llvm dev - Jan 2017 - [cfe-dev] Modernizing LLVM Coding Style Guide and enforcing Clang-tidy

2017-01-09 19:25 GMT+01:00 Mehdi Amini <mehdi.amini at apple.com>:
>
> On Jan 9, 2017, at 10:20 AM, Reid Kleckner via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> On Mon, Jan 9, 2017 at 7:25 AM, Piotr Padlewski via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> 2017-01-09 16:15 GMT+01:00 Renato Golin <renato.golin at
linaro.org>:
>>
>>> On 9 January 2017 at 14:17, Piotr Padlewski via cfe-dev
>>> <cfe-dev at lists.llvm.org> wrote:
>>> > - prefer "using' instead of "typedef"
>>> > - use default member initialization
>>> > - use default, override, delete
>>> > - skip "virtual" with override
>>>
>>> I thought we had all of those already...
>>>
>>> Nope, some people use it, but I still see a lot of new code with
>> typedefs.
>> I would like to have it written in style guide so it will be easier to
>> convince to change in review.
>>
>
> The last two are enforced by compiler warnings now. The second is hard
> because of bitfields.
>
> I object to the first. If you need a new type name, use a typedef. It's
> time honored and everyone, including C programmers, will know what
you're
> doing. I don't understand why people push the new thing just for the
sake
> of new-ness.
>
>
> `using` handles strictly more cases than  `typedef`, in particular partial
> specialization of templates. So because we’ll end up with `using` anyway,
> uniformity can be valuable. So that could be a motivation: since `using` is
> needed anyway, might be better to just use it always (I’m not saying it is
> a “strong” motivation though, just some piece of rational).
> (I also find that typedef of function pointers in particular are terrible,
> and `using` is much better for these, but that can be a matter of taste).
>
> —
> Mehdi
>
+1 Exactly this.
I don't think C programmer will not understand using. The "="
makes it much
simpler to read, even if it is the first time you see it, which is not the
case of typedef.

typedef MyType::NestedType (*fptr)(const MyOhterType&);
or
using fptr = MyType::NestedType (*)(const MyOhterType&);

Typedefs with function pointers are used in couple of places in LLVM and I
find it terible to read.

So it is not about new-ness. Trust me, I would never use typedef if using
was first :)
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On Mon, Jan 9, 2017 at 10:31 AM, Piotr Padlewski via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
>
> 2017-01-09 19:25 GMT+01:00 Mehdi Amini <mehdi.amini at apple.com>:
>>
>>
>> On Jan 9, 2017, at 10:20 AM, Reid Kleckner via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>
>> On Mon, Jan 9, 2017 at 7:25 AM, Piotr Padlewski via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>>
>>> 2017-01-09 16:15 GMT+01:00 Renato Golin <renato.golin at
linaro.org>:
>>>>
>>>> On 9 January 2017 at 14:17, Piotr Padlewski via cfe-dev
>>>> <cfe-dev at lists.llvm.org> wrote:
>>>> > - prefer "using' instead of "typedef"
>>>> > - use default member initialization
>>>> > - use default, override, delete
>>>> > - skip "virtual" with override
>>>>
>>>> I thought we had all of those already...
>>>>
>>> Nope, some people use it, but I still see a lot of new code with
>>> typedefs.
>>> I would like to have it written in style guide so it will be easier
to
>>> convince to change in review.
>>
>>
>> The last two are enforced by compiler warnings now. The second is hard
>> because of bitfields.
>>
>> I object to the first. If you need a new type name, use a typedef.
It's
>> time honored and everyone, including C programmers, will know what
you're
>> doing. I don't understand why people push the new thing just for
the sake of
>> new-ness.
>>
>>
>> `using` handles strictly more cases than  `typedef`, in particular
partial
>> specialization of templates. So because we’ll end up with `using`
anyway,
>> uniformity can be valuable. So that could be a motivation: since
`using` is
>> needed anyway, might be better to just use it always (I’m not saying it
is a
>> “strong” motivation though, just some piece of rational).
>> (I also find that typedef of function pointers in particular are
terrible,
>> and `using` is much better for these, but that can be a matter of
taste).
>>
>> —
>> Mehdi
>
>
> +1 Exactly this.
> I don't think C programmer will not understand using. The "="
makes it much
> simpler to read, even if it is the first time you see it, which is not the
> case of typedef.
>
> typedef MyType::NestedType (*fptr)(const MyOhterType&);
> or
> using fptr = MyType::NestedType (*)(const MyOhterType&);
I would prefer using typedefs at least for function pointers.  I find either of

Hi,

Sorry I fat fingered an earlier send in the previous email.  I was
trying to say:

On Mon, Jan 9, 2017 at 2:52 PM, Sanjoy Das
<sanjoy at playingwithpointers.com> wrote:
>> +1 Exactly this.
>> I don't think C programmer will not understand using. The
"=" makes it much
>> simpler to read, even if it is the first time you see it, which is not
the
>> case of typedef.
>>
>> typedef MyType::NestedType (*fptr)(const MyOhterType&);
>> or
>> using fptr = MyType::NestedType (*)(const MyOhterType&);
>
I would prefer to please keep using typedefs at least for function
pointers.  I find either of

typedef MyType::NestedType (*fptr)(const MyOhterType&);

or

typedef int fptr(const int&);

void f(fptr* ptr) {
  ...
}

easier to read than the "using" declaration (especially the second
form, with the explicit `fptr* ptr`).

-- Sanjoy