cleanup pyproject loading and allow cli relative roots to be specified

this also tries to address concerns by @qubidt in #691 / #702

Author: RonnyPfannschmidt

src/setuptools_scm/_cli.py

@@ -18,7 +18,10 @@ def main(args: list[str] | None = None) -> None:
 
     try:
 
-        config = Configuration.from_file(pyproject, root=opts.root)
+        config = Configuration.from_file(
+            pyproject,
+            root=(os.path.abspath(opts.root) if opts.root is not None else None),
+        )
     except (LookupError, FileNotFoundError) as ex:
         # no pyproject.toml OR no [tool.setuptools_scm]
         print(

src/setuptools_scm/_integration/__init__.py

@@ -0,0 +1,84 @@
+from __future__ import annotations
+
+import warnings
+from typing import Any
+from typing import Callable
+from typing import Dict
+from typing import NamedTuple
+from typing import TYPE_CHECKING
+
+from .setuptools import read_dist_name_from_setup_cfg
+
+if TYPE_CHECKING:
+    from typing_extensions import TypeAlias
+
+_ROOT = "root"
+TOML_RESULT: TypeAlias = Dict[str, Any]
+TOML_LOADER: TypeAlias = Callable[[str], TOML_RESULT]
+
+
+class PyProjectData(NamedTuple):
+    tool_name: str
+    project: TOML_RESULT
+    section: TOML_RESULT
+
+    @property
+    def project_name(self) -> str | None:
+        return self.project.get("name")
+
+
+def lazy_tomli_load(data: str) -> TOML_RESULT:
+    from tomli import loads
+
+    return loads(data)
+
+
+def read_pyproject(
+    name: str = "pyproject.toml",
+    tool_name: str = "setuptools_scm",
+    _load_toml: TOML_LOADER | None = None,
+) -> PyProjectData:
+    if _load_toml is None:
+        _load_toml = lazy_tomli_load
+    with open(name, encoding="UTF-8") as strm:
+        data = strm.read()
+    defn = _load_toml(data)
+    try:
+        section = defn.get("tool", {})[tool_name]
+    except LookupError as e:
+        raise LookupError(f"{name} does not contain a tool.{tool_name} section") from e
+    project = defn.get("project", {})
+    return PyProjectData(tool_name, project, section)
+
+
+def get_args_for_pyproject(
+    pyproject: PyProjectData,
+    dist_name: str | None,
+    kwargs: TOML_RESULT,
+) -> TOML_RESULT:
+    """drops problematic details and figures the distribution name"""
+    section = pyproject.section.copy()
+    kwargs = kwargs.copy()
+
+    if "dist_name" in section:
+        if dist_name is None:
+            dist_name = section.pop("dist_name")
+        else:
+            assert dist_name == section["dist_name"]
+            del section["dist_name"]
+    if dist_name is None:
+        # minimal pep 621 support for figuring the pretend keys
+        dist_name = pyproject.project_name
+    if dist_name is None:
+        dist_name = read_dist_name_from_setup_cfg()
+    if _ROOT in kwargs:
+        if kwargs[_ROOT] is None:
+            kwargs.pop(_ROOT, None)
+        elif _ROOT in section:
+            if section[_ROOT] != kwargs[_ROOT]:
+                warnings.warn(
+                    f"root {section[_ROOT]} is overridden"
+                    f" by the cli arg {kwargs[_ROOT]}"
+                )
+            section.pop("root", None)
+    return {"dist_name": dist_name, **section, **kwargs}

src/setuptools_scm/_integration/pyproject_reading.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+import os
+from typing import IO
+
+
+def read_dist_name_from_setup_cfg(
+    input: str | os.PathLike[str] | IO[str] = "setup.cfg",
+) -> str | None:
+
+    # minimal effort to read dist_name off setup.cfg metadata
+    import configparser
+
+    parser = configparser.ConfigParser()
+
+    if isinstance(input, (os.PathLike, str)):
+        parser.read([input])
+    else:
+        parser.read_file(input)
+
+    dist_name = parser.get("metadata", "name", fallback=None)
+    return dist_name

src/setuptools_scm/_integration/setuptools.py

@@ -12,6 +12,10 @@
 from typing import TYPE_CHECKING
 from typing import Union
 
+from ._integration.pyproject_reading import (
+    get_args_for_pyproject as _get_args_for_pyproject,
+)
+from ._integration.pyproject_reading import read_pyproject as _read_pyproject
 from ._version_cls import NonNormalizedVersion
 from ._version_cls import Version
 from .utils import trace
@@ -24,7 +28,6 @@
 DEFAULT_TAG_REGEX = r"^(?:[\w-]+-)?(?P<version>[vV]?\d+(?:\.\d+){0,2}[^\+]*)(?:\+.*)?$"
 DEFAULT_VERSION_SCHEME = "guess-next-dev"
 DEFAULT_LOCAL_SCHEME = "node-and-date"
-_ROOT = "root"
 
 
 def _check_tag_regex(value: str | Pattern[str] | None) -> Pattern[str]:
@@ -67,12 +70,6 @@ def _check_absolute_root(root: _t.PathT, relative_to: _t.PathT | None) -> str:
     return os.path.abspath(root)
 
