Re: [Xen-devel] [PATCH v4 4/4] build: enable no-parentheses in clang

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.02.17 at 15:13, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 14/02/17 14:06, Roger Pau Monne wrote:
>> On Tue, Feb 14, 2017 at 06:56:12AM -0700, Jan Beulich wrote:
>>>>>> On 14.02.17 at 13:30, <roger.pau@xxxxxxxxxx> wrote:
>>>> --- a/Config.mk
>>>> +++ b/Config.mk
>>>> @@ -212,9 +212,6 @@ CFLAGS += -std=gnu99
>>>>  
>>>>  CFLAGS += -Wall -Wstrict-prototypes
>>>>  
>>>> -# Clang complains about macros that expand to 'if ( ( foo == bar ) ) ...'
>>>> -CFLAGS-$(clang) += -Wno-parentheses
>>> Taking the comment being removed here together with ....
>>>
>>>> --- a/xen/arch/x86/traps.c
>>>> +++ b/xen/arch/x86/traps.c
>>>> @@ -2011,7 +2011,7 @@ uint32_t guest_io_read(unsigned int port, unsigned 
>>>> int bytes,
>>>>          {
>>>>              sub_data = pv_pit_handler(port, 0, 0);
>>>>          }
>>>> -        else if ( (port == RTC_PORT(0)) )
>>>> +        else if ( port == RTC_PORT(0) )
>>>>          {
>>>>              sub_data = currd->arch.cmos_idx;
>>>>          }
>>>> @@ -2080,7 +2080,7 @@ void guest_io_write(unsigned int port, unsigned int 
>>>> bytes, uint32_t data,
>>>>          {
>>>>              pv_pit_handler(port, (uint8_t)data, 1);
>>>>          }
>>>> -        else if ( (port == RTC_PORT(0)) )
>>>> +        else if ( port == RTC_PORT(0) )
>>>>          {
>>>>              currd->arch.cmos_idx = data;
>>>>          }
>>> ... the code adjustments all being to other than macros I wonder
>>> whether in the version you use the issue is no longer being
>>> reported in macro expansions, but older clang still chokes on such.
>>> Or did you go check that we have no such uses left (which seems
>>> unlikely to me)?
>> I assume that in recent versions of clang this is no longer an issue. Travis
>> tests with clang 3.5 and I test with 3.8, and none of them find any issues.
>> IMHO we should turn it on because I barely doubt anyone is building Xen with
>> older versions of clang, when I started working on this the clang support was
>> completely bitrotted.
> 
> There was some Clang 3.2 support in the past, but it had completely
> bitrotten.
> 
> Clang 3.5 is our documented minimum, so I think it is reasonable to take
> these clobbers out, seeing as they are not needed.

Okay, if the minimum version was tested, then I'm fine with the
adjustment.

Jan


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