invoke.texi (-Wsizeof-pointer-memaccess): Document.

	* doc/invoke.texi (-Wsizeof-pointer-memaccess): Document.
c/
	* c-tree.h (c_last_sizeof_arg): Declare.
	* c-parser.c (struct c_tree_loc_pair): New type.
	(c_parser_expr_list): Add sizeof_arg argument.  Fill it in if
	non-NULL.
	(c_parser_attributes, c_parser_objc_keywordexpr): Adjust callers.
	(c_parser_postfix_expression_after_primary): Likewise.  Call
	sizeof_pointer_memaccess_warning if needed.
	(sizeof_ptr_memacc_comptypes): New function.
	* c-typeck.c (c_last_sizeof_arg): New global variable.
	(c_expr_sizeof_expr, c_expr_sizeof_type): Initialize it.
cp/
	* cp-tree.def (SIZEOF_EXPR): Move to c-common.def.
c-family/
	* c-common.c (sizeof_pointer_memaccess_warning): New function.
	* c.opt (-Wsizeof-pointer-memaccess): Add new option.
	* c-opts.c (c_common_handle_option): Enable it for -Wall.
	* c-common.h (sizeof_pointer_memaccess_warning): Add prototype.
	* c-common.def (SIZEOF_EXPR): Moved here from cp-tree.def.
fortran/
	* array.c (gfc_match_array_ref): Fix up memset arguments.
testsuite/
	* gcc.dg/torture/Wsizeof-pointer-memaccess1.c: New test.

From-SVN: r190467

6 files changed, 167 insertions, 5 deletions

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index c460b35..2ce3f59 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,11 @@
+2012-08-17  Jakub Jelinek  <jakub@redhat.com>
+
+	* c-common.c (sizeof_pointer_memaccess_warning): New function.
+	* c.opt (-Wsizeof-pointer-memaccess): Add new option.
+	* c-opts.c (c_common_handle_option): Enable it for -Wall.
+	* c-common.h (sizeof_pointer_memaccess_warning): Add prototype.
+	* c-common.def (SIZEOF_EXPR): Moved here from cp-tree.def.
+
 2012-08-10  Richard Guenther  <rguenther@suse.de>
 
 	* c-pretty-print.c (pp_c_expression): Handle anonymous SSA names.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index ab3eb0a..502613a 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -1841,6 +1841,149 @@ strict_aliasing_warning (tree otype, tree type, tree expr)
   return false;
 }
 
+/* Warn about memset (&a, 0, sizeof (&a)); and similar mistakes with
+   sizeof as last operand of certain builtins.  */
+
+void
+sizeof_pointer_memaccess_warning (location_t loc, tree callee,
+				  VEC(tree, gc) *params, tree sizeof_arg,
+				  bool (*comp_types) (tree, tree))
+{
+  tree type, dest = NULL_TREE, src = NULL_TREE, tem;
+  bool strop = false;
+
+  if (TREE_CODE (callee) != FUNCTION_DECL
+      || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
+      || sizeof_arg == error_mark_node
+      || VEC_length (tree, params) <= 1)
+    return;
+
+  type = TYPE_P (sizeof_arg) ? sizeof_arg : TREE_TYPE (sizeof_arg);
+  if (!POINTER_TYPE_P (type))
+    return;
+
+  switch (DECL_FUNCTION_CODE (callee))
+    {
+    case BUILT_IN_STRNCMP:
+    case BUILT_IN_STRNCASECMP:
+    case BUILT_IN_STRNCPY:
+    case BUILT_IN_STRNCAT:
+      strop = true;
+      /* FALLTHRU */
+    case BUILT_IN_MEMCPY:
+    case BUILT_IN_MEMMOVE:
+    case BUILT_IN_MEMCMP:
+      if (VEC_length (tree, params) < 3)
+	return;
+      src = VEC_index (tree, params, 1);
+      dest = VEC_index (tree, params, 0);
+      break;
+    case BUILT_IN_MEMSET:
+      if (VEC_length (tree, params) < 3)
+	return;
+      dest = VEC_index (tree, params, 0);
+      break;
+    case BUILT_IN_STRNDUP:
+      src = VEC_index (tree, params, 0);
+      strop = true;
+      break;
+    default:
+      break;
+    }
+
+  if (dest
+      && (tem = tree_strip_nop_conversions (dest))
+      && POINTER_TYPE_P (TREE_TYPE (tem))
+      && comp_types (TREE_TYPE (TREE_TYPE (tem)), type))
+    return;
+
+  if (src
+      && (tem = tree_strip_nop_conversions (src))
+      && POINTER_TYPE_P (TREE_TYPE (tem))
+      && comp_types (TREE_TYPE (TREE_TYPE (tem)), type))
+    return;
+
+  if (dest)
+    {
+      if (!TYPE_P (sizeof_arg)
+	  && operand_equal_p (dest, sizeof_arg, 0)
+	  && comp_types (TREE_TYPE (dest), type))
+	{
+	  if (TREE_CODE (sizeof_arg) == ADDR_EXPR && !strop)
+	    warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+			"argument to %<sizeof%> in %qD call is the same "
+			"expression as the destination; did you mean to "
+			"remove the addressof?", callee);
+	  else if ((TYPE_PRECISION (TREE_TYPE (type))
+		    == TYPE_PRECISION (char_type_node))
+		   || strop)
+	    warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+			"argument to %<sizeof%> in %qD call is the same "
+			"expression as the destination; did you mean to "
+			"provide an explicit length?", callee);
+	  else
+	    warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+			"argument to %<sizeof%> in %qD call is the same "
+			"expression as the destination; did you mean to "
+			"dereference it?", callee);
+	  return;
+	}
+
+      if (POINTER_TYPE_P (TREE_TYPE (dest))
+	  && !strop
+	  && comp_types (TREE_TYPE (dest), type)
+	  && !VOID_TYPE_P (TREE_TYPE (type)))
+	{
+	  warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+		      "argument to %<sizeof%> in %qD call is the same "
+		      "pointer type %qT as the destination; expected %qT "
+		      "or an explicit length", callee, TREE_TYPE (dest),
+		      TREE_TYPE (TREE_TYPE (dest)));
+	  return;
+	}
+    }
+
+  if (src)
+    {
+      if (!TYPE_P (sizeof_arg)
+	  && operand_equal_p (src, sizeof_arg, 0)
+	  && comp_types (TREE_TYPE (src), type))
+	{
+	  if (TREE_CODE (sizeof_arg) == ADDR_EXPR && !strop)
+	    warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+			"argument to %<sizeof%> in %qD call is the same "
+			"expression as the source; did you mean to "
+			"remove the addressof?", callee);
+	  else if ((TYPE_PRECISION (TREE_TYPE (type))
+		    == TYPE_PRECISION (char_type_node))
+		   || strop)
+	    warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+			"argument to %<sizeof%> in %qD call is the same "
+			"expression as the source; did you mean to "
+			"provide an explicit length?", callee);
+	  else
+	    warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+			"argument to %<sizeof%> in %qD call is the same "
+			"expression as the source; did you mean to "
+			"dereference it?", callee);
+	  return;
+	}
+
+      if (POINTER_TYPE_P (TREE_TYPE (src))
+	  && !strop
+	  && comp_types (TREE_TYPE (src), type)
+	  && !VOID_TYPE_P (TREE_TYPE (type)))
+	{
+	  warning_at (loc, OPT_Wsizeof_pointer_memaccess,
+		      "argument to %<sizeof%> in %qD call is the same "
+		      "pointer type %qT as the source; expected %qT "
+		      "or an explicit length", callee, TREE_TYPE (src),
+		      TREE_TYPE (TREE_TYPE (src)));
+	  return;
+	}
+    }
+}
+
 /* Warn for unlikely, improbable, or stupid DECL declarations
    of `main'.  */
 
