checks: git: add PythonPEP517WithoutRevbump

Warn when DISTUTILS_USE_PEP517 is added or removed from an
ebuild without a new revision.

This is important because PEP517 affects a package's installed
files anyway and it's important to ensure that dependencies
work correctly against it, but also because e.g. config files
or other data files might either now be installed to the wrong
location or not installed at all. Developers must inspect
the image before/after (e.g. using iwdevtools) to avoid
issues.

Fixes: #498
Signed-off-by: Sam James <sam@gentoo.org>
Signed-off-by: Arthur Zamarin <arthurzam@gentoo.org>

Author: thesamesam

src/pkgcheck/checks/git.py

@@ -171,6 +171,18 @@ def desc(self):
         return f"renamed package: {self.old} -> {self.new}"
 
 
+class PythonPEP517WithoutRevbump(results.PackageResult, results.Warning):
+    """Package has started/stopped using DISTUTILS_USE_PEP517 without revbump.
+
+    The package has started or stopped using DISTUTILS_USE_PEP517 without
+    a new revision. PEP517 affects the files installed by a package
+    and might lead to some files missing.
+
+    """
+
+    desc = "changed DISTUTILS_USE_PEP517 without new revision"
+
+
 class SrcUriChecksumChange(results.PackageResult, results.Error):
     """SRC_URI changing checksum without distfile rename."""
 
@@ -265,9 +277,12 @@ class GitPkgCommitsCheck(GentooRepoCheck, GitCommitsCheck):
             MissingMove,
             SrcUriChecksumChange,
             SuspiciousSrcUriChange,
+            PythonPEP517WithoutRevbump,
         ]
     )
 
+    python_pep517_regex = re.compile("^DISTUTILS_USE_PEP517=")
+
     # package categories that are committed with stable keywords
     allowed_direct_stable = frozenset(["acct-user", "acct-group"])
 
@@ -364,6 +379,19 @@ def modified_checks(self, pkgs, added):
         if pkg not in added and old_pkg.rdepend != new_pkg.rdepend:
             yield RdependChange(pkg=new_pkg)
 
+        if "distutils-r1" in new_pkg.inherited:
+
+            def found_pep517_lines(cmp_pkg):
+                return any(
+                    self.python_pep517_regex.match(line) for line in cmp_pkg.ebuild.text_fileobj()
+                )
+
+            found_old_pep517_line = found_pep517_lines(old_pkg)
+            found_new_pep517_line = found_pep517_lines(new_pkg)
+
+            if found_old_pep517_line ^ found_new_pep517_line:
+                yield PythonPEP517WithoutRevbump(pkg=new_pkg)
+
         old_slot, new_slot = old_pkg.slot, new_pkg.slot
         if old_slot != new_slot:
             slotmoves = (

tests/checks/test_git.py

@@ -675,6 +675,25 @@ def test_checksum_change(self):
         r = self.assertReport(self.check, self.source)
         assert r == git_mod.SrcUriChecksumChange(distfile[1], pkg=CP("cat/pkg"))
 
+    def test_python_pep517_change(self):
+        with open(pjoin(self.parent_git_repo.path, "eclass/distutils-r1.eclass"), "w") as f:
+            f.write("# Copyright 1999-2019 Gentoo Authors")
+        self.parent_git_repo.add_all("eclass: add distutils-r1")
+
+        # add pkgs to parent repo
+        self.parent_repo.create_ebuild("newcat/newpkg-1", data="inherit distutils-r1")
+        self.parent_git_repo.add_all("newcat/newpkg: initial import")
+        # pull changes to child repo
+        self.child_git_repo.run(["git", "pull", "origin", "main"])
+        # change an existing ebuild to have DISTUTILS_USE_PEP517 with no revbump
+        with open(pjoin(self.child_git_repo.path, "newcat/newpkg/newpkg-1.ebuild"), "a") as f:
+            f.write("\nDISTUTILS_USE_PEP517=setuptools\n")
+        self.child_git_repo.add_all("newcat/newpkg: use PEP517")
+        self.init_check()
+        r = self.assertReport(self.check, self.source)
+        expected = git_mod.PythonPEP517WithoutRevbump(pkg=CPV("newcat/newpkg-1"))
+        assert r == expected
+
     def test_src_uri_change(self):
         distfile = [
             "DIST",