[llvm-dev] RFC: changing variable naming rules in LLVM codebase

Rui Ueyama via llvm-dev llvm-dev at lists.llvm.org
Wed Jul 10 04:24:02 PDT 2019 

Good point, too. I believe I can find lines starting with `@parameter` and
apply the same name conversion rules to identifiers after `@parameter`.
Since lld doesn't use doxygen comments, it is fine for now, but before
moving forward, I'll address that. Thank you for pointing that out.

On Wed, Jul 10, 2019 at 8:20 PM Alex Brachet-Mialot <
alexbrachetmialot at gmail.com> wrote:

> Also, now that I think about it, I believe doxygen will fail to build if
> the @parameter comments aren't changed to match the new names, my guess is
> it case sensitive. So perhaps we will need to find a way to manually change
> these names for doxygen comments?
>
> On Wed, Jul 10, 2019 at 7:12 AM Alex Brachet-Mialot <
> alexbrachetmialot at gmail.com> wrote:
>
>> Rui,
>>
>> I have created D64474 to change comments explicitly stating the parameter
>> names for constants ( /*parameterName=*/<constant> ). I did this by hand to
>> match the new variable names. Do you know if there would be a way to update
>> these comments with a tool similar to what you used to change these names?
>> Perhaps it would be much more difficult, I'm guessing clang's AST doesn't
>> have a way to describe comments? It's obviously not a huge deal to have
>> these changed it could be done over time.
>>
>> Best,
>> Alex
>>
>> On Wed, Jul 10, 2019 at 12:18 AM Rui Ueyama via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hi Joan,
>>>
>>> On Tue, Jul 9, 2019 at 9:46 PM Joan Lluch <joan.lluch at icloud.com> wrote:
>>>
>>>> Hi Rui,
>>>>
>>>> I’m totally positive on switching to camelCase convention. In fact I
>>>> have been always uncomfortable with the current naming approach.
>>>>
>>>> My only suggestion/concern is that we should provide a transition path
>>>> not only for the trunk code in the repository, but for eventual
>>>> out-of-trunk code with implementations of custom architectures. I have
>>>> currently a custom backend implemented on top of LLVM 9 and therefore this
>>>> change will surely break my code. I assume that developers affected by this
>>>> will be able to run the converting tools to fix their own code.
>>>>
>>>
>>> The tool that I wrote for lld's style conversion should work for
>>> out-of-trunk code, so as I described in the previous email, third-party
>>> code maintainer should be able to use the tool to convert the style first
>>> in their repositories and then rebase in order to avoid large merge
>>> conflicts.
>>>
>>> The tool needs to be polished to convert other subprojects such as
>>> clang, but I'll keep your request in mind. I'll try my best to provide a
>>> smooth transition path for out-of-trunk code for any change that I'll
>>> submit for the style change.
>>>
>>> John
>>>>
>>>> On 9 Jul 2019, at 09:23, Rui Ueyama via llvm-dev <
>>>> llvm-dev at lists.llvm.org> wrote:
>>>>
>>>> Thanks, Chris.
>>>>
>>>> Looks like everybody is at least mildly comfortable with my variable
>>>> name renaming change, so I'll to submit that change to lld subdirectory
>>>> soon. If you have any objections, please let me know. Note that this is not
>>>> the end of my effort but actually the beginning of it. As Chris said, I
>>>> believe we should do this to the entire LLVM codebase. I'm planning to do
>>>> that directory-by-directory basis.
>>>>
>>>> On Tue, Jul 9, 2019 at 2:03 PM Chris Lattner <clattner at nondot.org>
>>>> wrote:
>>>>
>>>>> This looks really great to me Rui, and I’m also pleased to see the
>>>>> positive comments on the review thread.  Thank you for driving this forward!
>>>>>
>>>>> -Chris
>>>>>
>>>>>
>>>>> On Jul 4, 2019, at 9:50 PM, Rui Ueyama <ruiu at google.com> wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I wrote a tool <https://reviews.llvm.org/D64123> to batch-rename
>>>>> variable names so that they are in camelCase, and I applied the tool to lld
>>>>> subdirectory. You can see my change at https://reviews.llvm.org/D64121.
>>>>> If you have any comments, please reply.
>>>>>
>>>>> If people are happy about this change, I can do the same thing for
>>>>> other directories including LLVM itself and Clang.
>>>>>
>>>>> On Mon, Jun 10, 2019 at 6:34 PM Rui Ueyama <ruiu at google.com> wrote:
>>>>>
>>>>>> On Mon, Jun 10, 2019 at 6:27 PM Michael Platings <
>>>>>> Michael.Platings at arm.com> wrote:
>>>>>>
>>>>>>> Hi Rui,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> As per the provisional plan [1] we’re still at step 1: improving git
>>>>>>> blame. The status of this is that there are some fairly mature patches in
>>>>>>> the Git project’s queue [2], and I’m hopeful that it will be accepted in
>>>>>>> something close to its current form.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> But if you can get started on steps 2 & 3 i.e. making forks
>>>>>>> available with the possible changes applied then that would be great. My
>>>>>>> hope is that once everyone can see what the options really look like then
>>>>>>> it will be easier to reach consensus.
>>>>>>>
>>>>>>
