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.

From-SVN: r178692

15 files changed, 378 insertions, 9 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a0a89bb..9c6b1ee 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,23 @@
+2011-09-08  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/33255 - Support -Wunused-local-typedefs warning
+	* 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.
+	* doc/invoke.texi: Update documentation for
+	-Wunused-local-typedefs.
+
 2011-09-08  Enkovich Ilya  <ilya.enkovich@intel.com>
 
 	* config/i386/i386-protos.h (ix86_lea_outperforms): New.
diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index d683d4e..5d4564a 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)
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 347d904..080d42a 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,15 @@
+2011-09-08  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/33255 - Support -Wunused-local-typedefs warning
+	* 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.
+
 2011-09-06  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR middle-end/50266
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index d8028d3..e2852b6 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -6133,7 +6133,8 @@ handle_used_attribute (tree *pnode, tree name, tree ARG_UNUSED (args),
   tree node = *pnode;
 
   if (TREE_CODE (node) == FUNCTION_DECL
-      || (TREE_CODE (node) == VAR_DECL && TREE_STATIC (node)))
+      || (TREE_CODE (node) == VAR_DECL && TREE_STATIC (node))
+      || (TREE_CODE (node) == TYPE_DECL))
     {
       TREE_USED (node) = 1;
       DECL_PRESERVE_P (node) = 1;
@@ -9646,6 +9647,76 @@ record_types_used_by_current_var_decl (tree decl)
     }
 }
 
+/* If DECL is a typedef that is declared in the current function,
+   record it for the purpose of -Wunused-local-typedefs.  */
+
+void
+record_locally_defined_typedef (tree decl)
+{
+  struct c_language_function *l;
+
+  if (!warn_unused_local_typedefs
+      || cfun == NULL
+      /* if this is not a locally defined typedef then we are not
+	 interested.  */
+      || !is_typedef_decl (decl)
+      || !decl_function_context (decl))
+    return;
+
+  l = (struct c_language_function *) cfun->language;
+  VEC_safe_push (tree, gc, l->local_typedefs, decl);
+}
+
+/* If T is a TYPE_DECL declared locally, mark it as used.  */
+
+void
+maybe_record_typedef_use (tree t)
+{
+  if (!is_typedef_decl (t))
+    return;
+
+  TREE_USED (t) = true;
+}
+
+/* Warn if there are some unused locally defined typedefs in the
+   current function. */
+
+void
+maybe_warn_unused_local_typedefs (void)
+{
+  int i;
+  tree decl;
+  /* The number of times we have emitted -Wunused-local-typedefs
+     warnings.  If this is different from errorcount, that means some
+     unrelated errors have been issued.  In which case, we'll avoid
+     emitting "unused-local-typedefs" warnings.  */
+  static int unused_local_typedefs_warn_count;
+  struct c_language_function *l;
+
+  if (cfun == NULL)
+    return;
+
+  if ((l = (struct c_language_function *) cfun->language) == NULL)
+    return;
+
+  if (warn_unused_local_typedefs
+      && errorcount == unused_local_typedefs_warn_count)
+    {
+      FOR_EACH_VEC_ELT (tree, l->local_typedefs, i, decl)
+	if (!TREE_USED (decl))
+	  warning_at (DECL_SOURCE_LOCATION (decl),
+		      OPT_Wunused_local_typedefs,
+		      "typedef %qD locally defined but not used", decl);
+      unused_local_typedefs_warn_count = errorcount;
+    }
+
+  if (l->local_typedefs)
+    {
+      VEC_free (tree, gc, l->local_typedefs);
+      l->local_typedefs = NULL;
+    }
+}
+
 /* The C and C++ parsers both use vectors to hold function arguments.
    For efficiency, we keep a cache of unused vectors.  This is the
    cache.  */
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 7ad82c0..7241d66 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -506,6 +506,10 @@ struct GTY(()) c_language_function {
   /* While we are parsing the function, this contains information
      about the statement-tree that we are building.  */
   struct stmt_tree_s x_stmt_tree;
+
+  /* Vector of locally defined typedefs, for
+     -Wunused-local-typedefs.  */
+  VEC(tree,gc) *local_typedefs;
 };
 
