On 22 Mar 2015, at 22:23, Dimitry Andric <d...@freebsd.org> wrote: > > On 22 Mar 2015, at 22:02, Craig Rodrigues <rodr...@freebsd.org> wrote: >> >> On Sun, Mar 22, 2015 at 11:26 AM, <jenkins-ad...@freebsd.org> wrote: >> >>> See <https://jenkins.freebsd.org/job/FreeBSD_HEAD-tests2/867/> >>> >> >> Can someone with toolchain expertise look at this? >> After the clang 3.6.1 import, /bin/expr behaves differently. >> >> With clang 3.5.0: >> >> # expr 4611686018427387904 + 4611686018427387904 >> expr: overflow >> >> With clang 3.6.1: >> >> # expr 4611686018427387904 + 4611686018427387904 >> -9223372036854775808 > > It works fine for me: > > $ /usr/obj/usr/src/bin/expr/expr 4611686018427387904 + 4611686018427387904 > expr: overflow
Ah right, that was on i386, on amd64 it does result in -2^63. It is indeed
caused by reliance on signed integer wrapping.
This diff should fix it, without rewriting the utility:
Index: bin/expr/Makefile
===================================================================
--- bin/expr/Makefile (revision 280156)
+++ bin/expr/Makefile (working copy)
@@ -6,6 +6,9 @@ PROG= expr
SRCS= expr.y
YFLAGS=
+# expr relies on signed integer wrapping
+CFLAGS+= -fwrapv
+
NO_WMISSING_VARIABLE_DECLARATIONS=
.if ${MK_TESTS} != "no"
-Dimitry
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