Re: [PATCH 1/2] namespace support

[Sami Wagiaalla <swagiaal@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 14959 bytes --]

Tom Tromey wrote:
>>>>>> "Sami" == Sami Wagiaalla <swagiaal@redhat.com> writes:
> 
> Sami> Currently imports statements are stored in the nearest static
> Sami> block. Also, these import statements only correspond to the
> Sami> implicit importing of annonymous namespaces.
> 
> This looks pretty reasonable to me.
> A few nits and such...
> 
> Sami> +/* This returns the using directives list associated to BLOCK, if
> Sami> +   any.  Each BLOCK_NAMESPACE()->USING already contains all the namespaces
> Sami> +   imported at that code point - even those from its parent blocks.  */
> 
> I think the caps on "USING" here are weird.
> Maybe just:
> 
>     The result contains all the [...]

I changed it to:

/* This returns the using directives list associated with BLOCK, if
     any.  */

The second part of the comment is not correct.

> 
> Sami> +/* using directives local to lexical context */
> 
> Comments should in general be sentences -- starting with a capital
> letter and ending with a period and two spaces.
> Here I would probably write:
> 
>   /* "using" directives local to lexical context.  */
> 
> ... avoiding the capital since "using" is a keyword.
> 
> Sami> +EXTERN struct using_direct *using_directives;
> 
> Eww, buildsym is full of globals.  Not your problem :-), but yet
> another thing that would be nice to clean up.
> 

There is a nice clean up for this suggested by Jan. That is using the
variables in the current context object and automating saving/and
restoration of that. I'll post a patch if I get to it.

> 
> Sami> +static void
> Sami> +read_import_statement (struct die_info *die, struct dwarf2_cu *cu)
> 
> [...]
> 
> Sami> +  if (imported_name == NULL)
> Sami> +    {
> Sami> +      /* C++ imports from std:: DW_TAG_base_type with no DW_AT_name - why?  */
> 
> It would be nice to understand this before the patch goes in.
> 

This is a gcc bug. I filed it here:
https://bugzilla.redhat.com/show_bug.cgi?id=506524 and improved the comment.
and improved the comment.

also I changed the line above the comment to use dwarf2_name instead of
namespace_name which is incorrect.

-  imported_name = namespace_name (imported_die, &is_anonymous, cu);
+  imported_name = dwarf2_name (imported_die, cu);

> Sami> +  /* FIXME: dwarf2_name (die); for the local name after import.  */
> 
> It would also be nice if we could not add new FIXMEs.
> Or is that handled in a later patch?
> 

Yes, it will be handled in a later patch.

> Sami> +  using_directives = cp_add_using (imported_name, strlen (imported_name), 0,
> Sami> +                                   using_directives);
> Sami> +}
> 
> I didn't look -- but are there other buildsym globals which are
> actively updated by the dwarf reader like this?  I'm wondering whether
> this is something that should be hidden inside a call, like a new
> wrapper for cp_add_using.
> 

For now using_directives is a global. I wrote this to be parallel to
local_symbols. If the context clean up is done cp_add_using can just
request  the current context

> This is not a big deal.
> 
> Tom

-----------------------------------------


  2009-05-21  Sami Wagiaalla  <swagiaal@redhat.com>

	* dwarf2read.c (process_die): Handle import statements
  	(DW_TAG_imported_declaration, case DW_TAG_imported_module)
  	(read_import_statement): New.
  	(read_func_scope): Update using_directives to point to current context
  	(read_lexical_block_scope): Ditto.
  	* cp-support.h: Added prototype for cp_add_using.
  	* cp-namespace.c: Removed local context_stack.
  	(cp_initialize_namespace): Deleted.
  	(cp_finalize_namespace): Deleted.
  	(cp_add_using_directive): Use using_directives instead of using_list.
  	(cp_add_using): No longer static.
  	* buildsym.h: Created global using_direct variable.
  	Created using_direct variable in context_stack.
  	* buildsym.c (finish_block): Set using directives for the block	under
  	construction.
  	(start_symtab): Removed call to cp_initialize_namespace().
  	(end_symtab): Removed call to cp_finalize_namespace().
  	(push_context): Save and reset using_directives.
  	* block.c (block_using): Return using directives for given
  	block instead of static block.