 
-def _lazy_tomli_load(data: str) -> dict[str, Any]:
-    from tomli import loads
-
-    return loads(data)
-
-
 _VersionT = Union[Version, NonNormalizedVersion]
 
 
@@ -202,7 +199,7 @@ def from_file(
         cls,
         name: str = "pyproject.toml",
         dist_name: str | None = None,
-        _load_toml: Callable[[str], dict[str, Any]] = _lazy_tomli_load,
+        _load_toml: Callable[[str], dict[str, Any]] | None = None,
         **kwargs: Any,
     ) -> Configuration:
         """
@@ -212,61 +209,7 @@ def from_file(
         not contain the [tool.setuptools_scm] section.
         """
 
-        with open(name, encoding="UTF-8") as strm:
-            data = strm.read()
+        pyproject_data = _read_pyproject(name, _load_toml=_load_toml)
+        args = _get_args_for_pyproject(pyproject_data, dist_name, kwargs)
 
-        defn = _load_toml(data)
-        try:
-            section = defn.get("tool", {})["setuptools_scm"]
-        except LookupError as e:
-            raise LookupError(
-                f"{name} does not contain a tool.setuptools_scm section"
-            ) from e
-
-        project = defn.get("project", {})
-        dist_name = cls._cleanup_from_file_args_data(
-            project, dist_name, kwargs, section
-        )
-        return cls(dist_name=dist_name, relative_to=name, **section, **kwargs)
-
-    @staticmethod
-    def _cleanup_from_file_args_data(
-        project: dict[str, Any],
-        dist_name: str | None,
-        kwargs: dict[str, Any],
-        section: dict[str, Any],
-    ) -> str | None:
-        """drops problematic details and figures the distribution name"""
-        if "dist_name" in section:
-            if dist_name is None:
-                dist_name = section.pop("dist_name")
-            else:
-                assert dist_name == section["dist_name"]
-                del section["dist_name"]
-        if dist_name is None:
-            # minimal pep 621 support for figuring the pretend keys
-            dist_name = project.get("name")
-        if dist_name is None:
-            dist_name = _read_dist_name_from_setup_cfg()
-        if _ROOT in kwargs:
-            if kwargs[_ROOT] is None:
-                kwargs.pop(_ROOT, None)
-            elif _ROOT in section:
-                if section[_ROOT] != kwargs[_ROOT]:
-                    warnings.warn(
-                        f"root {section[_ROOT]} is overridden"
-                        f" by the cli arg {kwargs[_ROOT]}"
-                    )
-                section.pop("root", None)
-        return dist_name
-
-
-def _read_dist_name_from_setup_cfg() -> str | None:
-
-    # minimal effort to read dist_name off setup.cfg metadata
-    import configparser
-
-    parser = configparser.ConfigParser()
-    parser.read(["setup.cfg"])
-    dist_name = parser.get("metadata", "name", fallback=None)
-    return dist_name
+        return cls(relative_to=name, **args)

src/setuptools_scm/config.py

@@ -11,7 +11,9 @@
 from . import _get_version
 from . import _version_missing
 from ._entrypoints import iter_entry_points
-from .config import _read_dist_name_from_setup_cfg
+from ._integration.setuptools import (
+    read_dist_name_from_setup_cfg as _read_dist_name_from_setup_cfg,
+)
 from .config import Configuration
 from .utils import do
 from .utils import trace

src/setuptools_scm/integration.py

@@ -34,8 +34,11 @@ def test_cli_find_pyproject(
     out = get_output([])
     assert out.startswith("0.1.dev1+")
 
-    with pytest.raises(SystemExit, match="no version found for"):
-        get_output(["--root=.."])
+    with pytest.warns(
+        UserWarning, match="absolute root path '%s' overrides relative_to '%s'"
+    ):
+        with pytest.raises(SystemExit, match="no version found for"):
+            get_output(["--root=.."])
 
     wd.write(PYPROJECT_TOML, PYPROJECT_ROOT)
     with pytest.raises(SystemExit, match="no version found for"):