 #define stmt_list_stack (current_stmt_tree ()->x_cur_stmt_list)
@@ -988,6 +992,9 @@ extern void warn_for_sign_compare (location_t,
 extern void do_warn_double_promotion (tree, tree, tree, const char *, 
 				      location_t);
 extern void set_underlying_type (tree);
+extern void record_locally_defined_typedef (tree);
+extern void maybe_record_typedef_use (tree);
+extern void maybe_warn_unused_local_typedefs (void);
 extern VEC(tree,gc) *make_tree_vector (void);
 extern void release_tree_vector (VEC(tree,gc) *);
 extern VEC(tree,gc) *make_tree_vector_single (tree);
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 617ea2d..e6ac5dc 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -653,6 +653,10 @@ Wunsuffixed-float-constants
 C ObjC Var(warn_unsuffixed_float_constants) Warning
 Warn about unsuffixed float constants
 
+Wunused-local-typedefs
+C ObjC C++ ObjC++ Var(warn_unused_local_typedefs) Warning
+Warn about
+
 Wunused-macros
 C ObjC C++ ObjC++ Warning
 Warn about macros defined in the main file that are not used
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 9810d7d..8ee3087 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,13 @@
+2011-09-08  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/33255 - Support -Wunused-local-typedefs warning
+	* 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.
+
 2011-09-07  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/50309
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index e30fe18..a68bcb1240 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -13392,6 +13392,10 @@ finish_function (int flags)
       unused_but_set_errorcount = errorcount;
     }
 
+  /* Complain about locally defined typedefs that are not used in this
+     function.  */
+  maybe_warn_unused_local_typedefs ();
+
   /* Genericize before inlining.  */
   if (!processing_template_decl)
     {
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index f05b0f8..68e9b9b 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -868,6 +868,7 @@ grokfield (const cp_declarator *declarator,
           && TYPE_NAME (TYPE_MAIN_VARIANT (TREE_TYPE (value))) != value)
 	set_underlying_type (value);
 
+      record_locally_defined_typedef (value);
       return value;
     }
 
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 64456b4..4219548 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -868,6 +868,13 @@ pushdecl_maybe_friend_1 (tree x, bool is_friend)
 	      && TYPE_NAME (type)
 	      && TYPE_IDENTIFIER (type))
 	    set_identifier_type_value (DECL_NAME (x), x);
+
+	  /* If this is a locally defined typedef in a function that
+	     is not a template instantation, record it to implement
+	     -Wunused-local-typedefs.  */
+	  if (current_instantiation () == NULL
+	      || (current_instantiation ()->decl != current_function_decl))
+	  record_locally_defined_typedef (x);
 	}
 
       /* Multiple external decls of the same identifier ought to match.
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 6346aa0..03f75fc 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -19587,6 +19587,8 @@ cp_parser_lookup_name (cp_parser *parser, tree name,
   if (DECL_P (decl))
     check_accessibility_of_qualified_id (decl, object_type, parser->scope);
 
+  maybe_record_typedef_use (decl);
+
   return decl;
 }
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index b1ff187..3aa9611 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -268,8 +268,9 @@ Objective-C and Objective-C++ Dialects}.
 -Wsystem-headers  -Wtrampolines  -Wtrigraphs  -Wtype-limits  -Wundef @gol
 -Wuninitialized  -Wunknown-pragmas  -Wno-pragmas @gol
 -Wunsuffixed-float-constants  -Wunused  -Wunused-function @gol
--Wunused-label  -Wunused-parameter -Wno-unused-result -Wunused-value @gol
--Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable @gol
+-Wunused-label  -Wunused-local-typedefs -Wunused-parameter @gol
+-Wno-unused-result -Wunused-value @gol -Wunused-variable @gol
+-Wunused-but-set-parameter -Wunused-but-set-variable @gol
 -Wvariadic-macros -Wvla -Wvolatile-register-var  -Wwrite-strings}
 
 @item C and Objective-C-only Warning Options
@@ -3501,6 +3502,10 @@ This warning is enabled by @option{-Wall}.
 To suppress this warning use the @samp{unused} attribute
 (@pxref{Variable Attributes}).
 
