abuild: scan for python3 version requirements

Packages installing python3 site packages for python3 in version 3.x.y
depend on python3~3.x. This automatically adds the required
dependencies.

Unit test cases have been added by reusing the `py3-foo-and-bar` test
package. However, the path of that has been renamed to contain spaces
to be extra sure the logic is safe in regrade to spaces in path
names.

abuild.in

@@ -1481,6 +1481,11 @@ trace_apk_deps() {
 		autodeps="$autodeps $i"
 	done
 
+	# python3 dependencies
+	for i in $(sort -u "$dir"/.python3-needs 2>/dev/null); do
+		autodeps="$autodeps $i"
+	done
+
 	# pkg-config depends
 	for i in $(sort -u "$dir"/.needs-pc 2>/dev/null); do
 		# first check if its provided by same apkbuild
@@ -1674,6 +1679,25 @@ scan_symlink_targets() {
 	done
 }
 
+# check if python3 site packages are installed and depend on a compatible version
+scan_python3_dependency() {
+	local controldir="$2" datadir="$3"
+	local site_pkg_dirs
+	if site_pkg_dirs="$(find "$datadir"/usr/lib/ -type d -regex '.*python3\.[0-9]\+/site-packages' -mindepth 2 -maxdepth 2 2>/dev/null)"; then
+		local pyver_count="$(echo "$site_pkg_dirs" | wc -l)"
+		if [ "$pyver_count" -gt 1 ]; then
+			error "package contains python3 modules for conflicting python3 versions"
+			exit 1
+		fi
+		local pyver="${site_pkg_dirs##*usr/lib/python}"
+		pyver="${pyver%%/*}"
+		if [ -n "$pyver" ]; then
+			echo "python3~$pyver" \
+				>> "$controldir"/.python3-needs
+		fi
+	fi
+}
+
 #find pkg-config dependencies
 scan_pkgconfig_depends() {
 	local provides_pc="$1" controldir= name= datadir=
@@ -1721,6 +1745,7 @@ create_apks() {
 			subpkgname=$name
 			scan_shared_objects "$name" "$dir" "$datadir"
 			scan_symlink_targets "$name" "$dir" "$datadir"
+			scan_python3_dependency "$name" "$dir" "$datadir"
 		done
 		for file in "$pkgbasedir"/.control.*/.provides-pc; do
 			scan_pkgconfig_depends "$file"

tests/abuild_test

@@ -16,6 +16,8 @@ init_tests \
 	abuild_checksum_duplicates \
 	abuild_subpkg_dep_leak \
 	abuild_py_providers_creation \
+	abuild_py_dependency_scan \
+	abuild_py_dependency_scan_conflict \
 	abuild_reject_init_with_improper_shebang \
 	abuild_valid_pkgnames \
 	abuild_invalid_pkgnames \
@@ -331,13 +333,32 @@ abuild_subpkg_dep_leak_body() {
 abuild_py_providers_creation_body() {
 	init_keys
 	cp -ra "$testrepo" .
-	cd testrepo/py3-foo-and-bar
+	cd testrepo/py3\ foo\ and\ bar
 	abuild rootpkg || atf_fail "abuild failed"
 	atf_check -s exit:0 \
 		-o match:"provides = py3.9:foo=1.0.0-r0" \
 		cat pkg/.control.py3-foo-and-bar/.PKGINFO
 }
 
+abuild_py_dependency_scan_body() {
+	init_keys
+	cp -ra "$testrepo" .
+	cd testrepo/py3\ foo\ and\ bar
+	abuild rootpkg || atf_fail "abuild failed"
+	atf_check -s exit:0 \
+		-o match:"depend = python3~3.9" \
+		cat pkg/.control.py3-foo-and-bar/.PKGINFO
+}
+
+abuild_py_dependency_scan_conflict_body() {
+	init_keys
+	cp -ra "$testrepo" .
+	cd testrepo/py3-conflicting-python-versions
+	atf_check -s exit:1 \
+		-e match:"ERROR.*package contains python3 modules for conflicting python3 versions" \
+		abuild rootpkg
+}
+
 abuild_reject_init_with_improper_shebang_body() {
 	mkdir invalid-initd
 	cd invalid-initd

tests/testrepo/py3-conflicting-python-versions/APKBUILD

@@ -0,0 +1,17 @@
+# Maintainer: Test user <user@example.com>
+pkgname=py3-conflicting-python-versions
+pkgver=1.0.0
+pkgrel=0
+pkgdesc="dummy package for test"
+url="https://alpinelinux.org"
+license="MIT"
+builddir="$srcdir"
+
+package() {
+	for pyver in 3.9 3.42; do
+		local sitedir="usr/lib/python$pyver/site-packages"
+		mkdir -p "$pkgdir"/$sitedir/foo
+		touch "$pkgdir"/$sitedir/foo/__init__.py
+		touch "$pkgdir"/$sitedir/bar.py
+	done
+}