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re PR c/49706 (No warning for (!x > 1) which is always false) 

PR c/49706
	* doc/invoke.texi: Document -Wlogical-not-parentheses.
c-family/
	* c-common.c (warn_logical_not_parentheses): New function.
	* c-common.h (warn_logical_not_parentheses): Declare.
	* c.opt (Wlogical-not-parentheses): New option.
c/
	* c-typeck.c (parser_build_binary_op): Warn when logical not is used
	on the left hand side operand of a comparison. 
cp/
	* parser.c (cp_parser_binary_expression): Warn when logical not is
	used on the left hand side operand of a comparison.
testsuite/
	* c-c++-common/pr49706.c: New test.

From-SVN: r211255
This commit is contained in:
Marek Polacek 2014-06-05 06:20:05 +00:00 committed by Marek Polacek
parent 6447c55dea
commit 742938c911
12 changed files with 191 additions and 2 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/49706
* doc/invoke.texi: Document -Wlogical-not-parentheses.
2014-06-04 Tom de Vries <tom@codesourcery.com>
* config/s390/s390.md ("addptrdi3", "addptrsi3"): Use INTVAL only on

7
gcc/c-family/ChangeLog
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@ -1,3 +1,10 @@
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/49706
* c-common.c (warn_logical_not_parentheses): New function.
* c-common.h (warn_logical_not_parentheses): Declare.
* c.opt (Wlogical-not-parentheses): New option.
2014-06-04 Marek Polacek <polacek@redhat.com>
PR c/30020

23
gcc/c-family/c-common.c
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@ -1722,6 +1722,29 @@ warn_logical_operator (location_t location, enum tree_code code, tree type,
}
}
/* Warn about logical not used on the left hand side operand of a comparison.
This function assumes that the LHS is inside of TRUTH_NOT_EXPR.
Do not warn if the LHS or RHS is of a boolean or a vector type. */
void
warn_logical_not_parentheses (location_t location, enum tree_code code,
tree lhs, tree rhs)
{
if (TREE_CODE_CLASS (code) != tcc_comparison)
return;
if (TREE_TYPE (lhs) == NULL_TREE
|| TREE_TYPE (rhs) == NULL_TREE)
;
else if (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE
|| TREE_CODE (TREE_TYPE (rhs)) == BOOLEAN_TYPE
|| VECTOR_TYPE_P (TREE_TYPE (lhs))
|| VECTOR_TYPE_P (TREE_TYPE (rhs)))
return;
warning_at (location, OPT_Wlogical_not_parentheses,
"logical not is only applied to the left hand side of "
"comparison");
}
/* Warn if EXP contains any computations whose results are not used.
Return true if a warning is printed; false otherwise. LOCUS is the

2
gcc/c-family/c-common.h
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@ -772,6 +772,8 @@ extern void overflow_warning (location_t, tree);
extern bool warn_if_unused_value (const_tree, location_t);
extern void warn_logical_operator (location_t, enum tree_code, tree,
enum tree_code, tree, enum tree_code, tree);
extern void warn_logical_not_parentheses (location_t, enum tree_code, tree,
tree);
extern void check_main_parameter_types (tree decl);
extern bool c_determine_visibility (tree);
extern bool vector_types_compatible_elements_p (tree, tree);

4
gcc/c-family/c.opt
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@ -490,6 +490,10 @@ Wlogical-op
C ObjC C++ ObjC++ Var(warn_logical_op) Init(0) Warning
Warn when a logical operator is suspiciously always evaluating to true or false
Wlogical-not-parentheses
C ObjC C++ ObjC++ Var(warn_logical_not_paren) Warning
Warn when logical not is used on the left hand side operand of a comparison
Wlong-long
C ObjC C++ ObjC++ Var(warn_long_long) Init(-1) Warning
Do not warn about using \"long long\" when -pedantic

6
gcc/c/ChangeLog
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@ -1,3 +1,9 @@
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/49706
* c-typeck.c (parser_build_binary_op): Warn when logical not is used
on the left hand side operand of a comparison.
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/48062

4
gcc/c/c-typeck.c
View File

@ -3401,6 +3401,10 @@ parser_build_binary_op (location_t location, enum tree_code code,
warn_logical_operator (location, code, TREE_TYPE (result.value),
code1, arg1.value, code2, arg2.value);
if (warn_logical_not_paren
&& code1 == TRUTH_NOT_EXPR)
warn_logical_not_parentheses (location, code, arg1.value, arg2.value);
/* Warn about comparisons against string literals, with the exception
of testing for equality or inequality of a string literal with NULL. */
if (code == EQ_EXPR || code == NE_EXPR)

6
gcc/cp/ChangeLog
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@ -1,3 +1,9 @@
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/49706
* parser.c (cp_parser_binary_expression): Warn when logical not is
used on the left hand side operand of a comparison.
2014-06-04 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/43453

7
gcc/cp/parser.c
View File

@ -7883,6 +7883,8 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
enum tree_code rhs_type;
enum cp_parser_prec new_prec, lookahead_prec;
tree overload;
bool parenthesized_not_lhs_warn
= cp_lexer_next_token_is (parser->lexer, CPP_NOT);
/* Parse the first expression. */
current.lhs = cp_parser_cast_expression (parser, /*address_p=*/false,
@ -7985,6 +7987,11 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
else if (current.tree_type == TRUTH_ORIF_EXPR)
c_inhibit_evaluation_warnings -= current.lhs == truthvalue_true_node;
if (warn_logical_not_paren
&& parenthesized_not_lhs_warn)
warn_logical_not_parentheses (current.loc, current.tree_type,
TREE_OPERAND (current.lhs, 0), rhs);
overload = NULL;
/* ??? Currently we pass lhs_type == ERROR_MARK and rhs_type ==
ERROR_MARK for everything that is not a binary expression.

