Re: [PATCH] uio.c: Fix warning: 'ret' might be used uninitialized

[Vitalii Demianets]

By the way, I've found that warning while working on the older kernel with 
older gcc (ver. 3.4.4). The modern gcc (ver. 4.5.4) does not emit that 
warning no matter how hard I try. For example, it does not warn even with the 
following line in the drivers/uio/Makefile:

  ccflags-$(CONFIG_UIO) += -O2 -Wall -Wextra -Wuninitialized

In that case the actual command line looks like (from "make V=1" output):

gcc -Wp,-MD,drivers/uio/.uio.o.d  -nostdinc -isystem /usr/lib/gcc/x86_64-pc-linux-gnu/4.5.4/include -I/home/vitas/Progs/net-next/net-next/arch/x86/include -Iarch/x86/include/generated  -Iinclude -I/home/vitas/Progs/net-next/net-next/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/vitas/Progs/net-next/net-next/include/uapi -Iinclude/generated/uapi -include /home/vitas/Progs/net-next/net-next/include/linux/kconfig.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -fno-delete-null-pointer-checks -O2 -m64 -mtune=generic -mno-red-zone -mcmodel=kernel -funit-at-a-time -maccumulate-outgoing-args -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_AVX=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -Wframe-larger-than=2048 -fno-stack-protector -fno-omit-frame-pointer -fno-optimize-sibling-calls -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fconserve-stack -DCC_HAVE_ASM_GOTO -O2 -Wall -Wextra -Wuninitialized    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(uio)"  -D"KBUILD_MODNAME=KBUILD_STR(uio)" -c -o 
drivers/uio/uio.o drivers/uio/uio.c

I wander why doesn't modern gcc warn about obvious use of uninitialized 
variable. Is it some known regression in gcc?

-- 
With Best Regards,
Vitalii Demianets
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