[patch 1/2] Perform a namespace lookup at every block level

[Sami Wagiaalla <swagiaal at redhat dot com>]

> cp_lookup_symbol_namespace did two things look in the current namespace
> as well as examine applicable imports. I realized that we didnt need to
> examine imports at each scope level. We can simply look at the import
> destination.
>
> This patch separates the two kinds of lookups (imports and scopes) and
> performs the import lookup at every block level.

Same as above, but I fixed a couple of issues with the previous patch.
The first issue is that even while we iterate over blocks the original
scope should be used. Secondly, the call to lookup_symbol_name space
in valops.c must also perform a per block search. The final issue is
recursive search which is discussed in part 2 of this patch.

----

2009-08-11  Sami Wagiaalla  <swagiaal@redhat.com>

	* dwarf2read.c (read_lexical_block_scope): Create blocks for scopes
      	which contain using directives even if they contain no declarations.
       	* symtab.c (lookup_symbol_aux): Pass lowest level
       	block to la_lookup_symbol_nonlocal.
       	* cp-namespace.c (cp_lookup_symbol_nonlocal): call
       	cp_lookup_symbol_namespace.
       	(cp_lookup_symbol_namespace): Perform an import lookup at every block
       	level.
       	(cp_lookup_symbol_imports): New function.
       	(cp_lookup_symbol_in_namespace): New function.

2009-08-11  Sami Wagiaalla  <swagiaal@redhat.com>

       	* gdb.cp/namespace-using.exp: Add test for printing of namespaces
       	imported into file scope.
       	Marked test as xfail.
       	* gdb.cp/namespace-using.cc (marker5): New function.

diff --git a/gdb/cp-namespace.c b/gdb/cp-namespace.c
index d2d8f2e..a0ccd7f 100644
--- a/gdb/cp-namespace.c
+++ b/gdb/cp-namespace.c
@@ -42,6 +42,18 @@ static struct symbol *lookup_namespace_scope (const char *name,
 					      const char *scope,
 					      int scope_len);

+static struct symbol *cp_lookup_symbol_imports (const char *scope,
+                                                const char *name,
+                                                const char *linkage_name,
+                                                const struct block *block,
+                                                const domain_enum domain);
+
+static struct symbol *cp_lookup_symbol_in_namespace (const char *namespace,
+                                                     const char *name,
+                                                     const char *linkage_name,
+                                                     const struct block *block,
+                                                     const domain_enum domain);
+
 static struct symbol *lookup_symbol_file (const char *name,
 					  const char *linkage_name,
 					  const struct block *block,
@@ -265,8 +277,41 @@ cp_lookup_symbol_nonlocal (const char *name,
 			   const struct block *block,
 			   const domain_enum domain)
 {
-  return lookup_namespace_scope (name, linkage_name, block, domain,
-				 block_scope (block), 0);
+  struct symbol *sym;
+  const char *scope = block_scope (block);
+
+  sym = lookup_namespace_scope (name, linkage_name, block, domain, scope, 0);
+  if ( sym != NULL)
+    return sym;
+
+  return cp_lookup_symbol_namespace(scope, name, linkage_name, block, domain);
+}
+
+/* Searches for NAME in the current namespace, and by applying relevant import
+   statements belonging to BLOCK and its parents. SCOPE is the namespace scope
+   of the context in which the search is being evaluated.  */
+
+struct symbol*
+cp_lookup_symbol_namespace (const char *scope,
+                            const char *name,
+                            const char *linkage_name,
+                            const struct block *block,
+                            const domain_enum domain)
+{
+  struct symbol *sym;
+
+  /* Search for name in namespaces imported to this and parent blocks.  */
+  while (block != NULL)
+    {
+      sym = cp_lookup_symbol_imports(scope,name, linkage_name, block, domain);
+
+      if (sym)
+        return sym;
+
+      block = BLOCK_SUPERBLOCK(block);
+    }
+
+  return NULL;
 }

 /* Lookup NAME at namespace scope (or, in C terms, in static and
@@ -320,25 +365,59 @@ lookup_namespace_scope (const char *name,
   namespace = alloca (scope_len + 1);
   strncpy (namespace, scope, scope_len);
   namespace[scope_len] = '\0';
-  return cp_lookup_symbol_namespace (namespace, name, linkage_name,
+  return cp_lookup_symbol_in_namespace (namespace, name, linkage_name,
 				     block, domain);
 }

