Re: [PATCH] Make -Wint-in-bool-context warn on suspicious shift ops

[Bernd Edlinger]

On 10/08/16 19:40, Jason Merrill wrote:
> On Fri, Sep 30, 2016 at 1:07 AM, Bernd Edlinger
> <bernd.edlin...@hotmail.de> wrote:
>> On 09/29/16 22:38, Jason Merrill wrote:
>>> On Thu, Sep 29, 2016 at 3:58 PM, Bernd Edlinger
>>> <bernd.edlin...@hotmail.de> wrote:
>>>> Unfortunately, without that exception there is a false positive:
>>>>
>>>> In file included from ../../gcc-trunk/gcc/ada/gcc-interface/decl.c:30:0:
>>>> ../../gcc-trunk/gcc/ada/gcc-interface/decl.c: In function 'int
>>>> adjust_packed(tree, tree, int)':
>>>> ../../gcc-trunk/gcc/tree.h:1874:22: error: << on signed integer in
>>>> boolean context [-Werror=int-in-bool-context]
>>>>          ? ((unsigned)1) << ((NODE)->type_common.align - 1) : 0)
>>>>            ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> Ah, this issue again: the shift isn't in boolean context, it's in
>>> integer context.  I think we want to be a lot more conservative about
>>> these warnings in the arms of a COND_EXPR.  In fact, I think the
>>> entire
>>>
>>>         /* Distribute the conversion into the arms of a COND_EXPR.  */
>>>
>>> section is wrong now that we're doing delayed folding.
>>
>> Could you take care of this ?
>
> Done thus:
>

Thanks.

But I have one question:

--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -2253,6 +2253,15 @@ cp_fold (tree x)
        op1 = cp_fold (TREE_OPERAND (x, 1));
        op2 = cp_fold (TREE_OPERAND (x, 2));

+      if (TREE_CODE (TREE_TYPE (x)) == BOOLEAN_TYPE)
+       {
+         warning_sentinel (warn_int_in_bool_context);


Yes, it compiles, but ...
how can this compile at all?

Doesn't it miss a name of a local?
like warning_sentinel c (warn_int_in_bool_context);

If I disassemble this function I see a constructor of
warning_sentinel directly followed by a destuctor.

And apparently warn_int_in_bool_context is not zero
in the block, thus:

       if (TREE_CODE (TREE_TYPE (x)) == BOOLEAN_TYPE)
        {
          warning_sentinel (warn_int_in_bool_context);
          gcc_assert (!warn_int_in_bool_context);
          if (!VOID_TYPE_P (TREE_TYPE (op1)))
            op1 = cp_truthvalue_conversion (op1);


fails the assertion.


Bernd.