[HEADS-UP] Problem with clang in 9-stable [was: r268244 (stable/9) seems to break "sysctl hw.ncpu"]

[David Chisnall]

On 4 Jul 2014, at 19:18, David Wolfskill <david at catwhisker.org> wrote:

> clang -O2 -pipe  -std=gnu99 -Qunused-arguments  -fstack-protector -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wno-uninitialized -Wno-pointer-sign -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Wno-tautological-compare -Wno-unused-value -Wno-parentheses-equality -Wno-unused-function -Wno-enum-conversion  -o sysctl sysctl.o 

This compile line is turning off a lot of warnings.  In particular, -Wno-uninitialized and -Wno-parentheses-equality are likely to hide warnings that refer to real errors.  It sounds like this case was one of them - if these warnings were on then we'd have got a build failure rather than an executable that depended on undefined behaviour.

David