[gentoo-dev] [PATCH 3/7] distutils-r1.eclass: Add a QA warning for pure Python file mismatch

["Michał Górny" <mgorny@gentoo.org>]

If the package is creating at least one pure Python wheel, check whether
the baseline package contents (i.e. everything but compiled Python
modules, extensions and .dist-info) match between implementations.
This is meant to ensure that we can safely optimize builds by reusing
pure Python wheels from previous builds.

Signed-off-by: Michał Górny <mgorny@gentoo.org>
---
 eclass/distutils-r1.eclass | 40 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/eclass/distutils-r1.eclass b/eclass/distutils-r1.eclass
index 89223b248157..f014a184885a 100644
--- a/eclass/distutils-r1.eclass
+++ b/eclass/distutils-r1.eclass
@@ -2021,6 +2021,44 @@ distutils-r1_src_configure() {
 	return ${ret}
 }
 
+# @FUNCTION: _distutils-r1_compare_installed_files
+# @INTERNAL
+# @DESCRIPTION:
+# Verify the the match between files installed between this and previous
+# implementation.
+_distutils-r1_compare_installed_files() {
+	debug-print-function ${FUNCNAME} "${@}"
+
+	# QA check requires diff(1).
+	if ! type -P diff &>/dev/null; then
+		return
+	fi
+
+	# Perform the check only if at least one potentially reusable wheel
+	# has been produced.  Nonpure packages (e.g. NumPy) may install
+	# interpreter configuration details into sitedir.
+	if [[ ${DISTUTILS_WHEELS[*]} != *-none-any.whl* &&
+			${DISTUTILS_WHEELS[*]} != *-abi3-*.whl ]]; then
+		return
+	fi
+
+	local sitedir=${BUILD_DIR}/install$(python_get_sitedir)
+	if [[ -n ${_DISTUTILS_PREVIOUS_SITE} ]]; then
+		diff -dur \
+			--exclude=__pycache__ \
+			--exclude='*.dist-info' \
+			--exclude="*$(get_modname)" \
+			"${_DISTUTILS_PREVIOUS_SITE}" "${sitedir}"
+		if [[ ${?} -ne 0 ]]; then
+			eqawarn "Package creating at least one pure Python wheel installs different"
+			eqawarn "Python files between implementations.  See diff in build log, above"
+			eqawarn "this message."
+		fi
+	fi
+
+	_DISTUTILS_PREVIOUS_SITE=${sitedir}
+}
+
 # @FUNCTION: _distutils-r1_post_python_compile
 # @INTERNAL
 # @DESCRIPTION:
@@ -2055,6 +2093,8 @@ _distutils-r1_post_python_compile() {
 		find "${bindir}" -type f -exec sed -i \
 			-e "1s@^#!\(${EPREFIX}/usr/bin/\(python\|pypy\)\)@#!${root}\1@" \
 			{} + || die
+
+		_distutils-r1_compare_installed_files
 	fi
 }
 
-- 
2.45.1