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[C/C++ PATCH] -Wlogical-not-parentheses tweaks (PR c/65120)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>, Jason Merrill <jason at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 20 Feb 2015 01:03:26 +0100
- Subject: [C/C++ PATCH] -Wlogical-not-parentheses tweaks (PR c/65120)
- Authentication-results: sourceware.org; auth=none
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
As reported, !!x == y is quite common in the Linux kernel
and unlike the !x == y case it usually doesn't mean mistyped
!(x == y) or x != y. clang++ apparently doesn't warn about that
either, and it doesn't warn even about the case where ! is applied
to a bool. As the argument is already folded, it isn't easy to determine
those cases always, but I hope the following is sufficient until we switch
to late folding.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2015-02-19 Jakub Jelinek <jakub@redhat.com>
PR c/65120
* c-typeck.c (parser_build_binary_op): Don't warn for
!!x == y or !b == y where b is _Bool.
* parser.c (cp_parser_binary_expression): Don't warn for
!!x == y or !b == y where b is bool.
* c-c++-common/pr49706.c: Adjust tests for not warning
about !!x == y or !b == y where b is boolean, and add
some further tests.
* c-c++-common/pr62199-2.c: Likewise.
--- gcc/c/c-typeck.c.jj 2015-02-09 22:19:53.000000000 +0100
+++ gcc/c/c-typeck.c 2015-02-19 22:35:38.522781551 +0100
@@ -3460,8 +3460,34 @@ parser_build_binary_op (location_t locat
if (warn_logical_not_paren
&& code1 == TRUTH_NOT_EXPR
- && code2 != TRUTH_NOT_EXPR)
- warn_logical_not_parentheses (location, code, arg2.value);
+ && code2 != TRUTH_NOT_EXPR
+ /* Avoid warning for !!x == y. */
+ && (TREE_CODE (arg1.value) != NE_EXPR
+ || !integer_zerop (TREE_OPERAND (arg1.value, 1))))
+ {
+ /* Avoid warning for !b == y where b has _Bool type. */
+ tree t = integer_zero_node;
+ if (TREE_CODE (arg1.value) == EQ_EXPR
+ && integer_zerop (TREE_OPERAND (arg1.value, 1))
+ && TREE_TYPE (TREE_OPERAND (arg1.value, 0)) == integer_type_node)
+ {
+ t = TREE_OPERAND (arg1.value, 0);
+ do
+ {
+ if (TREE_TYPE (t) != integer_type_node)
+ break;
+ if (TREE_CODE (t) == C_MAYBE_CONST_EXPR)
+ t = C_MAYBE_CONST_EXPR_EXPR (t);
+ else if (CONVERT_EXPR_P (t))
+ t = TREE_OPERAND (t, 0);
+ else
+ break;
+ }
+ while (1);
+ }
+ if (TREE_CODE (TREE_TYPE (t)) != BOOLEAN_TYPE)
+ warn_logical_not_parentheses (location, code, arg2.value);
+ }
/* Warn about comparisons against string literals, with the exception
of testing for equality or inequality of a string literal with NULL. */
--- gcc/cp/parser.c.jj 2015-02-14 00:19:49.000000000 +0100
+++ gcc/cp/parser.c 2015-02-19 22:04:19.059604707 +0100
@@ -8270,7 +8270,20 @@ cp_parser_binary_expression (cp_parser*
c_inhibit_evaluation_warnings -= current.lhs == truthvalue_true_node;
if (warn_logical_not_paren
- && current.lhs_type == TRUTH_NOT_EXPR)
+ && current.lhs_type == TRUTH_NOT_EXPR
+ /* Avoid warning for !!x == y. */
+ && (TREE_CODE (current.lhs) != NE_EXPR
+ || !integer_zerop (TREE_OPERAND (current.lhs, 1)))
+ && (TREE_CODE (current.lhs) != TRUTH_NOT_EXPR
+ || (TREE_CODE (TREE_OPERAND (current.lhs, 0)) != TRUTH_NOT_EXPR
+ /* Avoid warning for !b == y where b is boolean. */
+ && (TREE_TYPE (TREE_OPERAND (current.lhs, 0)) == NULL_TREE
+ || (TREE_CODE (TREE_TYPE (TREE_OPERAND (current.lhs, 0)))
+ != BOOLEAN_TYPE))))
+ /* Avoid warning for !!b == y where b is boolean. */
+ && (!DECL_P (current.lhs)
+ || TREE_TYPE (current.lhs) == NULL_TREE
+ || TREE_CODE (TREE_TYPE (current.lhs)) != BOOLEAN_TYPE))
warn_logical_not_parentheses (current.loc, current.tree_type, rhs);
overload = NULL;
--- gcc/testsuite/c-c++-common/pr49706.c.jj 2014-06-06 09:19:20.000000000 +0200
+++ gcc/testsuite/c-c++-common/pr49706.c 2015-02-19 20:53:27.466594656 +0100
@@ -12,10 +12,13 @@ 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); }
+template <class T, class U> bool tfn1(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 tfn2(T t, U u) { return ((!t) == u); }
+template <class T, class U> bool tfn3(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 tfn4(T t, U u) { return ((!g(t)) == u); }