diff --git a/gdb/block.c b/gdb/block.c
index 8f0140c..9ebe975 100644
--- a/gdb/block.c
+++ b/gdb/block.c
@@ -206,25 +206,16 @@ block_set_scope (struct block *block, const char *scope,
    BLOCK_NAMESPACE (block)->scope = scope;
  }

-/* This returns the first using directives associated to BLOCK, if
+/* This returns the using directives list associated with BLOCK, if
     any.  */

-/* FIXME: carlton/2003-04-23: This uses the fact that we currently
-   only have using directives in static blocks, because we only
-   generate using directives from anonymous namespaces.  Eventually,
-   when we support using directives everywhere, we'll want to replace
-   this by some iterator functions.  */
-
  struct using_direct *
  block_using (const struct block *block)
  {
-  const struct block *static_block = block_static_block (block);
-
-  if (static_block == NULL
-      || BLOCK_NAMESPACE (static_block) == NULL)
+  if (block == NULL || BLOCK_NAMESPACE (block) == NULL)
      return NULL;
    else
-    return BLOCK_NAMESPACE (static_block)->using;
+    return BLOCK_NAMESPACE (block)->using;
  }

  /* Set BLOCK's using member to USING; if needed, allocate memory via
diff --git a/gdb/buildsym.c b/gdb/buildsym.c
index e7c48fe..e6ef9c6 100644
--- a/gdb/buildsym.c
+++ b/gdb/buildsym.c
@@ -384,6 +384,8 @@ finish_block (struct symbol *symbol, struct pending **listhead,
        opblock = pblock;
      }

+  block_set_using (block, using_directives, &objfile->objfile_obstack);
+
    record_pending_block (objfile, block, opblock);

    return block;
@@ -812,10 +814,6 @@ start_symtab (char *name, char *dirname, CORE_ADDR start_addr)
    /* We shouldn't have any address map at this point.  */
    gdb_assert (! pending_addrmap);

-  /* Set up support for C++ namespace support, in case we need it.  */
-
-  cp_initialize_namespace ();
-
    /* Initialize the list of sub source files with one entry for this
       file (the top-level source file).  */

@@ -1012,8 +1010,6 @@ end_symtab (CORE_ADDR end_addr, struct objfile *objfile, int section)
        finish_block (0, &global_symbols, 0, last_source_start_addr, end_addr,
  		    objfile);
        blockvector = make_blockvector (objfile);
-      cp_finalize_namespace (BLOCKVECTOR_BLOCK (blockvector, STATIC_BLOCK),
-			     &objfile->objfile_obstack);
      }

    /* Read the line table if it has to be read separately.  */
@@ -1225,10 +1221,12 @@ push_context (int desc, CORE_ADDR valu)
    new->params = param_symbols;
    new->old_blocks = pending_blocks;
    new->start_addr = valu;
+  new->using_directives = using_directives;
    new->name = NULL;

    local_symbols = NULL;
    param_symbols = NULL;
+  using_directives = NULL;

    return new;
  }
diff --git a/gdb/buildsym.h b/gdb/buildsym.h
index bf23ecc..6f8b09f 100644
--- a/gdb/buildsym.h
+++ b/gdb/buildsym.h
@@ -125,6 +125,10 @@ EXTERN struct pending *local_symbols;

  EXTERN struct pending *param_symbols;

+/* "using" directives local to lexical context.  */
+
+EXTERN struct using_direct *using_directives;
+
  /* Stack representing unclosed lexical contexts (that will become
     blocks, eventually).  */

@@ -138,6 +142,10 @@ struct context_stack

      struct pending *params;

