PR c++/33255 - Support -Wunused-local-typedefs warning

gcc/

	* c-decl.c (lookup_name): Use the new
	maybe_record_typedef_use.
	(pushdecl): Use the new
	record_locally_defined_typedef.
	(store_parm_decls): Allocate cfun->language.
	(finish_function): Use the new maybe_warn_unused_local_typedefs,
	and free cfun->language.
	(c_push_function_context): Allocate cfun->language here only if
	needed.
	(c_pop_function_context): Likewise, mark cfun->language
	for collection only when it should be done.
	* c-common.c (handle_used_attribute): Don't ignore TYPE_DECL
	nodes.
	* c-typeck.c (c_expr_sizeof_type, c_cast_expr): Use the new
	maybe_record_local_typedef_use.

gcc/c-family

	* c-common.h (struct c_language_function::local_typedefs): New
	field.
	(record_locally_defined_typedef, maybe_record_typedef_use)
	(maybe_warn_unused_local_typedefs): Declare new functions.
	* c-common.c (record_locally_defined_typedef)
	(maybe_record_typedef_use)
	(maybe_warn_unused_local_typedefs): Define new functions.
	* c.opt: Declare new -Wunused-local-typedefs flag.

gcc/cp

	* name-lookup.c (pushdecl_maybe_friend_1): Use the new
	record_locally_defined_typedef.
	* decl.c (finish_function): Use the new
	maybe_warn_unused_local_typedefs.
	(grokfield): Use the new record_locally_defined_typedef.
	* parser.c (lookup_name): Use the new maybe_record_typedef_use.

gcc/doc/

	* invoke.texi: Update documentation for -Wunused-local-typedefs.

gcc/testsuite/

	* g++.dg/warn/Wunused-local-typedefs.C: New test file.
	* c-c++-common/Wunused-local-typedefs.c: Likewise.

libstdc++-v3/

	* include/ext/bitmap_allocator.h
	(__detail::__mini_vector::__lower_bound): Remove unused typedef.
	* src/istream.cc (std::operator>>(basic_istream<char>& __in,
	basic_string<char>& __str)): Likewise.
	(std::getline): Likewise.
	* src/valarray.cc (__valarray_product): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@178692 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 36 insertions, 6 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index d683d4e3655..5d4564abc87 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -2769,7 +2769,15 @@ pushdecl (tree x)
 
  skip_external_and_shadow_checks:
   if (TREE_CODE (x) == TYPE_DECL)
-    set_underlying_type (x);
+    {
+      /* So this is a typedef, set its underlying type.  */
+      set_underlying_type (x);
+
+      /* If X is a typedef defined in the current function, record it
+	 for the purpose of implementing the -Wunused-local-typedefs
+	 warning.  */
+      record_locally_defined_typedef (x);
+    }
 
   bind (name, x, scope, /*invisible=*/false, nested, locus);
 
@@ -3435,7 +3443,10 @@ lookup_name (tree name)
 {
   struct c_binding *b = I_SYMBOL_BINDING (name);
   if (b && !b->invisible)
-    return b->decl;
+    {
+      maybe_record_typedef_use (b->decl);
+      return b->decl;
+    }
   return 0;
 }
 
@@ -8192,6 +8203,9 @@ store_parm_decls (void)
   /* Initialize the RTL code for the function.  */
   allocate_struct_function (fndecl, false);
 
+  if (warn_unused_local_typedefs)
+    cfun->language = ggc_alloc_cleared_language_function ();
+
   /* Begin the statement tree for this function.  */
   DECL_SAVED_TREE (fndecl) = push_stmt_list ();
 
@@ -8299,6 +8313,10 @@ finish_function (void)
 		      "parameter %qD set but not used", decl);
     }
 
+  /* Complain about locally defined typedefs that are not used in this
+     function.  */
+  maybe_warn_unused_local_typedefs ();
+
   /* Store the end of the function, so that we get good line number
      info for the epilogue.  */
   cfun->function_end_locus = input_location;
@@ -8344,6 +8362,12 @@ finish_function (void)
   if (!decl_function_context (fndecl))
     undef_nested_function = false;
 
+  if (cfun->language != NULL)
+    {
+      ggc_free (cfun->language);
+      cfun->language = NULL;
+    }
+
   /* We're leaving the context of this function, so zap cfun.
      It's still in DECL_STRUCT_FUNCTION, and we'll restore it in
      tree_rest_of_compilation.  */
@@ -8455,9 +8479,11 @@ check_for_loop_decls (location_t loc, bool turn_off_iso_c99_error)
 void
 c_push_function_context (void)
 {
-  struct language_function *p;
-  p = ggc_alloc_language_function ();
-  cfun->language = p;
+  struct language_function *p = cfun->language;
+  /* cfun->language might have been already allocated by the use of
+     -Wunused-local-typedefs.  In that case, just re-use it.  */
+  if (p == NULL)
+    cfun->language = p = ggc_alloc_cleared_language_function ();
 
   p->base.x_stmt_tree = c_stmt_tree;
   c_stmt_tree.x_cur_stmt_list
@@ -8483,7 +8509,11 @@ c_pop_function_context (void)
 
   pop_function_context ();
   p = cfun->language;
-  cfun->language = NULL;
+  /* When -Wunused-local-typedefs is in effect, cfun->languages is
+     used to store data throughout the life time of the current cfun,
+     So don't deallocate it.  */
+  if (!warn_unused_local_typedefs)
+    cfun->language = NULL;
 
   if (DECL_STRUCT_FUNCTION (current_function_decl) == 0
       && DECL_SAVED_TREE (current_function_decl) == NULL_TREE)