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re PR c/32061 ((Wlogical-op) wording of warning of constant logicials need improvement)

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2009-04-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c/32061
	PR c++/36954
	* doc/invoke.texi: Add -Wlogical-op to -Wextra.
	* common.opt (Wlogical-op): Move from here...
	* c.opt (Wlogical-op): ... to here.
	* c-typeck.c (parser_build_binary_op): Update call to
	warn_logical_operator.
	* c-opts.c (c_common_post_options): Enable warn_logical_op with
	extra_warnings.
	* c-common.c (warn_logical_op): Update.
	* c-common.h (warn_logical_op): Update declaration.
cp/
	* call.c (build_new_op): Save the original codes of operands
	before folding.
	
testsuite/
	* gcc.dg/pr32061.c: New.
	* gcc.dg/Wlogical-op-1.c: Update.
	* g++.dg/warn/Wlogical-op-1.C: Update.
	* g++.dg/warn/pr36954.C: New.

From-SVN: r146344
This commit is contained in:
Manuel López-Ibáñez 2009-04-19 11:04:13 +00:00
parent c93c8cf442
commit ca409efd92
15 changed files with 195 additions and 66 deletions
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14
gcc/ChangeLog
View File

@ -1,3 +1,17 @@
2009-04-19 Manuel López-Ibáñez <manu@gcc.gnu.org>
PR c/32061
PR c++/36954
* doc/invoke.texi: Add -Wlogical-op to -Wextra.
* common.opt (Wlogical-op): Move from here...
* c.opt (Wlogical-op): ... to here.
* c-typeck.c (parser_build_binary_op): Update call to
warn_logical_operator.
* c-opts.c (c_common_post_options): Enable warn_logical_op with
extra_warnings.
* c-common.c (warn_logical_op): Update.
* c-common.h (warn_logical_op): Update declaration.
2009-04-19 Eric Botcazou <ebotcazou@adacore.com>
* tree.c (protected_set_expr_location): Fix formatting.

61
gcc/c-common.c
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@ -1712,38 +1712,43 @@ overflow_warning (tree value)
}
}
/* Warn about use of a logical || / && operator being used in a
context where it is likely that the bitwise equivalent was intended
by the programmer. CODE is the TREE_CODE of the operator, ARG1
and ARG2 the arguments. */
/* Warn about uses of logical || / && operator in a context where it
is likely that the bitwise equivalent was intended by the
programmer. We have seen an expression in which CODE is a binary
operator used to combine expressions OP_LEFT and OP_RIGHT, which
before folding had CODE_LEFT and CODE_RIGHT. */
void
warn_logical_operator (enum tree_code code, tree arg1, tree
arg2)
warn_logical_operator (location_t location, enum tree_code code,
enum tree_code code_left, tree op_left,
enum tree_code ARG_UNUSED (code_right), tree op_right)
{
switch (code)
if (code != TRUTH_ANDIF_EXPR
&& code != TRUTH_AND_EXPR
&& code != TRUTH_ORIF_EXPR
&& code != TRUTH_OR_EXPR)
return;
/* Warn if &&/|| are being used in a context where it is
likely that the bitwise equivalent was intended by the
programmer. That is, an expression such as op && MASK
where op should not be any boolean expression, nor a
constant, and mask seems to be a non-boolean integer constant. */
if (!truth_value_p (code_left)
&& INTEGRAL_TYPE_P (TREE_TYPE (op_left))
&& !CONSTANT_CLASS_P (op_left)
&& !TREE_NO_WARNING (op_left)
&& TREE_CODE (op_right) == INTEGER_CST
&& !integer_zerop (op_right)
&& !integer_onep (op_right))
{
case TRUTH_ANDIF_EXPR:
case TRUTH_ORIF_EXPR:
case TRUTH_OR_EXPR:
case TRUTH_AND_EXPR:
if (!TREE_NO_WARNING (arg1)
&& INTEGRAL_TYPE_P (TREE_TYPE (arg1))
&& !CONSTANT_CLASS_P (arg1)
&& TREE_CODE (arg2) == INTEGER_CST
&& !integer_zerop (arg2))
{
warning (OPT_Wlogical_op,
"logical %<%s%> with non-zero constant "
"will always evaluate as true",
((code == TRUTH_ANDIF_EXPR)
|| (code == TRUTH_AND_EXPR)) ? "&&" : "||");
TREE_NO_WARNING (arg1) = true;
}
break;
default:
break;
if (code == TRUTH_ORIF_EXPR || code == TRUTH_OR_EXPR)
warning_at (location, OPT_Wlogical_op, "logical %<or%>"
" applied to non-boolean constant");
else
warning_at (location, OPT_Wlogical_op, "logical %<and%>"
" applied to non-boolean constant");
TREE_NO_WARNING (op_left) = true;
}
}