+    /* Pending using directives at the time we entered.  */
+
+    struct using_direct *using_directives;
+
      /* Pointer into blocklist as of entry */

      struct pending_block *old_blocks;
diff --git a/gdb/cp-namespace.c b/gdb/cp-namespace.c
index c6c5617..f3b2194 100644
--- a/gdb/cp-namespace.c
+++ b/gdb/cp-namespace.c
@@ -30,15 +30,7 @@
  #include "dictionary.h"
  #include "command.h"
  #include "frame.h"
-
-/* List of using directives that are active in the current file.  */
-
-static struct using_direct *using_list;
-
-static struct using_direct *cp_add_using (const char *name,
-					  unsigned int inner_len,
-					  unsigned int outer_len,
-					  struct using_direct *next);
+#include "buildsym.h"

  static struct using_direct *cp_copy_usings (struct using_direct *using,
  					    struct obstack *obstack);
@@ -78,31 +70,6 @@ static struct symbol *lookup_possible_namespace_symbol (const char *name);

  static void maintenance_cplus_namespace (char *args, int from_tty);

-/* Set up support for dealing with C++ namespace info in the current
-   symtab.  */
-
-void cp_initialize_namespace ()
-{
-  using_list = NULL;
-}
-
-/* Add all the using directives we've gathered to the current symtab.
-   STATIC_BLOCK should be the symtab's static block; OBSTACK is used
-   for allocation.  */
-
-void
-cp_finalize_namespace (struct block *static_block,
-		       struct obstack *obstack)
-{
-  if (using_list != NULL)
-    {
-      block_set_using (static_block,
-		       cp_copy_usings (using_list, obstack),
-		       obstack);
-      using_list = NULL;
-    }
-}
-
  /* Check to see if SYMBOL refers to an object contained within an
     anonymous namespace; if so, add an appropriate using directive.  */

@@ -170,7 +137,7 @@ cp_add_using_directive (const char *name, unsigned int outer_length,

    /* Has it already been added?  */

-  for (current = using_list; current != NULL; current = current->next)
+  for (current = using_directives; current != NULL; current = current->next)
      {
        if ((strncmp (current->inner, name, inner_length) == 0)
  	  && (strlen (current->inner) == inner_length)
@@ -178,8 +145,8 @@ cp_add_using_directive (const char *name, unsigned int outer_length,
  	return;
      }

-  using_list = cp_add_using (name, inner_length, outer_length,
-			     using_list);
+  using_directives = cp_add_using (name, inner_length, outer_length,
+                                   using_directives);
  }

  /* Record the namespace that the function defined by SYMBOL was
@@ -237,7 +204,7 @@ cp_is_anonymous (const char *namespace)
     using xmalloc.  It copies the strings, so NAME can be a temporary
     string.  */

-static struct using_direct *
+struct using_direct *
  cp_add_using (const char *name,
  	      unsigned int inner_len,
  	      unsigned int outer_len,
diff --git a/gdb/cp-support.h b/gdb/cp-support.h
index 837ca6c..e577f7d 100644
--- a/gdb/cp-support.h
+++ b/gdb/cp-support.h
@@ -80,6 +80,11 @@ extern void cp_add_using_directive (const char *name,
  				    unsigned int outer_length,
  				    unsigned int inner_length);

+extern struct using_direct *cp_add_using (const char *name,
+					  unsigned int inner_len,
+					  unsigned int outer_len,
+					  struct using_direct *next);
+
  extern void cp_initialize_namespace (void);

  extern void cp_finalize_namespace (struct block *static_block,
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index ae8870c..6569798 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -946,6 +946,8 @@ static void read_namespace (struct die_info *die, struct dwarf2_cu *);

  static void read_module (struct die_info *die, struct dwarf2_cu *cu);

+static void read_import_statement (struct die_info *die, struct dwarf2_cu *);
+
  static const char *namespace_name (struct die_info *die,
  				   int *is_anonymous, struct dwarf2_cu *);

@@ -2984,14 +2986,12 @@ process_die (struct die_info *die, struct dwarf2_cu *cu)
        break;
      case DW_TAG_imported_declaration:
      case DW_TAG_imported_module:
-      /* FIXME: carlton/2002-10-16: Eventually, we should use the
-	 information contained in these.  DW_TAG_imported_declaration
-	 dies shouldn't have children; DW_TAG_imported_module dies
-	 shouldn't in the C++ case, but conceivably could in the
-	 Fortran case.  */
        processing_has_namespace_info = 1;
-      complaint (&symfile_complaints, _("unsupported tag: '%s'"),
-		 dwarf_tag_name (die->tag));
+      if (die->child != NULL && (die->tag == DW_TAG_imported_declaration
+				 || cu->language != language_fortran))
+	complaint (&symfile_complaints, _("Tag '%s' has unexpected children"),
+		   dwarf_tag_name (die->tag));
+      read_import_statement (die, cu);
        break;
      default:
        new_symbol (die, NULL, cu);
@@ -3037,6 +3037,69 @@ dwarf2_full_name (struct die_info *die, struct dwarf2_cu *cu)
    return name;
  }

