On 24 September 2012 14:22, Peter Maydell <peter.mayd...@linaro.org> wrote: > On 23 September 2012 17:33, Blue Swirl <blauwir...@gmail.com> wrote: >> Avoid this warning: >> CC arm-softmmu/hw/arm/../arm_gic.o >> /src/qemu/hw/arm/../arm_gic.c:432:17: error: implicit truncation from >> 'unsigned int' to bitfield changes value from 4294967040 to 0 >> [-Werror,-Wconstant-conversion] >> GIC_CLEAR_PENDING(irq + i, ALL_CPU_MASK); >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> /src/qemu/hw/arm/../arm_gic_internal.h:43:62: note: expanded from: >> #define GIC_CLEAR_PENDING(irq, cm) s->irq_state[irq].pending &= ~(cm) >> ^ ~~~~~ >> >> 4294967040 is 0xffffff00 and field 'pending' is effectively 8 bits >> wide, so the masking has no effect except for avoiding the warning. > > foo &= ~SOME_FLAGS; is an entirely legitimate and common C idiom, > and I think clang is being overexuberant in warning here: we should > disable this warning instead of working around it in the code.
Also, what version of clang are you using? I don't see this warning either with MacOS X "Apple clang version 4.0 (tags/Apple/clang-421.0.60) (based on LLVM 3.1svn)" or with "Ubuntu clang version 3.0-6ubuntu3 (tags/RELEASE_30/final) (based on LLVM 3.0)". -- PMM
