| Message ID | 20200404082734.79321-1-ldir@darbyshire-bryant.me.uk |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [OpenWrt-Devel,v1] umdns: suppress address-of-packed-member warning | expand |
Hello, On Sat, Apr 04, 2020 at 09:27:34AM +0100, Kevin Darbyshire-Bryant wrote: > dns.c:261:2: error: converting a packed ‘struct dns_question’ pointer > (alignment 1) to a ‘uint16_t’ {aka ‘short unsigned int’} pointer > (alignment 2) may result in an unaligned pointer value > [-Werror=address-of-packed-member] > > 261 | uint16_t *swap = (uint16_t *) q; > > Work around what I think is a false positive by turning the warning off. It seems that packed structures have no alignment guarantees at all (beyond the size they're packed for), so even the first member can't be used like that. So the warning looks legit?
diff --git a/package/network/services/umdns/Makefile b/package/network/services/umdns/Makefile index ffbc3fed35..7dbbea322a 100644 --- a/package/network/services/umdns/Makefile +++ b/package/network/services/umdns/Makefile @@ -8,7 +8,7 @@ include $(TOPDIR)/rules.mk PKG_NAME:=umdns -PKG_RELEASE:=1 +PKG_RELEASE:=2 PKG_SOURCE_URL=$(PROJECT_GIT)/project/mdnsd.git PKG_SOURCE_PROTO:=git @@ -30,7 +30,7 @@ define Package/umdns DEPENDS:=+libubox +libubus +libblobmsg-json endef -TARGET_CFLAGS += -I$(STAGING_DIR)/usr/include +TARGET_CFLAGS += -I$(STAGING_DIR)/usr/include -Wno-address-of-packed-member define Package/umdns/conffiles /etc/config/umdns
gcc 8 & 9 appear to be more picky with regards access alignment to packed structures, leading to this warning in dns.c: dns.c:261:2: error: converting a packed ‘struct dns_question’ pointer (alignment 1) to a ‘uint16_t’ {aka ‘short unsigned int’} pointer (alignment 2) may result in an unaligned pointer value [-Werror=address-of-packed-member] 261 | uint16_t *swap = (uint16_t *) q; Work around what I think is a false positive by turning the warning off. Not ideal, but not quite as not ideal as build failure. Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk> --- package/network/services/umdns/Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)