+/* Read the import statement specified by the given die and record it.  */
+
+static void
+read_import_statement (struct die_info *die, struct dwarf2_cu *cu)
+{
+  struct attribute *import_attr;
+  struct die_info *imported_die;
+  const char *imported_name;
+  int is_anonymous = 0;
+
+  import_attr = dwarf2_attr (die, DW_AT_import, cu);
+  if (import_attr == NULL)
+    {
+      complaint (&symfile_complaints, _("Tag '%s' has no DW_AT_import"),
+		 dwarf_tag_name (die->tag));
+      return;
+    }
+
+  imported_die = follow_die_ref (die, import_attr, &cu);
+  imported_name = dwarf2_name (imported_die, cu);
+  if (imported_name == NULL)
+    {
+      /* GCC bug: https://bugzilla.redhat.com/show_bug.cgi?id=506524
+
+        The import in the following code:
+        namespace A
+          {
+            typedef int B;
+          }
+
+        int main ()
+          {
+            using A::B;
+            B b;
+            return b;
+          }
+
+        ...
+         <2><51>: Abbrev Number: 3 (DW_TAG_imported_declaration)
+            <52>   DW_AT_decl_file   : 1
+            <53>   DW_AT_decl_line   : 6
+            <54>   DW_AT_import      : <0x75>
+         <2><58>: Abbrev Number: 4 (DW_TAG_typedef)
+            <59>   DW_AT_name        : B
+            <5b>   DW_AT_decl_file   : 1
+            <5c>   DW_AT_decl_line   : 2
+            <5d>   DW_AT_type        : <0x6e>
+        ...
+         <1><75>: Abbrev Number: 7 (DW_TAG_base_type)
+            <76>   DW_AT_byte_size   : 4
+            <77>   DW_AT_encoding    : 5        (signed)
+
+        imports the wrong die ( 0x75 instead of 0x58 ).
+        This case will be ignored until the gcc bug is fixed.  */
+      return;
+    }
+
+  /* FIXME: dwarf2_name (die); for the local name after import.  */
+
+  using_directives = cp_add_using (imported_name, strlen (imported_name), 0,
+                                   using_directives);
+}
+
  static void
  initialize_cu_func_list (struct dwarf2_cu *cu)
  {
@@ -3370,6 +3433,7 @@ read_func_scope (struct die_info *die, struct dwarf2_cu *cu)
       back to building a containing block's symbol lists.  */
    local_symbols = new->locals;
    param_symbols = new->params;
+  using_directives = new->using_directives;

    /* If we've finished processing a top-level function, subsequent
       symbols go in the file symbol list.  */
@@ -3432,6 +3496,7 @@ read_lexical_block_scope (struct die_info *die, struct dwarf2_cu *cu)
        dwarf2_record_block_ranges (die, block, baseaddr, cu);
      }
    local_symbols = new->locals;
+  using_directives = new->using_directives;
  }

  /* Get low and high pc attributes from DW_AT_ranges attribute value OFFSET.


