show: populate missing home-page from project-urls if possible

news/11221.feature.rst

@@ -0,0 +1,3 @@
+Display the Project-URL value under key "Home-page" in ``pip show`` when the Home-Page metadata field is not set.
+
+The Project-URL key detection is case-insensitive, and ignores any dashes and underscores.

src/pip/_internal/commands/show.py

@@ -121,6 +121,22 @@ def _get_requiring_packages(current_dist: BaseDistribution) -> Iterator[str]:
 
         metadata = dist.metadata
 
+        project_urls = metadata.get_all("Project-URL", [])
+        homepage = metadata.get("Home-page", "")
+        if not homepage:
+            # It's common that there is a "homepage" Project-URL, but Home-page
+            # remains unset (especially as PEP 621 doesn't surface the field).
+            #
+            # This logic was taken from PyPI's codebase.
+            for url in project_urls:
+                url_label, url = url.split(",", maxsplit=1)
+                normalized_label = (
+                    url_label.casefold().replace("-", "").replace("_", "").strip()
+                )
+                if normalized_label == "homepage":
+                    homepage = url.strip()
+                    break
+
         yield _PackageInfo(
             name=dist.raw_name,
             version=str(dist.version),
@@ -132,8 +148,8 @@ def _get_requiring_packages(current_dist: BaseDistribution) -> Iterator[str]:
             metadata_version=dist.metadata_version or "",
             classifiers=metadata.get_all("Classifier", []),
             summary=metadata.get("Summary", ""),
-            homepage=metadata.get("Home-page", ""),
-            project_urls=metadata.get_all("Project-URL", []),
+            homepage=homepage,
+            project_urls=project_urls,
             author=metadata.get("Author", ""),
             author_email=metadata.get("Author-email", ""),
             license=metadata.get("License", ""),

tests/functional/test_show.py

@@ -3,6 +3,8 @@
 import re
 import textwrap
 
+import pytest
+
 from pip import __version__
 from pip._internal.commands.show import search_packages_info
 from pip._internal.utils.unpacking import untar_file
@@ -387,3 +389,23 @@ def test_show_deduplicate_requirements(script: PipTestEnvironment) -> None:
     result = script.pip("show", "simple", cwd=pkg_path)
     lines = result.stdout.splitlines()
     assert "Requires: pip" in lines
+
+
+@pytest.mark.parametrize(
+    "project_url", ["Home-page", "home-page", "Homepage", "homepage"]
+)
+def test_show_populate_homepage_from_project_urls(
+    script: PipTestEnvironment, project_url: str
+) -> None:
+    pkg_path = create_test_package_with_setup(
+        script,
+        name="simple",
+        version="1.0",
+        project_urls={project_url: "https://example.com"},
+    )
+    script.run("python", "setup.py", "egg_info", expect_stderr=True, cwd=pkg_path)
+    script.environ.update({"PYTHONPATH": pkg_path})
+
+    result = script.pip("show", "simple", cwd=pkg_path)
+    lines = result.stdout.splitlines()
+    assert "Home-page: https://example.com" in lines