>>>>>> Sure, I'll try to do that. I'll probably start with finding
>>>>>> identifiers and typenames that will conflict after the naming scheme change
>>>>>> and rename them so that they won't conflict. The number of such symbols
>>>>>> would hopefully be small, and submitting such renaming changes wouldn't be
>>>>>> distracting. After that, I think I can create a mechanical change to rename
>>>>>> variables to see how it will look like.
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> -Michael
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> [1]
>>>>>>> https://llvm.org/docs/Proposals/VariableNames.html#provisional-plan
>>>>>>>
>>>>>>> [2]
>>>>>>> https://public-inbox.org/git/20190515214503.77162-8-brho@google.com/T/
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> *From:* Rui Ueyama <ruiu at google.com>
>>>>>>> *Sent:* 07 June 2019 08:42
>>>>>>> *To:* Chris Lattner <clattner at nondot.org>
>>>>>>> *Cc:* Michael Platings <Michael.Platings at arm.com>;
>>>>>>> llvm-dev at lists.llvm.org; nd <nd at arm.com>
>>>>>>> *Subject:* Re: [llvm-dev] RFC: changing variable naming rules in
>>>>>>> LLVM codebase
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> This thread is not active for a while, but I'm still interested in
>>>>>>> seeing a change.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Reading through this thread, looks like we can agree that we want to
>>>>>>> change the local variable naming scheme so that they start with a lowercase
>>>>>>> letter. Besides that, there were discussions about lower_case, camelCase,
>>>>>>> m_ prefix, and each argument seems as convincing as others. I'm not sure
>>>>>>> what is the decision making process in a situation like this.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I'd personally vote for changing local variables to start with a
>>>>>>> lowercase letter and keep other naming conventions as-is to make it a
>>>>>>> minimum change.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> As I stated before, I'm happy to make a change to lld to see how a
>>>>>>> naming convention change will look like, but in order to do that I need to
>>>>>>> get at least a rough consensus to do that. What is a way to proceed?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Sat, May 25, 2019 at 3:00 PM Chris Lattner via llvm-dev <
>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>>
>>>>>>> Hi Michael,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I’m still very interested in seeing a change here.  If someone is
>>>>>>> interested in seeing a codebase using the proposed camelBack convention for
>>>>>>> variables names, the MLIR codebase is public
>>>>>>> <https://github.com/tensorflow/mlir> and uses it.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> If you’re curious to see what this looks like in practice, there are
>>>>>>> lots of examples in the codebase, here is an example .cpp file
>>>>>>> <https://github.com/tensorflow/mlir/blob/master/lib/Transforms/LoopUnrollAndJam.cpp>
>>>>>>> , here is another
>>>>>>> <https://github.com/tensorflow/mlir/blob/master/lib/Parser/Parser.cpp>,
>>>>>>> here is an example header
>>>>>>> <https://github.com/tensorflow/mlir/blob/master/include/mlir/IR/Location.h>
>>>>>>> .
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> We are still working our way through open sourcing logistics (not
>>>>>>> all the code is out yet), but we would still like to contribute at least
>>>>>>> parts of this to LLVM if the project is interested.  [[This is just an FYI,
>>>>>>> not itself a proposal yet - one will be coming when we’re ready.]]
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> -Chris
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On May 21, 2019, at 3:01 AM, Michael Platings via llvm-dev <
>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Hi folks,
>>>>>>>
>>>>>>> Git is on its way to learning how to ignore commits, allowing us to
>>>>>>> do variable renaming and other small refactorings without breaking git
>>>>>>> blame.
>>>>>>>
>>>>>>> It's like git-hyper-blame [1] but significantly more powerful as it
>>>>>>> uses fuzzy matching to match lines, including lines that may have been
>>>>>>> split or joined.
>>>>>>>
>>>>>>> A preview release of Git with this new feature is at:
>>>>>>> https://github.com/mplatings/git/releases/tag/ignore-rev
>>>>>>>
>>>>>>> Some of you have told me that you already have to spend time running
>>>>>>> git blame multiple times to look past uninteresting commits so I'd love for
>>>>>>> you to give this feature a try and see if it helps you. Your feedback will
>>>>>>> be very valuable.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> -Michael
>>>>>>>
>>>>>>> [1]
>>>>>>> https://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/git-hyper-blame.html
>>>>>>> _______________________________________________
>>>>>>> LLVM Developers mailing list
>>>>>>> llvm-dev at lists.llvm.org
>>>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
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>>>>>>>
>>>>>>>
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>>
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