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 2009-05-21  Sami Wagiaalla  <swagiaal@redhat.com>
 
	* dwarf2read.c (process_die): Handle import statements 
 	(DW_TAG_imported_declaration, case DW_TAG_imported_module)
 	(read_import_statement): New.
 	(read_func_scope): Update using_directives to point to current context
 	(read_lexical_block_scope): Ditto.
 	* cp-support.h: Added prototype for cp_add_using.
 	* cp-namespace.c: Removed local context_stack.
 	(cp_initialize_namespace): Deleted.
 	(cp_finalize_namespace): Deleted.
 	(cp_add_using_directive): Use using_directives instead of using_list.
 	(cp_add_using): No longer static.
 	* buildsym.h: Created global using_direct variable.
 	Created using_direct variable in context_stack.
 	* buildsym.c (finish_block): Set using directives for the block	under
 	construction.
 	(start_symtab): Removed call to cp_initialize_namespace().
 	(end_symtab): Removed call to cp_finalize_namespace().
 	(push_context): Save and reset using_directives.
 	* block.c (block_using): Return using directives for given
 	block instead of static block.


diff --git a/gdb/block.c b/gdb/block.c
index 8f0140c..9ebe975 100644
--- a/gdb/block.c
+++ b/gdb/block.c
@@ -206,25 +206,16 @@ block_set_scope (struct block *block, const char *scope,
   BLOCK_NAMESPACE (block)->scope = scope;
 }
 
-/* This returns the first using directives associated to BLOCK, if
+/* This returns the using directives list associated with BLOCK, if
    any.  */
 
-/* FIXME: carlton/2003-04-23: This uses the fact that we currently
-   only have using directives in static blocks, because we only
-   generate using directives from anonymous namespaces.  Eventually,
-   when we support using directives everywhere, we'll want to replace
-   this by some iterator functions.  */
-
 struct using_direct *
 block_using (const struct block *block)
 {
-  const struct block *static_block = block_static_block (block);
-
-  if (static_block == NULL
-      || BLOCK_NAMESPACE (static_block) == NULL)
+  if (block == NULL || BLOCK_NAMESPACE (block) == NULL)
     return NULL;
   else
-    return BLOCK_NAMESPACE (static_block)->using;
+    return BLOCK_NAMESPACE (block)->using;
 }
 
 /* Set BLOCK's using member to USING; if needed, allocate memory via
diff --git a/gdb/buildsym.c b/gdb/buildsym.c
index e7c48fe..e6ef9c6 100644
--- a/gdb/buildsym.c
+++ b/gdb/buildsym.c
@@ -384,6 +384,8 @@ finish_block (struct symbol *symbol, struct pending **listhead,
       opblock = pblock;
     }
 
+  block_set_using (block, using_directives, &objfile->objfile_obstack);
+
   record_pending_block (objfile, block, opblock);
 
   return block;
@@ -812,10 +814,6 @@ start_symtab (char *name, char *dirname, CORE_ADDR start_addr)
   /* We shouldn't have any address map at this point.  */
   gdb_assert (! pending_addrmap);
 
-  /* Set up support for C++ namespace support, in case we need it.  */
-
-  cp_initialize_namespace ();
-
   /* Initialize the list of sub source files with one entry for this
      file (the top-level source file).  */
 
@@ -1012,8 +1010,6 @@ end_symtab (CORE_ADDR end_addr, struct objfile *objfile, int section)
       finish_block (0, &global_symbols, 0, last_source_start_addr, end_addr,
 		    objfile);
       blockvector = make_blockvector (objfile);
-      cp_finalize_namespace (BLOCKVECTOR_BLOCK (blockvector, STATIC_BLOCK),
-			     &objfile->objfile_obstack);
     }
 
   /* Read the line table if it has to be read separately.  */
@@ -1225,10 +1221,12 @@ push_context (int desc, CORE_ADDR valu)
   new->params = param_symbols;
   new->old_blocks = pending_blocks;
   new->start_addr = valu;
+  new->using_directives = using_directives;
   new->name = NULL;
 
   local_symbols = NULL;
   param_symbols = NULL;
+  using_directives = NULL;
 
   return new;
 }
diff --git a/gdb/buildsym.h b/gdb/buildsym.h
index bf23ecc..6f8b09f 100644
--- a/gdb/buildsym.h
+++ b/gdb/buildsym.h
@@ -125,6 +125,10 @@ EXTERN struct pending *local_symbols;
 
 EXTERN struct pending *param_symbols;
 
+/* "using" directives local to lexical context.  */
+
+EXTERN struct using_direct *using_directives;
+
 /* Stack representing unclosed lexical contexts (that will become
    blocks, eventually).  */
 