3
gcc/c-common.h
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@ -801,7 +801,8 @@ extern bool strict_aliasing_warning (tree, tree, tree);
extern void warnings_for_convert_and_check (tree, tree, tree);
extern tree convert_and_check (tree, tree);
extern void overflow_warning (tree);
extern void warn_logical_operator (enum tree_code, tree, tree);
extern void warn_logical_operator (location_t, enum tree_code,
enum tree_code, tree, enum tree_code, tree);
extern void check_main_parameter_types (tree decl);
extern bool c_determine_visibility (tree);
extern bool same_scalar_type_ignoring_signedness (tree, tree);

2
gcc/c-opts.c
View File

@ -1080,6 +1080,8 @@ c_common_post_options (const char **pfilename)
warn_override_init = extra_warnings;
if (warn_ignored_qualifiers == -1)
warn_ignored_qualifiers = extra_warnings;
if (warn_logical_op == -1)
warn_logical_op = extra_warnings;
/* -Wpointer-sign is disabled by default, but it is enabled if any
of -Wall or -pedantic are given. */

5
gcc/c-typeck.c
View File

@ -2925,8 +2925,9 @@ parser_build_binary_op (location_t location, enum tree_code code,
if (warn_parentheses)
warn_about_parentheses (code, code1, arg1.value, code2, arg2.value);
if (TREE_CODE_CLASS (code1) != tcc_comparison)
warn_logical_operator (code, arg1.value, arg2.value);
if (warn_logical_op)
warn_logical_operator (input_location, code,
code1, arg1.value, code2, arg2.value);
/* Warn about comparisons against string literals, with the exception
of testing for equality or inequality of a string literal with NULL. */

4
gcc/c.opt
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@ -284,6 +284,10 @@ Winvalid-pch
C ObjC C++ ObjC++ Warning
Warn about PCH files that are found but not used
Wlogical-op
C ObjC C++ ObjC++ Var(warn_logical_op) Init(-1) Warning
Warn when a logical operator is suspiciously always evaluating to true or false
Wlong-long
C ObjC C++ ObjC++ Var(warn_long_long) Init(1) Warning
Do not warn about using \"long long\" when -pedantic

4
gcc/common.opt
View File

@ -128,10 +128,6 @@ Wlarger-than=
Common RejectNegative Joined UInteger Warning
-Wlarger-than=<number> Warn if an object is larger than <number> bytes
Wlogical-op
Common Warning Var(warn_logical_op)
Warn when a logical operator is suspicously always evaluating to true or false
Wunsafe-loop-optimizations
Common Var(warn_unsafe_loop_optimizations) Warning
Warn if the loop cannot be optimized due to nontrivial assumptions.

7
gcc/cp/ChangeLog
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@ -1,3 +1,10 @@
2009-04-19 Manuel López-Ibáñez <manu@gcc.gnu.org>
PR c/32061
PR c++/36954
* call.c (build_new_op): Save the original codes of operands
before folding.
2009-04-18 Kazu Hirata <kazu@codesourcery.com>
* cp-tree.h: Remove the prototype for insert_block.

