kbuild: detect missing include guard for exported headers

Adding an include guard to every header file is good practice in case it is included multiple times. Exported headers are compile-tested for the comprehensive sanity checks. Let's include the same header twice. If an include guard is missing, the header will fail to build due to redefinition of something. Signed-off-by: Masahiro Yamada <[email protected]> Reviewed-by: Sam Ravnborg <[email protected]>
fracktal · Jan 6, 2020 · 5511978 · 5511978
1 parent c79f46a
commit 5511978
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/usr/include/Makefile b/usr/include/Makefile
@@ -93,10 +93,11 @@ header-test- += asm-generic/%
 
 extra-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h' 2>/dev/null))
 
+# Include the header to detect missing include guard.
 quiet_cmd_hdrtest = HDRTEST $<
       cmd_hdrtest = \
 		$(CC) $(c_flags) -S -o /dev/null -x c /dev/null \
-			$(if $(filter-out $(header-test-), $*.h), -include $<); \
+			$(if $(filter-out $(header-test-), $*.h), -include $< -include $<); \
 		$(PERL) $(srctree)/scripts/headers_check.pl $(obj) $(SRCARCH) $<; \
 		touch $@