[C++ Patch/RFC] Emit DW_TAG_imported_declaration under the right class for 'using' statements in a class

[Siva Chandra]

Hi,

The attached patch fixes what seems to me as a bug in emitting a
DW_TAG_imported_declaration corresponding to 'using' statements in a
class.

Consider the following:

class A
{
 public:
  int a;
  int method (int i);
};

int
A::method (int i)
{
  return i + a;
}

class B : public A
{
 public:
  using A::method;
  int method (const B &b);
};

int
B::method (const B &b)
{
  return b.a + a;
}

Before the patch, the die corresponding to the 'using' statement in
class B was getting emitted as a child of the die corresponding to
class A.

ChangeLog:
2014-03-12  Siva Chandra Reddy  <sivachan...@google.com>

        cp/
        * class.c (handle_using_decl): Pass the correct scope to
        cp_emit_debug_info_for_using.

        testsuite/
        * g++.dg/debug/dwarf2/imported-decl-2.C: New testcase.

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index b46391b..6ad82d7 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -1299,7 +1299,7 @@ handle_using_decl (tree using_decl, tree t)
        old_value = NULL_TREE;
     }
 
-  cp_emit_debug_info_for_using (decl, USING_DECL_SCOPE (using_decl));
+  cp_emit_debug_info_for_using (decl, t);
 
   if (is_overloaded_fn (decl))
     flist = decl;
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/imported-decl-2.C 
b/gcc/testsuite/g++.dg/debug/dwarf2/imported-decl-2.C
new file mode 100644
index 0000000..70200ec
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/imported-decl-2.C
@@ -0,0 +1,32 @@
+// { dg-do compile }
+// { dg-options "-gdwarf-2 -dA -O0 -fno-merge-debug-strings" }
+
+class AAAA
+{
+ public:
+  int method (void);
+  int a;
+};
+
+int
+AAAA::method (void)
+{
+  return a;
+}
+
+class BBBB : public AAAA
+{
+ public:
+  using AAAA::method;
+
+  int method (int b);
+};
+
+int
+BBBB::method (int b)
+{
+  return a + b;
+}
+
+// { dg-final { scan-assembler-not "ascii \"BBBB\\\\0\".*ascii 
\"AAAA\\\\0\".*DW_TAG_imported_declaration" } }
+// { dg-final { scan-assembler-times "ascii \"AAAA\\\\0\".*ascii 
\"BBBB\\\\0\".*DW_TAG_imported_declaration" 1 } }