Re: macros/2564: 'p siginfo->si_addr' doesn't work anymore

[tromey@redhat.com]

Synopsis: 'p siginfo->si_addr' doesn't work anymore

Responsible-Changed-From-To: unassigned->tromey
Responsible-Changed-By: tromey
Responsible-Changed-When: Thu Dec 11 01:14:13 2008
Responsible-Changed-Why:
    I'll fix this.
State-Changed-From-To: open->analyzed
State-Changed-By: tromey
State-Changed-When: Thu Dec 11 01:14:13 2008
State-Changed-Why:
    Thanks for the valgrind trace.
    
    I've looked into it a bit more.  I believe the problem
    is due to yacc lookahead.  In particular, while expanding
    "si_addr", the lexer returns a NAME token for the final
    "si_addr".  Then the lexer calls finished_macro_expansion,
    which frees the expansion string; then it returns an EOF
    token.  This causes the parser to reduce the final rule,
    resulting in a call to write_exp_string, which reads
    from the freed memory.
    
    My first thought is that the simplest thing to do would
    be to make an obstack during parsing, and simply push
    all the intermediate macro expansions onto it.
    
    I suspect this is a latent bug in 6.8, but I don't know
    how to trigger it.  This example does not work, perhaps
    because the parser decides to reduce at different times
    (I didn't check that theory).

http://sourceware.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gdb&pr=2564