-/* Look up NAME in the C++ namespace NAMESPACE, applying the using
-   directives that are active in BLOCK.  Other arguments are as in
+/* Look up NAME in the C++ namespace NAMESPACE. Other arguments are as in
    cp_lookup_symbol_nonlocal.  */

-struct symbol *
-cp_lookup_symbol_namespace (const char *namespace,
-			    const char *name,
-			    const char *linkage_name,
-			    const struct block *block,
-			    const domain_enum domain)
+static struct symbol *
+cp_lookup_symbol_in_namespace (const char *namespace,
+			       const char *name,
+			       const char *linkage_name,
+			       const struct block *block,
+			       const domain_enum domain)
+{
+
+  if (namespace[0] == '\0')
+    {
+      return lookup_symbol_file (name, linkage_name, block,
+				 domain, 0);
+    }
+  else
+    {
+      char *concatenated_name
+	= alloca (strlen (namespace) + 2 + strlen (name) + 1);
+      strcpy (concatenated_name, namespace);
+      strcat (concatenated_name, "::");
+      strcat (concatenated_name, name);
+      return lookup_symbol_file (concatenated_name, linkage_name,
+				block, domain,
+				cp_is_anonymous (namespace));
+    }
+}
+
+/* Search for NAME by applying all import statements belonging
+   to BLOCK which are applicable in SCOPE.  */
+
+static struct symbol *
+cp_lookup_symbol_imports (const char *scope,
+                            const char *name,
+                            const char *linkage_name,
+                            const struct block *block,
+                            const domain_enum domain)
 {
   const struct using_direct *current;
   struct symbol *sym;

-  /* First, go through the using directives.  If any of them add new
+  /* First, try to find the symbol in the given namespace.  */
+  sym = cp_lookup_symbol_in_namespace (scope, name, linkage_name, block,
+                                       domain);
+  if ( sym != NULL)
+    return sym;
+
+  /* Go through the using directives.  If any of them add new
      names to the namespace we're searching in, see if we can find a
      match by applying them.  */

@@ -346,9 +425,12 @@ cp_lookup_symbol_namespace (const char *namespace,
        current != NULL;
        current = current->next)
     {
-      if (strcmp (namespace, current->import_dest) == 0)
+
+      /* If the import destination is the current scope or one of its ancestors then
+         it is applicable.  */
+      if (strncmp (scope, current->import_dest, strlen(current->import_dest)) == 0)
 	{
-	  sym = cp_lookup_symbol_namespace (current->import_src,
+	  sym = cp_lookup_symbol_in_namespace (current->import_src,
 					    name,
 					    linkage_name,
 					    block,
@@ -358,27 +440,7 @@ cp_lookup_symbol_namespace (const char *namespace,
 	}
     }

-  /* We didn't find anything by applying any of the using directives
-     that are still applicable; so let's see if we've got a match
-     using the current namespace.  */
-
-  if (namespace[0] == '\0')
-    {
-      return lookup_symbol_file (name, linkage_name, block,
-				 domain, 0);
-    }
-  else
-    {
-      char *concatenated_name
-	= alloca (strlen (namespace) + 2 + strlen (name) + 1);
-      strcpy (concatenated_name, namespace);
-      strcat (concatenated_name, "::");
-      strcat (concatenated_name, name);
-      sym = lookup_symbol_file (concatenated_name, linkage_name,
-				block, domain,
-				cp_is_anonymous (namespace));
-      return sym;
-    }
+  return NULL;
 }

 /* Look up NAME in BLOCK's static block and in global blocks.  If
@@ -461,7 +523,7 @@ cp_lookup_nested_type (struct type *parent_type,
 	   lookup_symbol_namespace works when looking them up.  */

 	const char *parent_name = TYPE_TAG_NAME (parent_type);
-	struct symbol *sym = cp_lookup_symbol_namespace (parent_name,
+	struct symbol *sym = cp_lookup_symbol_in_namespace (parent_name,
 							 nested_name,
 							 NULL,
 							 block,
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 445bab8..f18d804 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -3922,7 +3922,7 @@ read_lexical_block_scope (struct die_info *die, struct dwarf2_cu *cu)
     }
   new = pop_context ();

