On Wed, Aug 24, 2016 at 7:43 PM, Marek Polacek <pola...@redhat.com> wrote:
> The -Wlogical-not-parentheses deliberately doesn't warn when the RHS has
> boolean type. But since in C the type of a comparison is int, we need
> to check for tcc_comparison, too.
>
> Bootstrapped/regtested on x86_64-linux and ppc64le-redhat-linux, ok for trunk?
What about using truth_value_p ()? That also includes && and || (just
in case those
do not have boolean type).
Richard.
> 2016-08-24 Marek Polacek <pola...@redhat.com>
>
> PR c/77292
> * c-common.c (warn_logical_not_parentheses): Don't warn if RHS is
> a comparison.
>
> * c-c++-common/Wlogical-not-parentheses-1.c: New test.
>
> diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
> index 3feb910..47255c3 100644
> --- gcc/c-family/c-common.c
> +++ gcc/c-family/c-common.c
> @@ -1481,7 +1481,7 @@ warn_tautological_cmp (location_t loc, enum tree_code
> code, tree lhs, tree rhs)
>
> /* 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 RHS is of a boolean type. */
> + Do not warn if RHS is of a boolean type, or a comparison. */
>
> void
> warn_logical_not_parentheses (location_t location, enum tree_code code,
> @@ -1489,7 +1489,8 @@ warn_logical_not_parentheses (location_t location, enum
> tree_code code,
> {
> if (TREE_CODE_CLASS (code) != tcc_comparison
> || TREE_TYPE (rhs) == NULL_TREE
> - || TREE_CODE (TREE_TYPE (rhs)) == BOOLEAN_TYPE)
> + || TREE_CODE (TREE_TYPE (rhs)) == BOOLEAN_TYPE
> + || TREE_CODE_CLASS (TREE_CODE (rhs)) == tcc_comparison)
> return;
>
> /* Don't warn for !x == 0 or !y != 0, those are equivalent to
> diff --git gcc/testsuite/c-c++-common/Wlogical-not-parentheses-1.c
> gcc/testsuite/c-c++-common/Wlogical-not-parentheses-1.c
> index e69de29..4ae9ec2 100644
> --- gcc/testsuite/c-c++-common/Wlogical-not-parentheses-1.c
> +++ gcc/testsuite/c-c++-common/Wlogical-not-parentheses-1.c
> @@ -0,0 +1,18 @@
> +/* PR c/77292 */
> +/* { dg-do compile } */
> +/* { dg-options "-Wlogical-not-parentheses" } */
> +
> + /* Test that we don't warn if rhs is a comparison. */
> +
> +int
> +foo (int a, int b)
> +{
> + int r = 0;
> + r += !a == (a < b);
> + r += !a == (a > b);
> + r += !a == (a >= b);
> + r += !a == (a <= b);
> + r += !a == (a != b);
> + r += !a == (a == b);
> + return r;
> +}
>
> Marek
