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re PR c++/24745 (unpleasant warning for "if (NULL)")

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2007-01-30  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR c++/24745
	* doc/invoke.texi (Wpointer-arith): Document warning.

cp/
	* typeck.c (build_binary_op): Fix logic for warning. Move warning
	to -Wpointer-arith.
	* call.c (convert_like_real): Don't warn when converting to
	boolean type.

testsuite/
	* g++.dg/warn/null4.C: New.

From-SVN: r121361
This commit is contained in:
Manuel López-Ibáñez 2007-01-30 22:29:11 +00:00
parent 14734fc701
commit b9edb4b11c
7 changed files with 65 additions and 19 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2007-01-30 Manuel Lopez-Ibanez <manu@gcc.gnu.org>
PR c++/24745
* doc/invoke.texi (Wpointer-arith): Document warning.
2007-01-30 Janis Johnson
* doc/extend.texi (Decimal Floating Types): Remove decfloat.h from

8
gcc/cp/ChangeLog
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@ -1,3 +1,11 @@
2007-01-30 Manuel Lopez-Ibanez <manu@gcc.gnu.org>
PR c++/24745
* typeck.c (build_binary_op): Fix logic for warning. Move warning
to -Wpointer-arith.
* call.c (convert_like_real): Don't warn when converting to
boolean type.
2007-01-29 Manuel Lopez-Ibanez <manu@gcc.gnu.org>
* decl.c (pop_label): Replace warning with call to

2
gcc/cp/call.c
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@ -4250,7 +4250,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
tree t = non_reference (totype);
/* Issue warnings about peculiar, but valid, uses of NULL. */
if (ARITHMETIC_TYPE_P (t) && expr == null_node)
if (expr == null_node && TREE_CODE (t) != BOOLEAN_TYPE && ARITHMETIC_TYPE_P (t))
{
if (fn)
warning (OPT_Wconversion, "passing NULL to non-pointer argument %P of %qD",

32
gcc/cp/typeck.c
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@ -3828,30 +3828,28 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
}
}
/* If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
Then the expression will be built.
It will be given type FINAL_TYPE if that is nonzero;
otherwise, it will be given type RESULT_TYPE. */
/* Issue warnings about peculiar, but valid, uses of NULL. */
if (/* It's reasonable to use pointer values as operands of &&
if ((orig_op0 == null_node || orig_op1 == null_node)
/* It's reasonable to use pointer values as operands of &&
and ||, so NULL is no exception. */
!(code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
&& (/* If OP0 is NULL and OP1 is not a pointer, or vice versa. */
(orig_op0 == null_node
&& TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)
/* Or vice versa. */
|| (orig_op1 == null_node
&& TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
/* Or, both are NULL and the operation was not a comparison. */
|| (orig_op0 == null_node && orig_op1 == null_node
&& code != EQ_EXPR && code != NE_EXPR)))
&& code != TRUTH_ANDIF_EXPR && code != TRUTH_ORIF_EXPR
&& ( /* Both are NULL (or 0) and the operation was not a comparison. */
(null_ptr_cst_p (orig_op0) && null_ptr_cst_p (orig_op1)
&& code != EQ_EXPR && code != NE_EXPR)
/* Or if one of OP0 or OP1 is neither a pointer nor NULL. */
|| (!null_ptr_cst_p (orig_op0) && TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
|| (!null_ptr_cst_p (orig_op1) && TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)))
/* Some sort of arithmetic operation involving NULL was
performed. Note that pointer-difference and pointer-addition
have already been handled above, and so we don't end up here in
that case. */
warning (0, "NULL used in arithmetic");
warning (OPT_Wpointer_arith, "NULL used in arithmetic");
/* If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
Then the expression will be built.
It will be given type FINAL_TYPE if that is nonzero;
otherwise, it will be given type RESULT_TYPE. */
if (! converted)
{
if (TREE_TYPE (op0) != result_type)

3
gcc/doc/invoke.texi
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@ -3153,7 +3153,8 @@ such assumptions.
Warn about anything that depends on the ``size of'' a function type or
of @code{void}. GNU C assigns these types a size of 1, for
convenience in calculations with @code{void *} pointers and pointers
to functions.
to functions. In C++, warn also when an arithmetic operation involves
@code{NULL}. This warning is also enabled by @option{-pedantic}.
@item -Wbad-function-cast @r{(C only)}
@opindex Wbad-function-cast

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2007-01-30 Manuel Lopez-Ibanez <manu@gcc.gnu.org>
PR c++/24745
* g++.dg/warn/null4.C: New.
2001-01-30 Roger Sayle <roger@eyesopen.com>
Uros Bizjak <ubizjak@gmail.com>

29
gcc/testsuite/g++.dg/warn/null4.C Normal file
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@ -0,0 +1,29 @@
// PR c++/24745 : warnings for NULL constant.
// { dg-do compile }
// { dg-options "-Wpointer-arith -Wconversion " }
#include <cstddef>
int foo (void)
{
if (NULL == 1) return -1; // { dg-warning "NULL used in arithmetic" }
if (NULL > NULL) return -1; // { dg-warning "NULL used in arithmetic" }
if (NULL < NULL) return -1; // { dg-warning "NULL used in arithmetic" }
if (NULL >= 0) return -1; // { dg-warning "NULL used in arithmetic" }
if (NULL <= 0) return -1; // { dg-warning "NULL used in arithmetic" }
return 0;
}
int bar (void)
{
if (NULL) return -1;
if (!NULL) return -1;
if (!NULL == 1) return -1;
if (NULL || NULL) return -1;
if (!NULL && NULL) return -1;
if (NULL == NULL) return -1;
if (NULL != NULL) return -1;
if (NULL == 0) return -1;
if (NULL != 0) return -1;
return 0;
}