+@item -Wunused-local-typedefs @r{(C, Objective-C, C++ and Objective-C++ only)}
+@opindex Wunused-local-typedefs
+Warn when a typedef locally defined in a function is not used.
+
 @item -Wunused-parameter
 @opindex Wunused-parameter
 @opindex Wno-unused-parameter
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fecb2f4..e6c4db0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2011-09-08  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/33255 - Support -Wunused-local-typedefs warning
+	* g++.dg/warn/Wunused-local-typedefs.C: New test file.
+	* c-c++-common/Wunused-local-typedefs.c: Likewise.
+
 2011-09-08  Martin Jambor  <mjambor@suse.cz>
 
 	PR tree-optimization/50287
diff --git a/gcc/testsuite/c-c++-common/Wunused-local-typedefs.c b/gcc/testsuite/c-c++-common/Wunused-local-typedefs.c
new file mode 100644
index 0000000..683019d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wunused-local-typedefs.c
@@ -0,0 +1,44 @@
+/*  Origin PR c++/33255
+    { dg-options "-Wunused-local-typedefs" }
+    { dg-do compile }
+*/
+
+void
+test_warn ()
+{
+  typedef int foo; // { dg-warning "locally defined but not used" }
+}
+
+void
+test0 ()
+{
+    typedef int foo;
+    foo var __attribute__((unused));
+}
+
+void
+test1 ()
+{
+    typedef int foo;
+    const foo *var = 0;
+}
+
+void
+test2 ()
+{
+  typedef int foo;
+  void func(foo);  
+}
+
+void
+test7 (void)
+{
+  typedef int foo;
+  int vec[1] = {sizeof (foo)};
+}
+
+void
+test8 (void)
+{
+  typedef int foo __attribute__((used));
+}
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-local-typedefs.C b/gcc/testsuite/g++.dg/warn/Wunused-local-typedefs.C
new file mode 100644
index 0000000..87feb52
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-local-typedefs.C
@@ -0,0 +1,146 @@
+// Origin PR c++/33255
+// { dg-options "-Wunused-local-typedefs" }
+// { dg-do compile }
+
+void
+test_warn()
+{
+  typedef int foo; // { dg-warning "locally defined but not used" }
+}
+
+struct S
+{
+    typedef int T;
+    S() {}
+    S(int) {}
+};
+
+template<class T>
+struct ST
+{
+    typedef T type;
+    ST (int) {}
+    ST () {}
+};
+
+template<class T>
+void
+test0_tmpl(void)
+{
+    typedef struct ST<T> foo;
+    foo(2);
+}
+
+int
+test0(void)
+{
+    test0_tmpl<int>();
+}
+
+void
+test1(void)
+{
+    typedef int foo;
+    ST<foo> a;
+}
+
+
+int
+test2(void)
+{
+    typedef S foo;
+    foo::T i = 0;
+    return i;
+}
+
+template<class T>
+void
+test3_tmpl(void)
+{
+    typedef struct ST<int> foo;
+    ST<int> v;
+    const foo &var = v;
+}
+
+void
+test3(void)
+{
+    test3_tmpl<int>();
+}
+
+void
+test4(void)
+{
+  typedef int foo;
+  int vec[1] = {sizeof (foo)};
+}
+
+void
+test5(void)
+{
+  typedef int T0;
+  typedef char T1;
+  typedef int* T2;
+  typedef unsigned T3;
+  struct C0 { virtual void f(void) {}};
+  struct C1 : C0 {};
+  typedef C0 T4;
+
+  int v0 = (T0) 2;
+  char v1 = static_cast<T1> (0);
+  reinterpret_cast<T2> (&v0);
+  unsigned* const c = 0;
+  unsigned* v2 = const_cast<T3* const> (c);
+  C0 *p0 = 0;
+  C1 *p1 = 0;
+  p0 = dynamic_cast<T4*> (p1);  
+}
+
+void
+test6(void)
+{
+  struct C0 {};
+  typedef C0 foo;
+  C0 *v = new foo;
+}
+
+template<class T, class U>
+struct S7
+{
+  void
+  f()
+  {
+    typedef int foo;
+    sizeof(foo);
+  }
+};
+
+template<class T>
+void
+test7(void)
+{
+  typedef typename ST<T>::T bar; // { dg-warning "locally defined but not used" }
+  typedef typename ST<T>::T foo; // We shouldn't warn for this one, as
+				 // it's used below.
+  S7<int, foo> v;
+}
+
+
+template<class T, class U>
+void
+test8(void)
+{
+  int f(S7<T, U>);
+  void g(int);
+  typedef T foo;
+  g(f(S7<foo, U>()));
+}
+
+int
+test9(void)
+{
+  struct s { typedef int foo;}; // { dg-warning "locally defined but not used" }
+  struct t { typedef int bar;};
+  t::bar b = 0;
+  return b;
+}