orjson project's pyproject.toml
+# https://github.com/ijl/orjson/blob/master/pyproject.toml
+[project]
+name = "demo"
+repository = "https://github.com/demo/demo"
+
+[build-system]
+build-backend = "maturin"
+requires = ["maturin>=0.8.1,<0.9"]
+
+[tool.maturin]
+manylinux = "off"
+sdist-include = ["Cargo.lock", "json/**/*"]
+strip = "on"
+
+[tool.black]
+line-length = 88
+target-version = ['py36', 'py37', 'py38']
+include = '\.pyi?$'

tests/fixtures/inspection/demo_no_setup_pkg_info_no_deps_for_sure/PKG-INFO

@@ -0,0 +1,10 @@
+Metadata-Version: 2.3
+Name: demo
+Version: 0.1.0
+Summary: Demo project.
+Home-page: https://github.com/demo/demo
+Author: Sébastien Eustace
+Author-email: sebastien@eustace.io
+License: MIT
+Description: UNKNOWN
+Platform: UNKNOWN

tests/fixtures/inspection/demo_no_setup_pkg_info_no_deps_for_sure/pyproject.toml

@@ -0,0 +1,19 @@
+# this was copied over and modified from orjson project's pyproject.toml
+# https://github.com/ijl/orjson/blob/master/pyproject.toml
+[project]
+name = "demo"
+repository = "https://github.com/demo/demo"
+
+[build-system]
+build-backend = "maturin"
+requires = ["maturin>=0.8.1,<0.9"]
+
+[tool.maturin]
+manylinux = "off"
+sdist-include = ["Cargo.lock", "json/**/*"]
+strip = "on"
+
+[tool.black]
+line-length = 88
+target-version = ['py36', 'py37', 'py38']
+include = '\.pyi?$'

tests/inspection/test_info.py

@@ -272,10 +272,30 @@ def test_info_from_setup_cfg(demo_setup_cfg: Path) -> None:
 
 
 def test_info_no_setup_pkg_info_no_deps(fixture_dir: FixtureDirGetter) -> None:
-    info = PackageInfo.from_directory(
-        fixture_dir("inspection") / "demo_no_setup_pkg_info_no_deps",
-        disable_build=True,
+    info = PackageInfo.from_metadata_directory(
+        fixture_dir("inspection") / "demo_no_setup_pkg_info_no_deps"
+    )
+    assert info is not None
+    assert info.name == "demo"
+    assert info.version == "0.1.0"
+    assert info.requires_dist is None
+
+
+def test_info_no_setup_pkg_info_no_deps_for_sure(fixture_dir: FixtureDirGetter) -> None:
+    info = PackageInfo.from_metadata_directory(
+        fixture_dir("inspection") / "demo_no_setup_pkg_info_no_deps_for_sure",
     )
+    assert info is not None
+    assert info.name == "demo"
+    assert info.version == "0.1.0"
+    assert info.requires_dist == []
+
+
+def test_info_no_setup_pkg_info_no_deps_dynamic(fixture_dir: FixtureDirGetter) -> None:
+    info = PackageInfo.from_metadata_directory(
+        fixture_dir("inspection") / "demo_no_setup_pkg_info_no_deps_dynamic",
+    )
+    assert info is not None
     assert info.name == "demo"
     assert info.version == "0.1.0"
     assert info.requires_dist is None