[C++ Patch] Fix some locations

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,

while working on some bugs I noticed that in a few places in decl.c we 
could do better in terms of locations within the current infrastructure, 
some simple, straightforward improvements. I'm attaching below a tiny 
first patch, more to follow, I hope.

For example, a function which could be improved in many places is 
grok_ctor_properties and, before going ahead, I'd like to ask about 
something I noticed yesterday:

  /* There can be no default arguments.  */
  for (tree arg = argtypes; arg != void_list_node; arg = TREE_CHAIN (arg))
    if (TREE_PURPOSE (arg))
      {
        TREE_PURPOSE (arg) = NULL_TREE;
        if (operator_code == POSTINCREMENT_EXPR
            || operator_code == POSTDECREMENT_EXPR)
          pedwarn (input_location, OPT_Wpedantic,
                   "%qD cannot have default arguments", decl);
        else
          {
            error ("%qD cannot have default arguments", decl);
            return false;
          }
      }

the special casing seems weird, so far I haven't been able to find 
anything in the standard about it and all the other compilers I have at 
hand (Oracle, Intel, Clang) don't seem to have it. Shall we keep it or 
not? Maybe with an additional comment explaining the rationale? The 
affected testcases would be parse/defarg11.C and g++.jason/operator.C.

Thanks, Paolo.

///////////////////

Attachment: CL_locs_3
Description: Text document

Attachment: patch_locs_3
Description: Text document