diff --git a/gcc/c-family/c-common.def b/gcc/c-family/c-common.def
index 2a7df88..b6df9a3 100644
--- a/gcc/c-family/c-common.def
+++ b/gcc/c-family/c-common.def
@@ -2,7 +2,7 @@
    additional tree codes used in the GNU C compiler (see tree.def
    for the standard codes).
    Copyright (C) 1987, 1988, 1990, 1993, 1997, 1998,
-   1999, 2000, 2001, 2004, 2005, 2007, 2009, 2010
+   1999, 2000, 2001, 2004, 2005, 2007, 2009, 2010, 2011, 2012
    Free Software Foundation, Inc.
    Written by Benjamin Chelf <chelf@codesourcery.com>
 
@@ -53,6 +53,10 @@ DEFTREECODE (EXCESS_PRECISION_EXPR, "excess_precision_expr", tcc_expression, 1)
    number.  */
 DEFTREECODE (USERDEF_LITERAL, "userdef_literal", tcc_exceptional, 3)
 
+/* Represents a 'sizeof' expression during C++ template expansion,
+   or for the purpose of -Wsizeof-pointer-memaccess warning.  */
+DEFTREECODE (SIZEOF_EXPR, "sizeof_expr", tcc_expression, 1)
+
 /*
 Local variables:
 mode:c
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 050112e..9298e3d 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1,6 +1,6 @@
 /* Definitions for c-common.c.
-   Copyright (C) 1987, 1993, 1994, 1995, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
+   Copyright (C) 1987, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001, 2002,
+   2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011, 2012
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -768,6 +768,9 @@ extern tree fix_string_type (tree);
 extern void constant_expression_warning (tree);
 extern void constant_expression_error (tree);
 extern bool strict_aliasing_warning (tree, tree, tree);
+extern void sizeof_pointer_memaccess_warning (location_t, tree,
+					      VEC(tree, gc) *, tree,
+					      bool (*) (tree, tree));
 extern void warnings_for_convert_and_check (tree, tree, tree);
 extern tree convert_and_check (tree, tree);
 extern void overflow_warning (location_t, tree);
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 2fa59dc..29121b5 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -1,6 +1,6 @@
 /* C/ObjC/C++ command line option handling.
-   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
-   Free Software Foundation, Inc.
+   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011,
+   2012 Free Software Foundation, Inc.
    Contributed by Neil Booth.
 
 This file is part of GCC.
@@ -374,6 +374,7 @@ c_common_handle_option (size_t scode, const char *arg, int value,
       warn_return_type = value;
       warn_sequence_point = value;	/* Was C only.  */
       warn_switch = value;
+      warn_sizeof_pointer_memaccess = value;
       if (warn_strict_aliasing == -1)
 	set_Wstrict_aliasing (&global_options, value);
       warn_address = value;
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 981b7ab..914d110 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -474,6 +474,9 @@ Wmissing-field-initializers
 C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Warning EnabledBy(Wextra)
 Warn about missing fields in struct initializers
 
+Wsizeof-pointer-memaccess
+C ObjC C++ ObjC++ Var(warn_sizeof_pointer_memaccess) Warning
+
 Wsuggest-attribute=format
 C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
 Warn about functions which might be candidates for format attributes