[Bug c++/14167] New: Unneeded C++ types are output in debug info due to use of static constants

["drow at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

Take this testcase:
class Class1 {
  static const int var1 = 1;
  static const int var2 = var1;
};

class Class2 {
  static const int var1 = 1;
  static const int var2 = 1;
};

Compile it with -gdwarf-2.  Debug information for Class2 will not be emitted,
which is OK, because Class2 is unused.  Debug information for Class1 will be
emitted, because Class1::var1 is marked as used in the initializer for Class1::var2,
which causes Class1::var1 to be emitted, which causes all of Class1 to be emitted.

It gets marked used in finish_id_expression as I expected:
2581          if (TREE_CODE (decl) == VAR_DECL
2582              || TREE_CODE (decl) == PARM_DECL
2583              || TREE_CODE (decl) == RESULT_DECL)
2584            mark_used (decl);

Is the used marker necessary in integral constant-expressions?  Where else?

This is the source of about 60% of the (60k!) debug information emitted for the
"trivial" C++ program:
#include <iostream>
int main() { return 0; }

-- 
           Summary: Unneeded C++ types are output in debug info due to use
                    of static constants
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: drow at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14167