[PATCH v2] kbuild: add GCC stability warning

[Samuel Rowberry <sprowdev@gmail.com>]

Newer GCC versions are not fully compatible with the code.
Adding a warning lets users know without getting in the way
of setups where it is okay to use GCC 15 (or is needed.)

Signed-off-by: Samuel Rowberry <sprowdev@gmail.com>
---
v2:
 - Fixed line wrapping in commit desc

 Makefile | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Makefile b/Makefile
index 02902bcae..361b5a509 100644
--- a/Makefile
+++ b/Makefile
@@ -720,6 +720,19 @@ endif
 
 export KBUILD_MODULES KBUILD_BUILTIN
 
+# Version check on demand because configs can get stale
+# This check is GCC-only because that is standard
+# and if someone is using a custom setup, then it is
+# assumed that their setup works.
+ifeq ($(KBUILD_BUILTIN)$(KBUILD_MODULES),11)
+ifneq ($(findstring GCC,$(CC_VERSION_TEXT)),)
+CURRENT_CC_VERSION := $(shell $(CC) -dumpversion | cut -d. -f1)
+ifeq ($(shell expr $(CURRENT_CC_VERSION) \>= 15),1)
+$(warning "GCC $(CURRENT_CC_VERSION) detected. Please use GCC 11, 12, or 13 for stability.")
+endif
+endif
+endif
+
 ifdef need-config
 include include/config/auto.conf
 endif
-- 
2.53.0