We need to ramp up detection of unsupported CMake build systems with
CMake 4. This will detect CMakeLists.txt files setting insufficient
cmake_minimum_required VERSION level even in project subdirectories,
putting out appropriate eqawarn message about the need to fix ${PN}.

That makes us not rely on tinderbox runs w/ unmasked cmake-4 slowly
being able to build everything up to leaf packages, and also helps
detect insufficient subproject minimums that could otherwise be masked
by USE flag choice.

Problems fixed along the way:

- Make sed case-insensitive
- CMake version range may have double- or triple-dots
- Exit after first match
	We don't want more than one version for the subsequent ver_test.
	Besides, any follow-up cmake_minimum_required call will most likely
	be conditional for some type of workarounds.

Thanks-to: Sam James <sam@gentoo.org>
Thanks-to: Ionen Wolkens <ionen@gentoo.org>
Thanks-to: Michał Górny <mgorny@gentoo.org>
Bug: https://bugs.gentoo.org/951350
Signed-off-by: Andreas Sturmlechner <asturm@gentoo.org>
---
 eclass/cmake.eclass | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/eclass/cmake.eclass b/eclass/cmake.eclass
index c97f74e8a2ed..4c91afa160d9 100644
--- a/eclass/cmake.eclass
+++ b/eclass/cmake.eclass
@@ -445,6 +445,17 @@ cmake_src_configure() {
 	# Fix xdg collision with sandbox
 	xdg_environment_reset
 
+	local file ver cmreq_isold
+	while read -d '' -r file ; do
+		ver=$(sed -ne "/cmake_minimum_required/I{s/.*\(\.\.\.*\|\s\)\([0-9.]*\)\([)]\|\s\).*$/\2/p;q}" \
+			"${file}" 2>/dev/null \
+		)
+
+		if [[ -n $ver ]] && ver_test $ver -lt "3.5"; then
+			cmreq_isold=true
+		fi
+	done < <(find "${CMAKE_USE_DIR}" -type f -iname "CMakeLists.txt" -print0)
+
 	# Prepare Gentoo override rules (set valid compiler, append CPPFLAGS etc.)
 	local build_rules=${BUILD_DIR}/gentoo_rules.cmake
 
@@ -625,6 +636,16 @@ cmake_src_configure() {
 		cmakeargs+=( -C "${CMAKE_EXTRA_CACHE_FILE}" )
 	fi
 
+	if [[ ${cmreq_isold} ]]; then
+		eqawarn "QA Notice: Compatibility with CMake < 3.5 has been removed from CMake 4,"
+		eqawarn "${CATEGORY}/${PN} will fail to build w/o a fix."
+		eqawarn "See also tracker bug #951350; check existing bug or file a new one for"
+		eqawarn "this package, and take it upstream."
+		if [[ ${EAPI} == 7 ]]; then
+			eqawarn "QA Notice: EAPI=7 detected; this package is now a prime last-rites target."
+		fi
+	fi
+
 	pushd "${BUILD_DIR}" > /dev/null || die
 	debug-print "${LINENO} ${ECLASS} ${FUNCNAME}: mycmakeargs is ${mycmakeargs_local[*]}"
 	echo "${CMAKE_BINARY}" "${cmakeargs[@]}" "${CMAKE_USE_DIR}"
-- 
2.49.0