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 <masahiroy@xxxxxxxxxx> Reviewed-by: Sam Ravnborg <sam@xxxxxxxxxxxx> --- usr/include/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/usr/include/Makefile b/usr/include/Makefile index 84598469e6ff..e90f5f7903bb 100644 --- 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 $@ -- 2.17.1