[RFA] Avoid segfault in decode_line_2

[Michal Ludvig <mludvig@suse.cz>]

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Hi all,
this patch fixes a problem that I met while debugging a testsuite 
failure on amd64:

 > Running gdb-head/gdb/testsuite/gdb.c++/templates.exp ...
 > FAIL: gdb.c++/templates.exp: constructor breakpoint (timeout)

(gdb) break T5<int>::T5
-> Segfault in linespec.c:486 [decode_line_2()] because
    values.sals[i].symtab is NULL and dereferencing of
    values.sals[i].symtab->filename crashes.

After some investigation I found out that .debug_line section of the 
input file was broken (reported to binutils@ list).
However broken debug info is not an excuse for GDB to crash.

OK to apply to head and branch?

Michal Ludvig
-- 
* SuSE CR, s.r.o     * mludvig@suse.cz
* (+420) 296.545.373 * http://www.suse.cz

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2003-07-11  Michal Ludvig  <mludvig@suse.cz>

	* linespec.c (decode_line_2): Avoid crash if 
	find_function_start_sal() returns empty record.

Index: linespec.c
===================================================================
RCS file: /cvs/src/src/gdb/linespec.c,v
retrieving revision 1.49
diff -u -p -r1.49 linespec.c
--- linespec.c	8 Jun 2003 18:27:13 -0000	1.49
+++ linespec.c	11 Jul 2003 06:59:01 -0000
@@ -483,11 +483,16 @@ decode_line_2 (struct symbol *sym_arr[],
       if (sym_arr[i] && SYMBOL_CLASS (sym_arr[i]) == LOC_BLOCK)
 	{
 	  values.sals[i] = find_function_start_sal (sym_arr[i], funfirstline);
-	  printf_unfiltered ("[%d] %s at %s:%d\n",
+	  printf_unfiltered ("[%d] %s at %s:%d ",
 			     (i + 2),
 			     SYMBOL_PRINT_NAME (sym_arr[i]),
-			     values.sals[i].symtab->filename,
+			     values.sals[i].symtab ? 
+			       values.sals[i].symtab->filename :
+			       "?FILE",
 			     values.sals[i].line);
+	  if (! values.sals[i].symtab)
+	    printf_unfiltered ("[No symtab? Probably a broken debug info...]" );
+	  printf_unfiltered ("\n");
 	}
       else
 	printf_unfiltered ("?HERE\n");