Perl script for de-obfuscating C++ error messages

If you've compiled C++, you've probably seen something like this:
std::_Rb_tree<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const, SystemData>,
std::_Select1st<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const,
SystemData> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >,
std::allocator<std::pair<std::basic_string<char, std::char_traits<char>, std::allocator<char> > const,
SystemData> > >::find(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const








If you stretched that out end-to-end, it would encircle the earth...
Now, "true" C++ programmers will tell you that they filter all the junk out
automatically and just see the basics of what's being said, i.e. something
about a find routine.  But if you're like me you don't do it that quickly.
In fact, you probably waste valuable time wading through all those template
parameters.  There is nothing fancy about the script, and "true" Perl
programmers will probably chuckle and do the same thing in a one-liner.
But when I couldn't figure it out by myself, I thought a bunch of other
people might not be able to figure it out either.  So I posted it below:








#!/usr/bin/perl

while(<>)
{
    # Strip out all angled bracket pairs
    while (/[<>]/)
    {
	s/<[^<>]*>//g;
    }
}










The result of the script is quite simple to understand:







_Rb_tree::find(basic_string const&) const









It's something about finding a string in a map of strings.  Of course there's no
such thing as a map of strings (maps are made up of pairs) but combined with the line numbers most compilers
emit during error messages, it should clue you in that something about a
map which you are using is messed up.  Note that this message was emitted by
the GCC compiler, which implements maps using red-black trees (_Rb_tree).  Your
compiler may say something different, but at least now you'll be able to strip
out all the template parameters.



			    


Thanks to the people who told me how to do this:

    

  • Wolfgang Bangerth
    • 

  • Bill Barth
    • 

  • Damien Warman
    • 
















 Update suggested by John Saalwaechter: The script above has two
deficiencies:

    
  
  1. 
   It has no print statement. 
  
    2. 
  
  2. 
    It fails whenever pairs of angle brackets occur without
    a matched pair, e.g. std::cout << "Hello World.";
  
    3. 


The following corrected version suggested by John Saalwaechter
fixes the problem.







#!/usr/bin/perl

while(<>)
{
    1 while s/<[^<>]*>//g;
    print;
}