[PATCH] PR debug/43325

[Dodji Seketeli]

Hello,

In this example,

int
f()
{
    int i = 42; //#1
    {
      extern int i; //#2
      return i;
    }
}

we fail to emit debug info for the (re)declaration of 'i' in #2.
The debugger subsequently fails to show 'i' as belonging to the
innermost lexical block.

The patch below allows "redeclarations" debug info when they happen
inside functions.

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

        Dodji

commit 339891ac1997036eac6897fb302f776e206e10a7
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 happens in a function.
    
    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..6f8ee95 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -18238,9 +18238,9 @@ gen_variable_die (tree decl, tree origin, dw_die_ref context_die)
 
   /* 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)
+     DIE for it again. Allow re-declarations of DECLs that are
+     inside functions, though.  */
+  if (old_die && declaration && !local_scope_p (context_die))
     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;
+    }
+  }
+}