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Subject: Re: [HEADS-UP] Problem with clang in 9-stable [was: r268244
 (stable/9) seems to break "sysctl hw.ncpu"]
From: David Chisnall <theraven@theravensnest.org>
In-Reply-To: <20140704181831.GV6056@albert.catwhisker.org>
Date: Sat, 5 Jul 2014 13:49:44 +0100
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References: <20140704123901.GR6056@albert.catwhisker.org>
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To: David Wolfskill <david@catwhisker.org>
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On 4 Jul 2014, at 19:18, David Wolfskill <david@catwhisker.org> wrote:

> clang -O2 -pipe  -std=3Dgnu99 -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=20

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