[RFA] New dwarf2_attribute_true_p function in dwarf2read.c (take 2)

[Joel Brobecker <brobecker@gnat.com>]

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Hello,

based on some comments made by Daniel in:

    http://sources.redhat.com/ml/gdb-patches/2004-04/msg00352.html

here is a new version of the patch. This time, I only check the flag
for the DW_AT_declaration attribute. I also took this opportunity to
rework a bit the comments. It sounds like better English to me, this
time (any suggestion always welcome, btw).

2004-04-16  Joel Brobecker  <brobecker@gnat.com>

        * dwarf2read.c (dwarf2_attribute_true_p): New function.
        (die_is_declaration): Use the function above. Add some comments.

Tested on x86-linux, no regression.

OK to apply?
-- 
Joel

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Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.146
diff -u -p -r1.146 dwarf2read.c
--- dwarf2read.c	16 Apr 2004 16:12:52 -0000	1.146
+++ dwarf2read.c	16 Apr 2004 21:11:36 -0000
@@ -732,6 +732,9 @@ static void set_cu_language (unsigned in
 static struct attribute *dwarf2_attr (struct die_info *, unsigned int,
 				      struct dwarf2_cu *);
 
+static int dwarf2_attribute_true_p (struct die_info *die, unsigned name,
+                                    struct dwarf2_cu *cu);
+
 static int die_is_declaration (struct die_info *, struct dwarf2_cu *cu);
 
 static struct die_info *die_specification (struct die_info *die,
@@ -5549,11 +5552,30 @@ dwarf2_attr (struct die_info *die, unsig
   return NULL;
 }
 
+/* Return non-zero iff the attribute NAME is defined for the given DIE,
+   and holds a non-zero value.  */
+
+static int
+dwarf2_attribute_true_p (struct die_info *die, unsigned name,
+                         struct dwarf2_cu *cu)
+{
+  struct attribute *attr = dwarf2_attr (die, name, cu);
+
+  return (attr && DW_UNSND (attr));
+}
+
 static int
 die_is_declaration (struct die_info *die, struct dwarf2_cu *cu)
 {
-  return (dwarf2_attr (die, DW_AT_declaration, cu)
-	  && ! dwarf2_attr (die, DW_AT_specification, cu));
+  /* A DIE is a declaration if it has a DW_AT_declaration attribute
+     which value is non-zero.  However, we have to be careful with
+     DIEs having a DW_AT_specification attribute, because dwarf2_attr()
+     (via dwarf2_attribute_true_p) follows this attribute.  So we may
+     end up accidently finding a declaration attribute that belongs
+     to a different DIE referenced by the specification attribute,
+     even though the given DIE does not have a declaration attribute.  */
+  return (dwarf2_attribute_true_p (die, DW_AT_declaration, cu)
+	  && dwarf2_attr (die, DW_AT_specification, cu) == NULL);
 }
 
 /* Return the die giving the specification for DIE, if there is