Implement DR 757: It's OK for a decl to use a type without linkage

	so long as the decl is defined in the current translation unit.
	* decl2.c (no_linkage_decls): New vector.
	(mark_used): Add decls that use types with no linkage.
	(cp_write_global_declarations): Check that they are defined.
	(decl_defined_p, no_linkage_error): New fns.
	* cp-tree.h (DECL_NO_LINKAGE_CHECKED): New macro.
	(struct lang_decl_base): Add flag.
	* decl.c (grokfndecl): Don't check type linkage.
	(grokvardecl): If the type has no linkage, just make sure
	DECL_LANG_SPECIFIC is set.
	* pt.c (check_instantiated_arg): Don't check type linkage.
	* name-lookup.c (is_local_extern): New fn.
	* name-lookup.h: Declare it.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@150634 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 28 insertions, 0 deletions

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index c2d877907bc..feb2cf280d1 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -4392,6 +4392,34 @@ lookup_name_innermost_nonclass_level (tree name)
   POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, t);
 }
 
+/* Returns true iff DECL is a block-scope extern declaration of a function
+   or variable.  */
+
+bool
+is_local_extern (tree decl)
+{
+  cxx_binding *binding;
+
+  /* For functions, this is easy.  */
+  if (TREE_CODE (decl) == FUNCTION_DECL)
+    return DECL_LOCAL_FUNCTION_P (decl);
+
+  if (TREE_CODE (decl) != VAR_DECL)
+    return false;
+  if (!current_function_decl)
+    return false;
+
+  /* For variables, this is not easy.  We need to look at the binding stack
+     for the identifier to see whether the decl we have is a local.  */
+  for (binding = IDENTIFIER_BINDING (DECL_NAME (decl));
+       binding && binding->scope->kind != sk_namespace;
+       binding = binding->previous)
+    if (binding->value == decl)
+      return LOCAL_BINDING_P (binding);
+
+  return false;
+}
+
 /* Like lookup_name_innermost_nonclass_level, but for types.  */
 
 static tree