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Re: [C/C++ PATCH] Implement -Wbool-compare (PR c++/62153)


On 18 August 2014 22:04, Marek Polacek <polacek@redhat.com> wrote:
> +void
> +maybe_warn_bool_compare (location_t loc, enum tree_code code, tree op0,
> +                        tree op1)
> +{
> +  if (TREE_CODE_CLASS (code) != tcc_comparison)
> +    return;
> +
> +  /* <boolean> CMP <cst> */
> +  if (TREE_CODE (op1) == INTEGER_CST
> +      && !integer_zerop (op1)
> +      && !integer_onep (op1))
> +    {
> +      if (code == EQ_EXPR
> +         || ((code == GT_EXPR || code == GE_EXPR)
> +             && tree_int_cst_sgn (op1) == 1)
> +         || ((code == LT_EXPR || code == LE_EXPR)
> +             && tree_int_cst_sgn (op1) == -1))
> +       warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
> +                   "with boolean expression is always false", op1);
> +      else
> +       warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
> +                   "with boolean expression is always true", op1);
> +    }
> +  /* <cst> CMP <boolean> */
> +  else if (TREE_CODE (op0) == INTEGER_CST
> +          && !integer_zerop (op0)
> +          && !integer_onep (op0))
> +    {
> +      if (code == EQ_EXPR
> +         || ((code == GT_EXPR || code == GE_EXPR)
> +             && tree_int_cst_sgn (op0) == -1)
> +         || ((code == LT_EXPR || code == LE_EXPR)
> +             && tree_int_cst_sgn (op0) == 1))
> +       warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
> +                   "with boolean expression is always false", op0);
> +      else
> +       warning_at (loc, OPT_Wbool_compare, "comparison of constant %qE "
> +                   "with boolean expression is always true", op0);
> +    }

Perhaps you can save some repetition by doing first:

tree op = (TREE_CODE (op1) == INTEGER_CST) ? op1 : op0;
if (TREE_CODE (op) == INTEGER_CST
    && !integer_zerop (op)

etc.

Cheers,

Manuel.


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