@@ -138,6 +142,10 @@ struct context_stack
 
     struct pending *params;
 
+    /* Pending using directives at the time we entered.  */
+
+    struct using_direct *using_directives;
+
     /* Pointer into blocklist as of entry */
 
     struct pending_block *old_blocks;
diff --git a/gdb/cp-namespace.c b/gdb/cp-namespace.c
index c6c5617..f3b2194 100644
--- a/gdb/cp-namespace.c
+++ b/gdb/cp-namespace.c
@@ -30,15 +30,7 @@
 #include "dictionary.h"
 #include "command.h"
 #include "frame.h"
-
-/* List of using directives that are active in the current file.  */
-
-static struct using_direct *using_list;
-
-static struct using_direct *cp_add_using (const char *name,
-					  unsigned int inner_len,
-					  unsigned int outer_len,
-					  struct using_direct *next);
+#include "buildsym.h"
 
 static struct using_direct *cp_copy_usings (struct using_direct *using,
 					    struct obstack *obstack);
@@ -78,31 +70,6 @@ static struct symbol *lookup_possible_namespace_symbol (const char *name);
 
 static void maintenance_cplus_namespace (char *args, int from_tty);
 
-/* Set up support for dealing with C++ namespace info in the current
-   symtab.  */
-
-void cp_initialize_namespace ()
-{
-  using_list = NULL;
-}
-
-/* Add all the using directives we've gathered to the current symtab.
-   STATIC_BLOCK should be the symtab's static block; OBSTACK is used
-   for allocation.  */
-
-void
-cp_finalize_namespace (struct block *static_block,
-		       struct obstack *obstack)
-{
-  if (using_list != NULL)
-    {
-      block_set_using (static_block,
-		       cp_copy_usings (using_list, obstack),
-		       obstack);
-      using_list = NULL;
-    }
-}
-
 /* Check to see if SYMBOL refers to an object contained within an
    anonymous namespace; if so, add an appropriate using directive.  */
 
@@ -170,7 +137,7 @@ cp_add_using_directive (const char *name, unsigned int outer_length,
 
   /* Has it already been added?  */
 
-  for (current = using_list; current != NULL; current = current->next)
+  for (current = using_directives; current != NULL; current = current->next)
     {
       if ((strncmp (current->inner, name, inner_length) == 0)
 	  && (strlen (current->inner) == inner_length)
@@ -178,8 +145,8 @@ cp_add_using_directive (const char *name, unsigned int outer_length,
 	return;
     }
 
-  using_list = cp_add_using (name, inner_length, outer_length,
-			     using_list);
+  using_directives = cp_add_using (name, inner_length, outer_length,
+                                   using_directives);
 }
 
 /* Record the namespace that the function defined by SYMBOL was
@@ -237,7 +204,7 @@ cp_is_anonymous (const char *namespace)
    using xmalloc.  It copies the strings, so NAME can be a temporary
    string.  */
 
-static struct using_direct *
+struct using_direct *
 cp_add_using (const char *name,
 	      unsigned int inner_len,
 	      unsigned int outer_len,
diff --git a/gdb/cp-support.h b/gdb/cp-support.h
index 837ca6c..e577f7d 100644
--- a/gdb/cp-support.h
+++ b/gdb/cp-support.h
@@ -80,6 +80,11 @@ extern void cp_add_using_directive (const char *name,
 				    unsigned int outer_length,
 				    unsigned int inner_length);
 
+extern struct using_direct *cp_add_using (const char *name,
+					  unsigned int inner_len,
+					  unsigned int outer_len,
+					  struct using_direct *next);
+
 extern void cp_initialize_namespace (void);
 
 extern void cp_finalize_namespace (struct block *static_block,
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index ae8870c..6569798 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -946,6 +946,8 @@ static void read_namespace (struct die_info *die, struct dwarf2_cu *);
 
 static void read_module (struct die_info *die, struct dwarf2_cu *cu);
 
+static void read_import_statement (struct die_info *die, struct dwarf2_cu *);
+
 static const char *namespace_name (struct die_info *die,
 				   int *is_anonymous, struct dwarf2_cu *);
 
