id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
1559,bjam fails when built with gcc4.2 and strict-aliasing enabled,Kim Barrett <kab@…>,,"Using gcc4.2.1 with boost-1.34.1 on x86 SUSE10.3, the bjam that I built
segfaults when using it to build boost. A little bit of investigation leads me
to believe that bjam may not be strict-aliasing correct. Specifically

* a debug version of bjam does not exhibit this failure. (Note that the
strict-alias analysis is not by default enabled at low optimization (-O0)
levels.)

* modifying the build.jam file to add the gcc --no-strict-aliasing option when
building a release version bjam also results in a bjam which does not exhibit
this failure. Specifically, change tools/jam/src/build.jam, in the section
    ## GCC 2.x, 3.x, 4.x
    toolset gcc gcc : ""-o "" : -D
        : -pedantic
-       [ opt --release : [ opt --symbols : -g : -s ] -O3 ]
+       [ opt --release : [ opt --symbols : -g : -s ] -O3 --no-strict-aliasing
]

Note that this modification is not appropriate as is for actual merging into
boost, because (I'm fairly sure) gcc2.x does not support the
--[no-]strict-aliasing options. And of course, it might be preferable to figure
out what is really wrong (probably in the bjam source code) and fix it there.
That would likely require a much better understanding of the bjam source base
than I presently have.

* testing

BOOST_SRC_ROOT := root of boost-1.34.1 source tree
BOOST_BUILD_ROOT := root of boost-1.34.1 build tree

- modify $BOOST_SRC_ROOT/tools/jam/src/build.sh, adding ""--symbols"" option to
the invocation of ./bootstrap/jam0 at the end of the file, in order to get
debugging symbols in the final bjam, so that we can get a useful backtrace.
Note that if ""--debug"" added instead of ""--symbols"", the failure does not
occur.

cd $BOOST_SRC_ROOT/tools/jam/src
./build.sh
cd $BOOST_SRC_ROOT
gdb ./tools/jam/src/bin.linuxx86/bjam
(gdb) run toolset=gcc \
    variant=release \
    threading=multi \
    link=shared \
    --build-dir=$BOOST_BUILD_ROOT \
    --layout=system \
    --without-graph \
    --without-program_options \
    --without-regex \
    --without-signals \
    --without-wave \
    --without-python

Works if bjam built with --no-strict-aliasing. Fails as follows if bjam built
without that option.

Program received signal SIGSEGV, Segmentation fault.
0x0804ca4c in hashitem (hp=0x80db298, data=0xbfa21734, enter=1) at hash.c:172
172             keyval = *b;
(gdb) bt
#0  0x0804ca4c in hashitem (hp=0x80db298, data=0xbfa21734, enter=1) at
hash.c:172
#1  0x080591a7 in file_info (filename=0x306000a <Address 0x306000a out of
bounds>) at filesys.c:48
#2  0x0805e2d3 in file_dirscan (dir=0x8072754 ""/usr/share/boost-build"",
func=0x805a080 <builtin_glob_back>, closure=0xbfa21860)
    at fileunix.c:212
#3  0x0805a7bc in builtin_glob (parse=0x80775b8, frame=0xbfa21a90) at
builtins.c:655
#4  0x0804aa31 in evaluate_rule (rulename=0x0, frame=0xbfa21a90) at
compile.c:1036
#5  0x0804aff7 in compile_rule (parse=0x8083be0, frame=0xbfa22544) at
compile.c:597
#6  0x08049884 in compile_append (parse=0x8083c10, frame=0xbfa22544) at
compile.c:127
#7  0x0804b146 in compile_local (parse=0x8085e90, frame=0xbfa22544) at
compile.c:481
#8  0x0804b1c4 in compile_local (parse=0x8085ec0, frame=0xbfa22544) at
compile.c:505
#9  0x080532de in parse_file (f=0x806718b ""+"", frame=0xbfa22544) at parse.c:139
#10 0x0804e5f5 in main (argc=14, argv=0xbfa22664, arg_environ=Cannot access
memory at address 0x3060012
) at jam.c:453",Bugs,closed,Boost 1.36.0,Building Boost,Boost 1.34.1,Problem,duplicate,,