22
gcc/doc/invoke.texi
View File

@ -256,7 +256,7 @@ Objective-C and Objective-C++ Dialects}.
-Winit-self -Winline -Wmaybe-uninitialized @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
-Winvalid-pch -Wlarger-than=@var{len} -Wunsafe-loop-optimizations @gol
-Wlogical-op -Wlong-long @gol
-Wlogical-op -Wlogical-not-parentheses -Wlong-long @gol
-Wmain -Wmaybe-uninitialized -Wmissing-braces -Wmissing-field-initializers @gol
-Wmissing-include-dirs @gol
-Wno-multichar -Wnonnull -Wno-overflow -Wopenmp-simd @gol
@ -3856,7 +3856,7 @@ expression to a type other than @code{bool}. For example:
@group
switch ((int) (a == 4))
@{
...
@dots{}
@}
@end group
@end smallexample
@ -4704,6 +4704,24 @@ 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.
@item -Wlogical-not-parentheses
@opindex Wlogical-not-parentheses
@opindex Wno-logical-not-parentheses
Warn about logical not used on the left hand side operand of a comparison.
This option does not warn if the LHS or RHS operand is of a boolean or
a vector type. Its purpose is to detect suspicious code like the following:
@smallexample
int a;
@dots{}
if (!a > 1) @{ @dots{} @}
@end smallexample
It is possible to suppress the warning by wrapping the LHS into
parentheses:
@smallexample
if ((!a) > 1) @{ @dots{} @}
@end smallexample
@item -Waggregate-return
@opindex Waggregate-return
@opindex Wno-aggregate-return

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/49706
* c-c++-common/pr49706.c: New test.
2014-06-05 Marek Polacek <polacek@redhat.com>
PR c/48062

102
gcc/testsuite/c-c++-common/pr49706.c Normal file
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@ -0,0 +1,102 @@
/* PR c/49706 */
/* { dg-do compile } */
/* { dg-options "-Wlogical-not-parentheses" } */
#ifndef __cplusplus
#define bool _Bool
#endif
enum E { A, B };
bool b;
extern enum E foo_e (void);
extern bool foo_b (void);
extern int foo_i (void);
#ifdef __cplusplus
template <class T, class U> bool f1(T t, U u) { return (!t == u); } /* { dg-warning "logical not is only applied to the left hand side of comparison" "" { target c++ } 15 } */
template <class T, class U> bool f2(T t, U u) { return ((!t) == u); }
template <class T, class U> bool f3(T t, U u) { return (!g(t) == u); } /* { dg-warning "logical not is only applied to the left hand side of comparison" "" { target c++ } 17 } */
template <class T, class U> bool f4(T t, U u) { return ((!g(t)) == u); }
#endif
void
fn1 (int i1, int i2, bool b1, bool b2)
{
b = !i1 == i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !i1 != i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !i1 < i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !i1 > i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !i1 <= i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !i1 >= i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = i1 == i2;
b = i1 != i2;
b = i1 < i2;
b = i1 > i2;
b = i1 <= i2;
b = i1 >= i2;
/* Parens suppress the warning. */
b = (!i1) == i2;
b = (!i1) != i2;
b = (!i1) < i2;
b = (!i1) > i2;
b = (!i1) <= i2;
b = (!i1) >= i2;
/* ...but not these parens. */
b = (!i1 == i2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = (!i1 != i2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = (!i1 < i2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = (!i1 > i2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = (!i1 <= i2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = (!i1 >= i2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !b1 == b2;
b = !b1 != b2;
b = !b1 < b2;
b = !b1 > b2;
b = !b1 <= b2;
b = !b1 >= b2;
b = !foo_i () == i1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = (!foo_i ()) == i1;
b = !foo_b () == b1;
b = !!i1 == i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !!i1 != i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !!i1 < i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !!i1 > i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !!i1 <= i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !!i1 >= i2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !!foo_i () == i1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
/* Be careful here. */
b = (i1 == 0) != 0;
b = (i1 == 0) == 0;
b = (i1 != 0) != 0;
b = (i1 != 0) == 0;
}
void
fn2 (enum E e)
{
b = e == B;
b = e == foo_e ();
b = foo_e () == A;
b = foo_e () == foo_e ();
b = !e == A; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !e == foo_e (); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !foo_e () == A; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !foo_e () == foo_e (); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
b = !(e == A);
b = !(e == foo_e ());
b = !(foo_e () == A);
b = !(foo_e () == foo_e ());
b = (!e) == A;
b = (!e) == foo_e ();
b = (!foo_e ()) == A;
b = (!foo_e ()) == foo_e ();
}