Hi,
Shall it a good idea to add new warning -Wsizeof-array-argument that
warns when sizeof is applied on parameter declared as an array ?
Similar to clang's -Wsizeof-array-argument:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20110613/042812.html
This was also reported as PR6940:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6940
I have attached a patch that adds the warning to C front-end.
I implemented it by adding a new member BOOL_BITFIELD is_array_parm to
tree_parm_decl. Not sure if that's a good approach.
Also should it be enabled by -Wall or -Wextra or only by
-Wsizeof-array-argument ?
Currently I have made it enabled by -Wall along with -Wsizeof-array-argument.
Bootstrapped on x86_64-unknown-linux-gnu.
[gcc]
* tree-core.h (tree_parm_decl): Add new member BOOL_BITFIELD is_array_parm
* tree.h (SET_PARM_DECL_IS_ARRAY): New macro.
(PARM_DECL_ARRAY_P): New macro.
[gcc/c]
* c-decl.c (push_parm_decl): Call SET_PARM_DECL_IS_ARRAY.
* c-typeck.c (c_expr_sizeof_expr): Add check for sizeof-array-argument warning.
[gcc/c-family]
* c.opt (-Wsizeof-array-argument): New option.
[gcc/testsuite/gcc.dg]
* sizeof-array-argument.c: New test-case.
Thanks and Regards,
Prathamesh
Index: gcc/tree-core.h
===================================================================
--- gcc/tree-core.h (revision 209800)
+++ gcc/tree-core.h (working copy)
@@ -1411,6 +1411,7 @@ struct GTY(()) tree_const_decl {
struct GTY(()) tree_parm_decl {
struct tree_decl_with_rtl common;
rtx incoming_rtl;
+ BOOL_BITFIELD is_array_parm;
};
struct GTY(()) tree_decl_with_vis {
Index: gcc/tree.h
===================================================================
--- gcc/tree.h (revision 209800)
+++ gcc/tree.h (working copy)
@@ -1742,6 +1742,7 @@ extern void protected_set_expr_location
#define TYPE_LANG_SPECIFIC(NODE) \
(TYPE_CHECK (NODE)->type_with_lang_specific.lang_specific)
+
#define TYPE_VALUES(NODE) (ENUMERAL_TYPE_CHECK (NODE)->type_non_common.values)
#define TYPE_DOMAIN(NODE) (ARRAY_TYPE_CHECK (NODE)->type_non_common.values)
#define TYPE_FIELDS(NODE) \
@@ -2258,6 +2259,12 @@ extern void decl_value_expr_insert (tree
#define DECL_INCOMING_RTL(NODE) \
(PARM_DECL_CHECK (NODE)->parm_decl.incoming_rtl)
+#define SET_PARM_DECL_IS_ARRAY(NODE, val) \
+ (PARM_DECL_CHECK (NODE)->parm_decl.is_array_parm = (val))
+
+#define PARM_DECL_ARRAY_P(NODE) \
+ (PARM_DECL_CHECK (NODE)->parm_decl.is_array_parm != 0)
+
/* Nonzero for a given ..._DECL node means that no warnings should be
generated just because this node is unused. */
#define DECL_IN_SYSTEM_HEADER(NODE) \
Index: gcc/c/c-decl.c
===================================================================
--- gcc/c/c-decl.c (revision 209800)
+++ gcc/c/c-decl.c (working copy)
@@ -4626,13 +4626,14 @@ push_parm_decl (const struct c_parm *par
{
tree attrs = parm->attrs;
tree decl;
+ int is_array;
decl = grokdeclarator (parm->declarator, parm->specs, PARM, false, NULL,
&attrs, expr, NULL, DEPRECATED_NORMAL);
decl_attributes (&decl, attrs, 0);
-
+ is_array = parm->declarator->kind == cdk_array;
+ SET_PARM_DECL_IS_ARRAY (decl, is_array);
decl = pushdecl (decl);
-
finish_decl (decl, input_location, NULL_TREE, NULL_TREE, NULL_TREE);
}
Index: gcc/c/c-typeck.c
===================================================================
--- gcc/c/c-typeck.c (revision 209800)
+++ gcc/c/c-typeck.c (working copy)
@@ -2730,6 +2730,12 @@ c_expr_sizeof_expr (location_t loc, stru
else
{
bool expr_const_operands = true;
+ if (warn_sizeof_array_argument && TREE_CODE (expr.value) == PARM_DECL && PARM_DECL_ARRAY_P (expr.value))
+ {
+ warning_at (loc, 0, "sizeof on array parameter %<%s%> shall return size of %qT",
+ IDENTIFIER_POINTER (DECL_NAME (expr.value)), expr.original_type);
+ inform (DECL_SOURCE_LOCATION (expr.value), "declared here");
+ }
tree folded_expr = c_fully_fold (expr.value, require_constant_value,
&expr_const_operands);
ret.value = c_sizeof (loc, TREE_TYPE (folded_expr));
Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt (revision 209800)
+++ gcc/c-family/c.opt (working copy)
@@ -509,6 +509,9 @@ Warn about missing fields in struct init
Wsizeof-pointer-memaccess
C ObjC C++ ObjC++ Var(warn_sizeof_pointer_memaccess) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
+Wsizeof-array-argument
+C Var(warn_sizeof_array_argument) Warning LangEnabledBy(C,Wall)
+
Wsuggest-attribute=format
C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
Warn about functions which might be candidates for format attributes
Index: gcc/testsuite/gcc.dg/sizeof-array-argument.c
===================================================================
--- gcc/testsuite/gcc.dg/sizeof-array-argument.c (revision 0)
+++ gcc/testsuite/gcc.dg/sizeof-array-argument.c (working copy)
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-Wsizeof-array-argument" } */
+
+int foo(int a[])
+{
+ return (int) sizeof (a); /* { dg-warning "sizeof on array parameter" } */
+}
+
+int bar(int x, int b[3])
+{
+ return x + (int) sizeof (b); /* { dg-warning "sizeof on array parameter" } */
+}
+
+int f(int *p)
+{
+ return (int) sizeof (*p);
+}