28
gcc/cp/call.c
View File

@ -3897,11 +3897,12 @@ build_new_op (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
tree result = NULL_TREE;
bool result_valid_p = false;
enum tree_code code2 = NOP_EXPR;
enum tree_code code_orig_arg1 = ERROR_MARK;
enum tree_code code_orig_arg2 = ERROR_MARK;
conversion *conv;
void *p;
bool strict_p;
bool any_viable_p;
bool expl_eq_arg1 = false;
if (error_operand_p (arg1)
|| error_operand_p (arg2)
@ -3935,8 +3936,10 @@ build_new_op (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
case TRUTH_ANDIF_EXPR:
case TRUTH_AND_EXPR:
case TRUTH_OR_EXPR:
if (COMPARISON_CLASS_P (arg1))
expl_eq_arg1 = true;
/* These are saved for the sake of warn_logical_operator. */
code_orig_arg1 = TREE_CODE (arg1);
code_orig_arg2 = TREE_CODE (arg2);
default:
break;
}
@ -4140,8 +4143,16 @@ build_new_op (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
if (conv->kind == ck_ref_bind)
conv = conv->u.next;
arg1 = convert_like (conv, arg1, complain);
if (arg2)
{
/* We need to call warn_logical_operator before
converting arg2 to a boolean_type. */
if (complain & tf_warning)
warn_logical_operator (input_location, code,
code_orig_arg1, arg1,
code_orig_arg2, arg2);
conv = cand->convs[1];
if (conv->kind == ck_ref_bind)
conv = conv->u.next;
@ -4155,12 +4166,6 @@ build_new_op (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
arg3 = convert_like (conv, arg3, complain);
}
if (!expl_eq_arg1)
{
if (complain & tf_warning)
warn_logical_operator (code, arg1, arg2);
expl_eq_arg1 = true;
}
}
}
@ -4185,8 +4190,9 @@ build_new_op (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
case TRUTH_ORIF_EXPR:
case TRUTH_AND_EXPR:
case TRUTH_OR_EXPR:
if (!expl_eq_arg1)
warn_logical_operator (code, arg1, arg2);
warn_logical_operator (input_location, code,
code_orig_arg1, arg1, code_orig_arg2, arg2);
/* Fall through. */
case PLUS_EXPR:
case MINUS_EXPR:
case MULT_EXPR:

4
gcc/doc/invoke.texi
View File

@ -2804,6 +2804,7 @@ name is still supported, but the newer name is more descriptive.)
@gccoptlist{-Wclobbered @gol
-Wempty-body @gol
-Wignored-qualifiers @gol
-Wlogical-op @gol
-Wmissing-field-initializers @gol
-Wmissing-parameter-type @r{(C only)} @gol
-Wold-style-declaration @r{(C only)} @gol
@ -3790,7 +3791,8 @@ programmer intended to use @code{strcmp}. This warning is enabled by
@opindex Wno-logical-op
Warn about suspicious uses of logical operators in expressions.
This includes using logical operators in contexts where a
bit-wise operator is likely to be expected.
bit-wise operator is likely to be expected. This warning is enabled by
@option{-Wextra}.
@item -Waggregate-return
@opindex Waggregate-return

9
gcc/testsuite/ChangeLog
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@ -1,3 +1,12 @@
2009-04-19 Manuel López-Ibáñez <manu@gcc.gnu.org>
PR c/32061
PR c++/36954
* gcc.dg/pr32061.c: New.
* gcc.dg/Wlogical-op-1.c: Update.
* g++.dg/warn/Wlogical-op-1.C: Update.
* g++.dg/warn/pr36954.C: New.
2009-04-18 Joseph Myers <joseph@codesourcery.com>
PR c/27676