+template <class T, class U> bool tfn5(T t, U u) { return (!!t == u); } /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+template <class T, class U> bool tfn6(T t, U u) { return (!!g(t) == u); } /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+template <int N> bool tfn7(int i1, int i2) { return (!i1 == i2); } /* { dg-warning "logical not is only applied to the left hand side of comparison" "" { target c++ } 21 } */
#endif
void
@@ -58,23 +61,42 @@ fn1 (int i1, int i2, bool b1, bool b2)
b = !b1 <= b2;
b = !b1 >= b2;
+ b = !b1 == i2;
+ b = !b1 != i2;
+ b = !b1 < i2;
+ b = !b1 > i2;
+ b = !b1 <= i2;
+ b = !b1 >= i2;
+
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" } */
+ b = !!i1 == i2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 != i2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 < i2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 > i2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 <= i2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 >= i2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!foo_i () == i1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+
+ b = !!b1 == i2;
+ b = !!b1 != i2;
+ b = !!b1 < i2;
+ b = !!b1 > i2;
+ b = !!b1 <= i2;
+ b = !!b1 >= i2;
/* Be careful here. */
b = (i1 == 0) != 0;
b = (i1 == 0) == 0;
b = (i1 != 0) != 0;
b = (i1 != 0) == 0;
+
+ b = !5 == 4; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !!5 == 4; /* { dg-bogus "logical not is only applied to the left hand side of comparison" "" { xfail *-*-* } } */
+ b = !1 == 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !!1 == 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" "" { xfail *-*-* } } */
}
void
@@ -100,3 +122,44 @@ fn2 (enum E e)
b = (!foo_e ()) == A;
b = (!foo_e ()) == foo_e ();
}
+
+void
+fn3 (int i1, float f2)
+{
+ b = !i1 == f2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !i1 != f2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !i1 < f2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !i1 > f2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !i1 <= f2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = !i1 >= f2; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+
+ b = i1 == f2;
+ b = i1 != f2;
+ b = i1 < f2;
+ b = i1 > f2;
+ b = i1 <= f2;
+ b = i1 >= f2;
+
+ /* Parens suppress the warning. */
+ b = (!i1) == f2;
+ b = (!i1) != f2;
+ b = (!i1) < f2;
+ b = (!i1) > f2;
+ b = (!i1) <= f2;
+ b = (!i1) >= f2;
+
+ /* ...but not these parens. */
+ b = (!i1 == f2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = (!i1 != f2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = (!i1 < f2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = (!i1 > f2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = (!i1 <= f2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ b = (!i1 >= f2); /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+
+ b = !!i1 == f2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 != f2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 < f2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 > f2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 <= f2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ b = !!i1 >= f2; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+}
--- gcc/testsuite/c-c++-common/pr62199-2.c.jj 2014-09-01 09:43:39.000000000 +0200
+++ gcc/testsuite/c-c++-common/pr62199-2.c 2015-02-20 00:57:07.362564155 +0100
@@ -11,10 +11,10 @@ bool r;
void
foo (bool b)
{
- r = !b == 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
- r = !b != 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
- r = !b > 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
- r = !b >= 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
- r = !b < 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
- r = !b <= 1; /* { dg-warning "logical not is only applied to the left hand side of comparison" } */
+ r = !b == 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ r = !b != 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ r = !b > 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ r = !b >= 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ r = !b < 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
+ r = !b <= 1; /* { dg-bogus "logical not is only applied to the left hand side of comparison" } */
}
Jakub