Kbuild: use -Wdeclaration-after-statement

The kernel is moving from using `-std=gnu89` to `-std=gnu11`, permitting the use of additional C11 features such as for-loop initial declarations. One contentious aspect of C99 is that it permits mixed declarations and code, and for now at least, it seems preferable to enforce that declarations must come first. These warnings were already enabled in the kernel itself, but not for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses a separate set of CFLAGS. This patch fixes an existing violation in modpost.c, which is not reported because of the missing flag in KBUILD_USERCFLAGS: | scripts/mod/modpost.c: In function ‘match’: | scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement] | 837 | const char *endp = p + strlen(p) - 1; | | ^~~~~

Mark Rutland committed 4 years ago

Commit 4d94f911 parent 13447943 files · +6 −2Browse files

Unified · Split

3 files

Makefile +2 −1
arch/arm64/kernel/vdso32/Makefile +1 −0
scripts/mod/modpost.c +3 −1

Makefile+2−1

@@ -432,7 +432,8 @@ HOSTCXX = g++ · 431 unmodified lines
432	432	endif
433	433
434	434	export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
435		− -O2 -fomit-frame-pointer -std=gnu89
	435	+ -O2 -fomit-frame-pointer -std=gnu89 \
	436	+ -Wdeclaration-after-statement
436	437	export KBUILD_USERLDFLAGS :=
437	438
438	439	KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)

arch/arm64/kernel/vdso32/Makefile+1−0

@@ -68,6 +68,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ · 67 unmodified lines
68	68	-fno-strict-aliasing -fno-common \
69	69	-Werror-implicit-function-declaration \
70	70	-Wno-format-security \
	71	+ -Wdeclaration-after-statement \
71	72	-std=gnu89
72	73	VDSO_CFLAGS += -O2
73	74	# Some useful compiler-dependent flags from top-level Makefile

scripts/mod/modpost.c+3−1

@@ -833,8 +833,10 @@ static int match(const char sym, const char const pat[]) · 832 unmodified lines
833	833	{
834	834	const char *p;
835	835	while (*pat) {
	836	+ const char *endp;
	837	+
836	838	p = *pat++;
837		− const char *endp = p + strlen(p) - 1;
	839	+ endp = p + strlen(p) - 1;
838	840
839	841	/* "foo" */
840	842	if (p == '' && endp == '') {