[rfa] delete 'force_return' from lookup_symbol_aux_minsyms

[David Carlton <carlton@math.stanford.edu>]

This patch is a short one: it deletes the 'force_return' argument of
lookup_symbol_aux_minsyms.  That argument was there because, when the
code in lookup_symbol_aux_minsyms was part of lookup_symbol_aux, the
return statements would sometimes cause lookup_symbol_aux to return a
NULL value without checking the psymtabs first.

I don't think that behavior was either intentional or desirable.
There's not much rhyme or reason to when this happens: in particular,
it doesn't happen every time lookup_symbol_aux_minsyms finds a minsym.
Instead, it is necessary, in addition, either for there to be a symtab at
the appropriate address or for the symtab to be NULL but for the
following test to hold:

          else if (MSYMBOL_TYPE (msymbol) != mst_text
                   && MSYMBOL_TYPE (msymbol) != mst_file_text
                   && !STREQ (name, SYMBOL_NAME (msymbol)))

(I actually experimented with trying to have lookup_symbol _always_
return NULL if a minsym was found without a corresponding symbol, and
that breaks GDB.)  I can't imagine that there are callers of
lookup_symbol that depend on having it return NULL in these particular
circumstances; it's certainly not documented anywhere.  And I suspect
that this issue is what caused the #ifdef HPUXHPPA to be added to
lookup_symbol_aux: as a relevant comment says,

  For HP-generated symbol tables, this check was causing a premature
  exit from lookup_symbol with NULL return, and thus messing up symbol
  lookups of things like "c::f".

When I asked about this issue earlier, Jim Blandy came to more or less
the same conclusion, I think: see
<http://sources.redhat.com/ml/gdb/2002-11/msg00045.html>.

David Carlton
carlton@math.stanford.edu

2002-12-05  David Carlton  <carlton@math.stanford.edu>

	* symtab.c (lookup_symbol_aux): Delete 'force_return' variable.
	(lookup_symbol_aux_minsyms): Delete 'force_return' argument.

Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.81
diff -u -p -r1.81 symtab.c
--- symtab.c	5 Dec 2002 21:26:57 -0000	1.81
+++ symtab.c	5 Dec 2002 22:23:55 -0000
@@ -117,8 +117,7 @@ struct symbol *lookup_symbol_aux_minsyms
 					  const char *mangled_name,
 					  const namespace_enum namespace,
 					  int *is_a_field_of_this,
-					  struct symtab **symtab,
-					  int *force_return);
+					  struct symtab **symtab);
 
 static struct symbol *find_active_alias (struct symbol *sym, CORE_ADDR addr);
 
@@ -805,14 +804,6 @@ lookup_symbol_aux (const char *name, con
   struct symbol *sym;
   const struct block *static_block;
 
-  /* FIXME: carlton/2002-11-05: This variable is here so that
-     lookup_symbol_aux will sometimes return NULL after receiving a
-     NULL return value from lookup_symbol_aux_minsyms, without
-     proceeding on to the partial symtab and static variable tests.  I
-     suspect that that's a bad idea.  */
-  
-  int force_return;
-
   /* Search specified block and its superiors.  Don't search
      STATIC_BLOCK or GLOBAL_BLOCK.  */
 
@@ -931,13 +922,11 @@ lookup_symbol_aux (const char *name, con
      a mangled variable that is stored in one of the minimal symbol tables.
      Eventually, all global symbols might be resolved in this way.  */
 
-  force_return = 0;
-
   sym = lookup_symbol_aux_minsyms (name, mangled_name,
 				   namespace, is_a_field_of_this,
-				   symtab, &force_return);
+				   symtab);
   
-  if (sym != NULL || force_return == 1)
+  if (sym != NULL)
     return sym;
 
 #endif
@@ -981,13 +970,11 @@ lookup_symbol_aux (const char *name, con
    */
 
 
-  force_return = 0;
-
   sym = lookup_symbol_aux_minsyms (name, mangled_name,
 				   namespace, is_a_field_of_this,
-				   symtab, &force_return);
+				   symtab);
   
-  if (sym != NULL || force_return == 1)
+  if (sym != NULL)
     return sym;
 
 #endif
@@ -1172,13 +1159,20 @@ lookup_symbol_aux_psymtabs (int block_in
    tables.  Eventually, all global symbols might be resolved in this
    way.  */
 
+/* NOTE: carlton/2002-12-05: At one point, this function was part of
+   lookup_symbol_aux, and what are now 'return' statements within
+   lookup_symbol_aux_minsyms returned from lookup_symbol_aux, even if
+   sym was NULL.  As far as I can tell, this was basically accidental;
+   it didn't happen every time that msymbol was non-NULL, but only if
+   some additional conditions held as well, and it caused problems
+   with HP-generated symbol tables.  */
+
 static struct symbol *
 lookup_symbol_aux_minsyms (const char *name,
 			   const char *mangled_name,
 			   const namespace_enum namespace,
 			   int *is_a_field_of_this,
-			   struct symtab **symtab,
-			   int *force_return)
+			   struct symtab **symtab)
 {
   struct symbol *sym;
   struct blockvector *bv;
@@ -1271,7 +1265,6 @@ lookup_symbol_aux_minsyms (const char *n
 
 	      if (symtab != NULL && sym != NULL)
 		*symtab = s;
-	      *force_return = 1;
 	      return fixup_symbol_section (sym, s->objfile);
 	    }
 	  else if (MSYMBOL_TYPE (msymbol) != mst_text
@@ -1280,7 +1273,6 @@ lookup_symbol_aux_minsyms (const char *n
 	    {
 	      /* This is a mangled variable, look it up by its
 	         mangled name.  */
-	      *force_return = 1;
 	      return lookup_symbol_aux (SYMBOL_NAME (msymbol), mangled_name,
 					NULL, namespace, is_a_field_of_this,
 					symtab);