Re: [PATCH] PR debug/43325

[Dodji Seketeli <dodji at redhat dot com>]

On Wed, Mar 31, 2010 at 05:21:34PM -0400, Jason Merrill wrote:
> Good point.  We don't want to emit anything for the automatic file
> scope decl of static data members.
> 
> Maybe context_die != old_die->die_parent && context_die != comp_unit_die?

I think we don't want to emit duplicates at namespace scope either e.g, 
in testsuite/g++.dg/debug/dwarf2/imported-decl-1.C:

namespace A
{
  static int var2 = 2; // <--
}

int
func ()
{
  using A::var2;
  return var2;
}

The patch below does what you propose and adds a clause to prevent the 
namespace scope case.

Tested on x86_64-unknown-linux-gnu against trunk.

        Dodji

commit 91d729647c15c042474c49e5273ce796124c12ce
Author: Dodji Seketeli <dodji@redhat.com>
Date:   Thu Mar 25 20:50:17 2010 +0100

    Fix for PR debug/43325
    
    gcc/ChangeLog:
    	PR debug/43325
    	* dwarf2out.c (gen_variable_die): Allow debug info for variable
    	re-declaration when it doesn't happen at namespace or global scope.
    
    gcc/testsuite/ChangeLog:
    	PR debug/43325
    	* g++.dg/debug/dwarf2/redeclaration-1.C: New test case.

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 84a5fe7..640439b 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -18236,11 +18236,14 @@ gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
       return;
     }
 
-  /* If the compiler emitted a definition for the DECL declaration
-     and if we already emitted a DIE for it, don't emit a second
-     DIE for it again.  */
-  if (old_die
-      && declaration)
+  /* If the compiler emitted a definition for DECL
+     and if we already emitted a DIE for it, don't
+     emit a second DIE for it again neither in the
+     same scope nor in namespace scope.  */
+  if (old_die && declaration
+      && (context_die == old_die->die_parent
+	  || context_die == comp_unit_die
+	  || context_die->die_tag == DW_TAG_namespace))
     return;
 
   /* For static data members, the declaration in the class is supposed
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/redeclaration-1.C b/gcc/testsuite/g++.dg/debug/dwarf2/redeclaration-1.C
new file mode 100644
index 0000000..8aaff8e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/redeclaration-1.C
@@ -0,0 +1,18 @@
+// Origin: PR debug/43325
+// { dg-options "-g -dA" }
+// { dg-do compile }
+
+// { dg-final { scan-assembler-times "\[^\n\r\]*\\(DIE \[^\n\r\]*DW_TAG_lexical_block\\)\[\n\r\]{1,2}\[^\n\r\]*DW_AT_low_pc\[\n\r\]{1,2}\[^\n\r\]*DW_AT_high_pc\[\n\r\]{1,2}\[^\n\r\]*\\(DIE \[^\n\r\]*DW_TAG_variable\\)\[\n\r\]{1,2}\[^\n\r\]*DW_AT_name" 2 } }
+
+namespace S
+{
+  int
+  f()
+  {
+    int i = 42;
+    {
+      extern int i;
+      return i;
+    }
+  }
+}