invoke.texi: Document -Wcast-function-type.

gcc:
2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * doc/invoke.texi: Document -Wcast-function-type.
        * recog.h (stored_funcptr): Change signature.
        * tree-dump.c (dump_node): Avoid warning.
        * typed-splay-tree.h (typed_splay_tree): Avoid warning.

libcpp:
2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * internal.h (maybe_print_line): Change signature.

c-family:
2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c.opt (Wcast-function-type): New warning option.
        * c-lex.c (get_fileinfo): Avoid warning.
        * c-ppoutput.c (scan_translation_unit_directives_only): Remove cast.

c:
2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-typeck.c (c_safe_arg_type_equiv_p,
        c_safe_function_type_cast_p): New function.
        (build_c_cast): Implement -Wcast-function-type.

cp:
2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * decl2.c (start_static_storage_duration_function): Avoid warning.
        * typeck.c (cxx_safe_arg_type_equiv_p,
        cxx_safe_function_type_cast_p): New function.
        (build_reinterpret_cast_1): Implement -Wcast-function-type.

testsuite:
2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-c++-common/Wcast-function-type.c: New test.
        * g++.dg/Wcast-function-type.C: New test.

From-SVN: r255661

3 files changed, 83 insertions, 4 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index ac6a8e1..d7a1dde 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2017-12-14  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	* decl2.c (start_static_storage_duration_function): Avoid warning.
+	* typeck.c (cxx_safe_arg_type_equiv_p,
+	cxx_safe_function_type_cast_p): New function.
+	(build_reinterpret_cast_1): Implement -Wcast-function-type.
+
 2017-12-14  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/79650
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 5d30369..89a940a 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -3558,7 +3558,8 @@ start_static_storage_duration_function (unsigned count)
       priority_info_map = splay_tree_new (splay_tree_compare_ints,
 					  /*delete_key_fn=*/0,
 					  /*delete_value_fn=*/
-					  (splay_tree_delete_value_fn) &free);
+					  (splay_tree_delete_value_fn)
+					  (void (*) (void)) free);
 
       /* We always need to generate functions for the
 	 DEFAULT_INIT_PRIORITY so enter it now.  That way when we walk
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 8f3302f..390aa15 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -1173,6 +1173,59 @@ comp_template_parms_position (tree t1, tree t2)
   return true;
 }
 
+/* Heuristic check if two parameter types can be considered ABI-equivalent.  */
+
+static bool
+cxx_safe_arg_type_equiv_p (tree t1, tree t2)
+{
+  t1 = TYPE_MAIN_VARIANT (t1);
+  t2 = TYPE_MAIN_VARIANT (t2);
+
+  if (TREE_CODE (t1) == POINTER_TYPE
+      && TREE_CODE (t2) == POINTER_TYPE)
+    return true;
+
+  /* The signedness of the parameter matters only when an integral
+     type smaller than int is promoted to int, otherwise only the
+     precision of the parameter matters.
+     This check should make sure that the callee does not see
+     undefined values in argument registers.  */
+  if (INTEGRAL_TYPE_P (t1)
+      && INTEGRAL_TYPE_P (t2)
+      && TYPE_PRECISION (t1) == TYPE_PRECISION (t2)
+      && (TYPE_UNSIGNED (t1) == TYPE_UNSIGNED (t2)
+	  || !targetm.calls.promote_prototypes (NULL_TREE)
+	  || TYPE_PRECISION (t1) >= TYPE_PRECISION (integer_type_node)))
+    return true;
+
+  return same_type_p (t1, t2);
+}
+
+/* Check if a type cast between two function types can be considered safe.  */
+
+static bool
+cxx_safe_function_type_cast_p (tree t1, tree t2)
+{
+  if (TREE_TYPE (t1) == void_type_node &&
+      TYPE_ARG_TYPES (t1) == void_list_node)
+    return true;
+
+  if (TREE_TYPE (t2) == void_type_node &&
+      TYPE_ARG_TYPES (t2) == void_list_node)
+    return true;
+
+  if (!cxx_safe_arg_type_equiv_p (TREE_TYPE (t1), TREE_TYPE (t2)))
+    return false;
+
+  for (t1 = TYPE_ARG_TYPES (t1), t2 = TYPE_ARG_TYPES (t2);
+       t1 && t2;
+       t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
+    if (!cxx_safe_arg_type_equiv_p (TREE_VALUE (t1), TREE_VALUE (t2)))
+      return false;
+
+  return true;
+}
+
 /* Subroutine in comptypes.  */
 
 static bool
@@ -7326,9 +7379,27 @@ build_reinterpret_cast_1 (tree type, tree expr, bool c_cast_p,
 	   && same_type_p (type, intype))
     /* DR 799 */
     return rvalue (expr);
-  else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
-	   || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
-    return build_nop (type, expr);
+  else if (TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
+    {
+      if ((complain & tf_warning)
+	  && !cxx_safe_function_type_cast_p (TREE_TYPE (type),
+					     TREE_TYPE (intype)))
+	warning (OPT_Wcast_function_type,
+		 "cast between incompatible function types"
+		 " from %qH to %qI", intype, type);
+      return build_nop (type, expr);
+    }
+  else if (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype))
+    {
+      if ((complain & tf_warning)
+	  && !cxx_safe_function_type_cast_p
+		(TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE_RAW (type)),
+		 TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE_RAW (intype))))
+	warning (OPT_Wcast_function_type,
+		 "cast between incompatible pointer to member types"
+		 " from %qH to %qI", intype, type);
+      return build_nop (type, expr);
+    }
   else if ((TYPE_PTRDATAMEM_P (type) && TYPE_PTRDATAMEM_P (intype))
 	   || (TYPE_PTROBV_P (type) && TYPE_PTROBV_P (intype)))
     {