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Re: [PATCH] Add a character size parameter to c_strlen/get_range_strlen
On 08/17/18 20:23, Martin Sebor wrote:
> On 08/17/2018 06:14 AM, Joseph Myers wrote:
>> On Fri, 17 Aug 2018, Jeff Law wrote:
>>
>>> On 08/16/2018 05:01 PM, Joseph Myers wrote:
>>>> On Thu, 16 Aug 2018, Jeff Law wrote:
>>>>
>>>>> restores previous behavior. The sprintf bits want to count element
>>>>> sized chunks, which for wchars is 4 bytes (that count will then be
>>>>
>>>>> /* Compute the range the argument's length can be in. */
>>>>> - fmtresult slen = get_string_length (arg);
>>>>> + int count_by = dir.specifier == 'S' || dir.modifier == FMT_LEN_l ? 4 : 1;
>>>>
>>>> I don't see how a hardcoded 4 is correct here. Surely you need to example
>>>> wchar_type_node to determine its actual size for this target.
>>> We did kick this around a little. IIRC Martin didn't think that it was
>>> worth handling the 2 byte wchar case.
>
> Sorry, I think we may have miscommunicated -- I didn't think it
> was useful to pass a size of the character type to the function.
> I agree that passing in a hardcoded constant doesn't seem right
> (even if GCC's wchar_t were always 4 bytes wide).
>
> I'm still not sure I see the benefit of passing in the expected
> element size given that the patch causes c_strlen() fail when
> the actual element size doesn't match ELTSIZE. If the caller
> asks for the number of bytes in a const wchar_t array it should
> get back the number bytes. (I could see it fail if the caller
> asked for the number of words in a char array whose size was
> not evenly divisible by wordsize.)
>
I think in this case c_strlen should use the type which the %S format
uses at runtime, otherwise it will not have anything to do with
the reality.
If the type is in fact the wrong, wide char type, we already
have a Wformat warning, therefore we should have the same
information here, that the Wformat warning has.
It can be something simple, like a global variable, that
is initialized somewhere in c-family to
TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT
and left at 0, for other languages.
Bernd.