in case infer-version finds neither the config section, nor the requirement - skip action

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## v9.0.2
+
+### Fixed
+
+- fix #1184: in case setuptools-scm is a indirect dependency and no pyproject.toml section exists - don't infer the version
+
 
 ## v9.0.1
 

src/setuptools_scm/_config.py

@@ -272,6 +272,7 @@ def from_file(
         dist_name: str | None = None,
         missing_file_ok: bool = False,
         missing_section_ok: bool = False,
+        pyproject_data: PyProjectData | None = None,
         **kwargs: Any,
     ) -> Configuration:
         """
@@ -291,9 +292,10 @@ def from_file(
         """
 
         try:
-            pyproject_data = _read_pyproject(
-                Path(name), missing_section_ok=missing_section_ok
-            )
+            if pyproject_data is None:
+                pyproject_data = _read_pyproject(
+                    Path(name), missing_section_ok=missing_section_ok
+                )
         except FileNotFoundError:
             if missing_file_ok:
                 log.warning("File %s not found, using empty configuration", name)
@@ -303,6 +305,7 @@ def from_file(
                     project={},
                     section={},
                     is_required=False,
+                    section_present=False,
                 )
             else:
                 raise

src/setuptools_scm/_integration/pyproject_reading.py

@@ -22,6 +22,7 @@ class PyProjectData(NamedTuple):
     project: TOML_RESULT
     section: TOML_RESULT
     is_required: bool
+    section_present: bool
 
     @property
     def project_name(self) -> str | None:
@@ -55,6 +56,7 @@ def read_pyproject(
 
     try:
         section = defn.get("tool", {})[tool_name]
+        section_present = True
     except LookupError as e:
         if not is_required and not missing_section_ok:
             # Enhanced error message that mentions both configuration options
@@ -69,9 +71,12 @@ def read_pyproject(
             error = f"{path} does not contain a tool.{tool_name} section"
             log.warning("toml section missing %r", error, exc_info=True)
             section = {}
+            section_present = False
 
     project = defn.get("project", {})
-    return PyProjectData(path, tool_name, project, section, is_required)
+    return PyProjectData(
+        path, tool_name, project, section, is_required, section_present
+    )
 
 
 def get_args_for_pyproject(

src/setuptools_scm/_integration/setuptools.py

@@ -4,6 +4,7 @@
 import os
 import warnings
 
+from pathlib import Path
 from typing import Any
 from typing import Callable
 
@@ -149,8 +150,21 @@ def infer_version(dist: setuptools.Distribution) -> None:
     if dist_name == "setuptools-scm":
         return
 
+    # Check if setuptools-scm is configured before proceeding
     try:
-        config = _config.Configuration.from_file(dist_name=dist_name)
+        from .pyproject_reading import read_pyproject
+
+        pyproject_data = read_pyproject(Path("pyproject.toml"), missing_section_ok=True)
+        # Only proceed if setuptools-scm is either in build_requires or has a tool section
+        if not pyproject_data.is_required and not pyproject_data.section_present:
+            return  # No setuptools-scm configuration, silently return
+    except (FileNotFoundError, LookupError):
+        return  # No pyproject.toml or other issues, silently return
+
+    try:
+        config = _config.Configuration.from_file(
+            dist_name=dist_name, pyproject_data=pyproject_data
+        )
     except LookupError as e:
         log.info(e, exc_info=True)
     else:

testing/test_integration.py

@@ -923,6 +923,125 @@ def test_integration_function_call_order(
     )
 
 
+def test_infer_version_with_build_requires_no_tool_section(
+    wd: WorkDir, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Test that infer_version works when setuptools-scm is in build_requires but no [tool.setuptools_scm] section"""
+    if sys.version_info < (3, 11):
+        pytest.importorskip("tomli")
+
+    # Set up a git repository with a tag
+    wd.commit_testfile("test")
+    wd("git tag 1.0.0")
+    monkeypatch.chdir(wd.cwd)
+
+    # Create a pyproject.toml file with setuptools_scm in build-system.requires but NO [tool.setuptools_scm] section
+    pyproject_content = """
+[build-system]
+requires = ["setuptools>=80", "setuptools_scm>=8"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "test-package-infer-version"
+dynamic = ["version"]
+"""
+    wd.write("pyproject.toml", pyproject_content)
+
+    import setuptools
+
+    from setuptools_scm._integration.setuptools import infer_version
+
+    # Create distribution
+    dist = setuptools.Distribution({"name": "test-package-infer-version"})
+
+    # Call infer_version - this should work because setuptools_scm is in build-system.requires
+    infer_version(dist)
+
+    # Verify that version was set
+    assert dist.metadata.version is not None
+    assert dist.metadata.version == "1.0.0"
+
+    # Verify that the marker was set
+    assert getattr(dist, "_setuptools_scm_version_set_by_infer", False) is True
+
+
+def test_infer_version_with_build_requires_dash_variant_no_tool_section(
+    wd: WorkDir, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Test that infer_version works when setuptools-scm (dash variant) is in build_requires but no [tool.setuptools_scm] section"""
+    if sys.version_info < (3, 11):
+        pytest.importorskip("tomli")
+
+    # Set up a git repository with a tag
+    wd.commit_testfile("test")
+    wd("git tag 1.0.0")
+    monkeypatch.chdir(wd.cwd)
+
+    # Create a pyproject.toml file with setuptools-scm (dash variant) in build-system.requires but NO [tool.setuptools_scm] section
+    pyproject_content = """
+[build-system]
+requires = ["setuptools>=80", "setuptools-scm>=8"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "test-package-infer-version-dash"
+dynamic = ["version"]
+"""
+    wd.write("pyproject.toml", pyproject_content)
+
+    import setuptools
+
+    from setuptools_scm._integration.setuptools import infer_version
+
+    # Create distribution
+    dist = setuptools.Distribution({"name": "test-package-infer-version-dash"})
+
+    # Call infer_version - this should work because setuptools-scm is in build-system.requires
+    infer_version(dist)
+
+    # Verify that version was set
+    assert dist.metadata.version is not None
+    assert dist.metadata.version == "1.0.0"
+
+    # Verify that the marker was set
+    assert getattr(dist, "_setuptools_scm_version_set_by_infer", False) is True
+
+
+def test_infer_version_without_build_requires_no_tool_section_silently_returns(
+    wd: WorkDir, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Test that infer_version silently returns when setuptools-scm is NOT in build_requires and no [tool.setuptools_scm] section"""
+    if sys.version_info < (3, 11):
+        pytest.importorskip("tomli")
+
+    # Set up a git repository with a tag
+    wd.commit_testfile("test")
+    wd("git tag 1.0.0")
+    monkeypatch.chdir(wd.cwd)
+
+    # Create a pyproject.toml file WITHOUT setuptools_scm in build-system.requires and NO [tool.setuptools_scm] section
+    pyproject_content = """
+[build-system]
+requires = ["setuptools>=80", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "test-package-no-scm"
+dynamic = ["version"]
+"""
+    wd.write("pyproject.toml", pyproject_content)
+
+    import setuptools
+
+    from setuptools_scm._integration.setuptools import infer_version
+
+    # Create distribution
+    dist = setuptools.Distribution({"name": "test-package-no-scm"})
+
+    infer_version(dist)
+    assert dist.metadata.version is None
+
+
 def test_version_keyword_no_scm_dependency_works(
     wd: WorkDir, monkeypatch: pytest.MonkeyPatch
 ) -> None: