Re: [Boost-users] [Spirit] simplified struct.cpp coredumps

On Sat, Apr 3, 2010 at 9:40 PM, philip tucker wrote:

Hello,

I have a Spirit program that fails with a segmentation fault and I can't see why.  I hope you can help.

I'm starting from a simplified version of struct.cpp, known to work.  I want to abstract the identifier grammar into its own struct and use that instead of the inline grammar for an identifier.  The problem code is attached.

What have I done wrong?

Thanks as always for your patient, expert, and helpful comments.

P.S.

I'm running boost_1_42_0 with

gcc -v: Using built-in specs. Target: i686-apple-darwin9 Configured with: /var/tmp/gcc_42/gcc_42-5574~1/src/configure --disable-checking --enable-werror --prefix=/usr --mandir=/usr/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin9 --with-gxx-include-dir=/usr/include/c++/4.0.0 --host=i686-apple-darwin9 --target=i686-apple-darwin9 Thread model: posix gcc version 4.2.1 (Apple Inc. build 5574)

on

Model Name: iMac Model Identifier:   iMac9,1 Processor Name: Intel Core 2 Duo Processor Speed:    2.66 GHz Number Of Processors:   1 Total Number Of Cores:  2 L2 Cache:   6 MB Memory: 2 GB Bus Speed:  1.07 GHz Boot ROM Version:   IM91.008D.B08 SMC Version (system):   1.44f0

P.S.S

If you want the coredump, let me know.

I cannot run it right now, not at home, but first of all, you can change the id grammar to this (will run and compile faster): template <typename Iterator> struct id_grammar : qi::grammar { id_grammar() : id_grammar::base_type(start) { using qi::int_; using qi::raw; using ascii::alpha; using ascii::alnum; start %= raw[('_' | alpha) >> *(alnum | '_' | '-')]; } qi::rule start; }; The thing that is probably causing your failure is that you id grammar instance is being destroyed when your main grammar constructor exits on this line: client::id_grammar<Iterator> id; You need to change your whole main grammar to: template <typename Iterator> struct employee_grammar : qi::grammar { employee_grammar() : employee_grammar::base_type(start) { using qi::int_; using qi::double_; using qi::lexeme; using ascii::alpha; using ascii::alnum; start %= int_ >> id >> id >> double_ ; } /*******************************************************/ qi::rule id; /*******************************************************/ qi::rule start; client::id_grammar<Iterator> id; }; Does that work? Remember, if you are creating a grammar/rule, it needs to stick around for the whole parse, just like you stuff your rule into start (a class data member), you need your grammar a class data member too that you use in your rule. (There are ways to work around that with smart pointers and other nasty things, but it is completely unnecessary and slower, ignore them, do it the above way.)