33
gcc/testsuite/g++.dg/warn/Wlogical-op-1.C
View File

@ -28,20 +28,39 @@ extern testenum testa();
void foo()
{
if ( f && b2 ) // { dg-warning "always evaluate as" }
if ( f && b2 ) // { dg-warning "logical" }
do_something(1);
if ( c && b2 ) // { dg-warning "always evaluate as" }
if ( c && b2 ) // { dg-warning "logical" }
do_something(2);
if ( b2 && c == a ) // { dg-bogus "always evaluate as" }
if ( b2 && c == a ) // { dg-bogus "logical" }
do_something(101);
if ( 1 && c )
do_something(102); // { dg-bogus "always evaluate as" }
if ( t2 && b2 ) // { dg-bogus "always evaluate as" }
do_something(102); // { dg-bogus "logical" }
if ( t2 && b2 ) // { dg-bogus "logical" }
do_something(103);
if ( true && c == a ) // { dg-bogus "always evaluate as" }
if ( true && c == a ) // { dg-bogus "logical" }
do_something(104);
if ( b2 && true ) // { dg-bogus "always evaluate as" }
if ( b2 && true ) // { dg-bogus "logical" }
do_something(105);
}
void bar()
{
if ( f || b2 ) // { dg-warning "logical" }
do_something(1);
if ( c || b2 ) // { dg-warning "logical" }
do_something(2);
if ( b2 || c == a ) // { dg-bogus "logical" }
do_something(101);
if ( 1 || c )
do_something(102); // { dg-bogus "logical" }
if ( t2 || b2 ) // { dg-bogus "logical" }
do_something(103);
if ( true || c == a ) // { dg-bogus "logical" }
do_something(104);
if ( b2 || true ) // { dg-bogus "logical" }
do_something(105);
}

23
gcc/testsuite/g++.dg/warn/pr36954.C Normal file
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@ -0,0 +1,23 @@
// PR c++/36954
// { dg-do compile }
// { dg-options "-Wlogical-op -Wextra -Wall" }
template<class C> void Test()
{
if ((1 == 2) || (true)) {
}
if ((1 == 2) || (!false)) {
}
if (false || true) {
}
}
int main() {
if ((1 == 2) || (true)) {
}
}

54
gcc/testsuite/gcc.dg/Wlogical-op-1.c
View File

@ -14,34 +14,64 @@ extern int testa();
void foo()
{
if ( testa() && b ) /* { dg-warning "always evaluate as" } */
if ( testa() && b ) /* { dg-warning "logical" } */
(void)testa();
if ( c && b ) /* { dg-warning "always evaluate as" } */
if ( c && b ) /* { dg-warning "logical" } */
(void)testa();
if ( c && 0x42 ) /* { dg-warning "always evaluate as" } */
if ( c && 0x42 ) /* { dg-warning "logical" } */
(void)testa();
if ( c && 0x42 ) /* { dg-warning "always evaluate as" } */
(void) testa();
if ( c && 0x80 >>6) /* { dg-warning "always evaluate as" } */
if ( c && 0x80 >>6) /* { dg-warning "logical" } */
(void)testa();
if ( b && c == a ) /* { dg-bogus "always evaluate as" } */
if ( b && c == a ) /* { dg-bogus "logical" } */
(void)testa();
if ( 1 && c ) /* { dg-bogus "always evaluate as" } */
if ( 1 && c ) /* { dg-bogus "logical" } */
(void)testa();
if ( t2 && b ) /* { dg-bogus "always evaluate as" } */
if ( t2 && b ) /* { dg-bogus "logical" } */
(void)testa();
if ( 0 && c == a ) /* { dg-bogus "always evaluate as" } */
if ( 0 && c == a ) /* { dg-bogus "logical" } */
(void)testa();
if ( b && 1 ) /* { dg-bogus "always evaluate as" } */
if ( b && 1 ) /* { dg-bogus "logical" } */
(void)testa();
}
void bar()
{
if ( testa() || b ) /* { dg-warning "logical" } */
(void)testa();
if ( c || b ) /* { dg-warning "logical" } */
(void)testa();
if ( c || 0x42 ) /* { dg-warning "logical" } */
(void) testa();
if ( c || 0x80 >>6) /* { dg-warning "logical" } */
(void)testa();
if ( b || c == a ) /* { dg-bogus "logical" } */
(void)testa();
if ( 1 || c ) /* { dg-bogus "logical" } */
(void)testa();
if ( t2 || b ) /* { dg-bogus "logical" } */
(void)testa();
if ( 0 || c == a ) /* { dg-bogus "logical" } */
(void)testa();
if ( b || 1 ) /* { dg-bogus "logical" } */
(void)testa();
}

10
gcc/testsuite/gcc.dg/pr32061.c Normal file
View File

@ -0,0 +1,10 @@
/* PR c/32061
{ dg-do compile }
{ dg-options "-Wlogical-op -Wall -Wextra" }
*/
#define FORCE 1
#define FLAG 1
int func (int resp, int flags)
{
return (resp && (FORCE || (FLAG & flags)));
}