@@ -2984,14 +2986,12 @@ process_die (struct die_info *die, struct dwarf2_cu *cu)
       break;
     case DW_TAG_imported_declaration:
     case DW_TAG_imported_module:
-      /* FIXME: carlton/2002-10-16: Eventually, we should use the
-	 information contained in these.  DW_TAG_imported_declaration
-	 dies shouldn't have children; DW_TAG_imported_module dies
-	 shouldn't in the C++ case, but conceivably could in the
-	 Fortran case.  */
       processing_has_namespace_info = 1;
-      complaint (&symfile_complaints, _("unsupported tag: '%s'"),
-		 dwarf_tag_name (die->tag));
+      if (die->child != NULL && (die->tag == DW_TAG_imported_declaration
+				 || cu->language != language_fortran))
+	complaint (&symfile_complaints, _("Tag '%s' has unexpected children"),
+		   dwarf_tag_name (die->tag));
+      read_import_statement (die, cu);
       break;
     default:
       new_symbol (die, NULL, cu);
@@ -3037,6 +3037,69 @@ dwarf2_full_name (struct die_info *die, struct dwarf2_cu *cu)
   return name;
 }
 
+/* Read the import statement specified by the given die and record it.  */
+
+static void
+read_import_statement (struct die_info *die, struct dwarf2_cu *cu)
+{
+  struct attribute *import_attr;
+  struct die_info *imported_die;
+  const char *imported_name;
+  int is_anonymous = 0;
+
+  import_attr = dwarf2_attr (die, DW_AT_import, cu);
+  if (import_attr == NULL)
+    {
+      complaint (&symfile_complaints, _("Tag '%s' has no DW_AT_import"),
+		 dwarf_tag_name (die->tag));
+      return;
+    }
+
+  imported_die = follow_die_ref (die, import_attr, &cu);
+  imported_name = dwarf2_name (imported_die, cu);
+  if (imported_name == NULL)
+    {
+      /* GCC bug: https://bugzilla.redhat.com/show_bug.cgi?id=506524
+
+        The import in the following code:
+        namespace A
+          {
+            typedef int B;
+          }
+
+        int main ()
+          {
+            using A::B;
+            B b;
+            return b;
+          }
+
+        ...
+         <2><51>: Abbrev Number: 3 (DW_TAG_imported_declaration)
+            <52>   DW_AT_decl_file   : 1
+            <53>   DW_AT_decl_line   : 6
+            <54>   DW_AT_import      : <0x75>
+         <2><58>: Abbrev Number: 4 (DW_TAG_typedef)
+            <59>   DW_AT_name        : B
+            <5b>   DW_AT_decl_file   : 1
+            <5c>   DW_AT_decl_line   : 2
+            <5d>   DW_AT_type        : <0x6e>
+        ...
+         <1><75>: Abbrev Number: 7 (DW_TAG_base_type)
+            <76>   DW_AT_byte_size   : 4
+            <77>   DW_AT_encoding    : 5        (signed)
+
+        imports the wrong die ( 0x75 instead of 0x58 ).
+        This case will be ignored until the gcc bug is fixed.  */
+      return;
+    }
+
+  /* FIXME: dwarf2_name (die); for the local name after import.  */
+
+  using_directives = cp_add_using (imported_name, strlen (imported_name), 0,
+                                   using_directives);
+}
+
 static void
 initialize_cu_func_list (struct dwarf2_cu *cu)
 {
@@ -3370,6 +3433,7 @@ read_func_scope (struct die_info *die, struct dwarf2_cu *cu)
      back to building a containing block's symbol lists.  */
   local_symbols = new->locals;
   param_symbols = new->params;
+  using_directives = new->using_directives;
 
   /* If we've finished processing a top-level function, subsequent
      symbols go in the file symbol list.  */
@@ -3432,6 +3496,7 @@ read_lexical_block_scope (struct die_info *die, struct dwarf2_cu *cu)
       dwarf2_record_block_ranges (die, block, baseaddr, cu);
     }
   local_symbols = new->locals;
+  using_directives = new->using_directives;
 }
 
 /* Get low and high pc attributes from DW_AT_ranges attribute value OFFSET.