-  if (local_symbols != NULL)
+  if (local_symbols != NULL || using_directives != NULL)
     {
       struct block *block
         = finish_block (0, &local_symbols, new->old_blocks, new->start_addr,
diff --git a/gdb/symtab.c b/gdb/symtab.c
index c88156a..cebbb4b 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1304,13 +1304,14 @@ lookup_symbol_aux (const char *name, const char *linkage_name,
       && block != NULL)
     {
       struct symbol *sym = NULL;
+      const struct block *function_block = block;
       /* 'this' is only defined in the function's block, so find the
 	 enclosing function block.  */
-      for (; block && !BLOCK_FUNCTION (block);
-	   block = BLOCK_SUPERBLOCK (block));
+      for (; function_block && !BLOCK_FUNCTION (function_block);
+      function_block = BLOCK_SUPERBLOCK (function_block));

-      if (block && !dict_empty (BLOCK_DICT (block)))
-	sym = lookup_block_symbol (block, langdef->la_name_of_this,
+      if (function_block && !dict_empty (BLOCK_DICT (function_block)))
+	sym = lookup_block_symbol (function_block, langdef->la_name_of_this,
 				   NULL, VAR_DOMAIN);
       if (sym)
 	{
@@ -1334,11 +1335,14 @@ lookup_symbol_aux (const char *name, const char *linkage_name,
 	      return NULL;
 	    }
 	}
-    }

-  /* Now do whatever is appropriate for LANGUAGE to look
-     up static and global variables.  */
+      /* C++ language specific lookup requires the lowest block level.  */
+      if (language != language_cplus)
+        block = function_block;
+
+    }

+  /* Now do whatever is appropriate for LANGUAGE specific lookup.  */
   sym = langdef->la_lookup_symbol_nonlocal (name, linkage_name, block, domain);
   if (sym != NULL)
     return sym;
diff --git a/gdb/testsuite/gdb.cp/namespace-using.cc b/gdb/testsuite/gdb.cp/namespace-using.cc
index 4786fd5..091b4cc 100644
--- a/gdb/testsuite/gdb.cp/namespace-using.cc
+++ b/gdb/testsuite/gdb.cp/namespace-using.cc
@@ -1,3 +1,16 @@
+namespace C
+{
+  int cc = 3;
+}
+
+using namespace C;
+int marker5()
+{
+  cc;
+  return 0;
+}
+
+
 namespace A
 {
   int _a = 1;
@@ -6,7 +19,7 @@ namespace A

 int marker4(){
 	using A::x;
-	return 0;
+  return marker5();
 }

 int marker3(){
diff --git a/gdb/testsuite/gdb.cp/namespace-using.exp b/gdb/testsuite/gdb.cp/namespace-using.exp
index f24973f..bd1016b 100644
--- a/gdb/testsuite/gdb.cp/namespace-using.exp
+++ b/gdb/testsuite/gdb.cp/namespace-using.exp
@@ -28,6 +28,11 @@ if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {deb
     return -1
 }

+if [get_compiler_info ${binfile}] {
+    return -1;
+}
+
+
 # Get things started.

 gdb_exit
@@ -73,7 +78,13 @@ gdb_test "print B::a" "= 1"
 gdb_breakpoint "marker3"
 gdb_continue_to_breakpoint "marker3"

-gdb_test "print _a" "No symbol \"_a\" in current context." "Print a without import"
+# gcc-4-3 puts import statements for aliases in
+# the global scope instead of the corresponding
+# function scope. These wrong import statements throw
+# this test off. This is fixed in gcc-4-4.
+if [test_compiler_info gcc-4-3-*] then { setup_xfail *-*-* }
+
+gdb_test "print _a" "No symbol \"_a\" in current context." "Print _a without import"

 ############################################
 # Test printing of individually imported elements
@@ -85,3 +96,14 @@ if ![runto marker4] then {
 }

 gdb_test "print x" "= 2"
+
+############################################
+# test printing of namespace imported into
+# file scope.
+
+if ![runto marker5] then {
+    perror "couldn't run to marker5"
+    continue
+}
+
+gdb_test "print cc" "= 3"