macro debugging info: always include space after macro name

[Jim Blandy]

gcc -gdwarf-2 -g3 emits DW_MACINFO_define entries for macros whose
replacement list contains no tokens that lack a space after the macro
name.  The Dwarf spec says:

   In the case of a "normal" (i.e., non-function-like) macro
   definition, exactly one space character should separate the name of
   the defined macro from the following definition text.

I'm not sure the patch below is the best fix, for several reasons:

- Shouldn't meeting picayune requirements of the Dwarf format be
  handled in dwarf2out?  (Although, in the absence of guarantees from
  the caller, that code would have to scan each definition to see
  whether it needed an extra space...)

- Shouldn't the Dwarf spec be relaxed to allow generators to omit the
  space when the macro's replacement list is empty?  (Although this is
  the kind of minor variation that is appropriate for user input, but
  not so welcome in machine-readable formats...)

- If the `define' member of `struct gcc_debug_hooks' really requires
  that its `text' argument be in strict Dwarf 2 form, shouldn't that
  be documented?

Anyway, I'm happy with whatever solution folks want --- changing GCC,
GDB, or the Dwarf spec.  The only thing I don't want is for GCC and
GDB to be tacitly agreeing on a form forbidden by the spec.


2002-03-18  Jim Blandy  <jimb@redhat.com>

	* cppmacro.c (cpp_macro_definition): Emit a space after the macro
	name, even if the replacement list contains no tokens, as required
	by Dwarf.

Index: gcc/cppmacro.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cppmacro.c,v
retrieving revision 1.94
diff -c -r1.94 cppmacro.c
*** gcc/cppmacro.c	2002/03/14 18:17:12	1.94
--- gcc/cppmacro.c	2002/03/18 22:34:19
***************
*** 1561,1570 ****
        *buffer++ = ')';
      }
  
    /* Expansion tokens.  */
    if (macro->count)
      {
-       *buffer++ = ' ';
        for (i = 0; i < macro->count; i++)
  	{
  	  cpp_token *token = &macro->expansion[i];
--- 1561,1573 ----
        *buffer++ = ')';
      }
  
+   /* The Dwarf spec requires a space after the macro name, even if the
+      definition is the empty string.  */
+   *buffer++ = ' ';
+ 
    /* Expansion tokens.  */
    if (macro->count)
      {
        for (i = 0; i < macro->count; i++)
  	{
  	  cpp_token *token = &macro->expansion[i];