fix: validate description for 0.9+ (#709)

Validating only if scikit-build-core minimum-version is 0.9+ or not
present.

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

src/scikit_build_core/build/metadata.py

@@ -37,8 +37,19 @@ def get_standard_metadata(
         new_pyproject_dict["project"]["dynamic"].remove(field)
 
     metadata = StandardMetadata.from_pyproject(new_pyproject_dict)
+
     # pyproject-metadata normalizes the name - see https://github.com/FFY00/python-pyproject-metadata/pull/65
     # For scikit-build-core 0.5+, we keep the un-normalized name, and normalize it when using it for filenames
     if settings.minimum_version is None or settings.minimum_version >= Version("0.5"):
         metadata.name = new_pyproject_dict["project"]["name"]
+
+    # The description field is required to be one line. Instead of merging it
+    # or cutting off subsequent lines (setuptools), we throw a nice error.
+    # But we didn't validate before 0.9.
+    if (
+        settings.minimum_version is None or settings.minimum_version >= Version("0.9")
+    ) and "\n" in (metadata.description or ""):
+        msg = "Multiple lines in project.description are not supported; this is supposed to be a one line summary"
+        raise ValueError(msg)
+
     return metadata

tests/test_prepare_metadata.py

@@ -5,11 +5,14 @@
 from pathlib import Path
 
 import pytest
+from packaging.version import Version
 
 from scikit_build_core.build import (
     prepare_metadata_for_build_editable,
     prepare_metadata_for_build_wheel,
 )
+from scikit_build_core.build.metadata import get_standard_metadata
+from scikit_build_core.settings.skbuild_model import ScikitBuildSettings
 
 
 @pytest.mark.usefixtures("package_simplest_c")
@@ -41,3 +44,36 @@ def test_prepare_metadata_for_build(fp, editable):
 
     assert len(list(Path("simple/simplest-0.0.1.dist-info").iterdir())) == 3
     assert len(list(Path("simple").iterdir())) == 1
+
+
+def test_multiline_description():
+    with pytest.raises(ValueError, match="one line summary"):
+        get_standard_metadata(
+            pyproject_dict={
+                "project": {
+                    "name": "hello",
+                    "version": "1.1.1",
+                    "description": "One\nTwo",
+                }
+            },
+            settings=ScikitBuildSettings(),
+        )
+
+    with pytest.raises(ValueError, match="one line summary"):
+        get_standard_metadata(
+            pyproject_dict={
+                "project": {
+                    "name": "hello",
+                    "version": "1.1.1",
+                    "description": "One\nTwo",
+                }
+            },
+            settings=ScikitBuildSettings(minimum_version=Version("0.9")),
+        )
+
+    get_standard_metadata(
+        pyproject_dict={
+            "project": {"name": "hello", "version": "1.1.1", "description": "One\nTwo"}
+        },
+        settings=ScikitBuildSettings(minimum_version=Version("0.8")),
+    )