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

[René Rivera]

Duplicate of #977.