[cfe-dev] [GSoC][clang] Bash completion for clang project

[Richard Smith via cfe-dev]

On 5 June 2017 at 17:01, Rui Ueyama <ruiu at google.com> wrote:

> On Tue, Jun 6, 2017 at 8:37 AM, Richard Smith <richard at metafoo.co.uk>
> wrote:
>
>> On 5 June 2017 at 08:41, Rui Ueyama <ruiu at google.com> wrote:
>>
>>> On Thu, Jun 1, 2017 at 2:02 PM, Richard Smith via cfe-dev <
>>> cfe-dev at lists.llvm.org> wrote:
>>>
>>>> On 31 May 2017 at 06:21, Yuka Takahashi via cfe-dev <
>>>> cfe-dev at lists.llvm.org> wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> My name is Yuka Takahshi and I would like to ask few questions
>>>>> regarding to GSoC project : bash-autocompletion for clang.
>>>>> We are now trying to build flag completions for which we call "value".
>>>>> Eg. in -std=c++11, c++11 is a "value", and in
>>>>> -analyzer-checker=alpha.cplusplus, alpha.cplusplus is a "value".
>>>>>
>>>>> We are planning to implement most of the code in OptTable.cpp, in
>>>>> order to reuse OptTable, which is generated by Options.inc.
>>>>> Options.inc is generated via Tablegen from Options.td, so we are
>>>>> planning to add the information of values into Options.td.
>>>>>
>>>>> I would like to ask for a advice regarding how to implement the flag
>>>>> like "-std=" and "-analyzer-checker=".
>>>>> These flags are unique because their value information are already in
>>>>> LangStandards.def for "-std=", and Checkers.td for "-analyzer-checker=".
>>>>> We are thinking to reuse these information and add these information
>>>>> to Options.inc, so that we can handle the flag completion in unified manner.
>>>>> This way of implementation has further benefits from this GSoC
>>>>> project, because from this we can make documentation more simply and reduce
>>>>> custom handling of each value and code duplication.
>>>>>
>>>>> The problem is that, we are not sure what is the best way for this
>>>>> implementaion.
>>>>> For flags which are not like "-std=" and "-analyzer-checker=", we
>>>>> decided to add a class to hold the value information in Options.td. Eg. for
>>>>> "-stdlib=", ArgValues<"libc++, libstdc++, platform">.
>>>>> So we are looking for how to generate something like "libc++,
>>>>> libstdc++, platform" from LangStandards.def and Checkers.td for "-std=" and
>>>>> "-analyzer-checker=".
>>>>>
>>>>
>>>> One way to do this would be to rewrite LangStandards.def as a .td file,
>>>> and extend clang-tblgen to generate something like the current .def file
>>>> from that .td file. Then you can include LangStandards.td into Options.td
>>>> and somehow specify that all of the LangStandard records define possible
>>>> values for the -std= flag. (You could use something like
>>>> ArgValueClass<"LangStandard"> for this case, ArgValueClass<"Checker"> for
>>>> -analyzer-checker=, and so on. Your tablegen backend is able to do
>>>> arbitrary queries over the tablegen records, so there are a variety of ways
>>>> to express this.)
>>>>
>>>> Similar things can be done for other options that take values from .def
>>>> files, such as -fsanitize= (Basic/Sanitizers.def).
>>>>
>>>
>>> I don't know if rewriting LangStandards.def just for shell
>>> autocompletion is worth the effort, unless there's other reason to do that.
>>> It seems you can define LANGSTANDARD macro before including this file to
>>> get a list of all possible language options. You can use that information
>>> to return all possible options when `-std=<tab>` is hit, can't you?
>>>
>>
>> You can, but we don't run the C preprocessor on tablegen files, which
>> means you couldn't generate this data from tablegen without some auxiliary
>> work. We also want the "valid values" data for generated help text and
>> command-line argument summary documentation; it's not only desired for tab
>> completion.
>>
>
> Are you saying that you want to have the "valid values" data not only for
> "-std=" and a few other options but for all options such as
> -flto={thin,full} or -fopenmp={libomp,libgomp,libiomp}?
>

Ideally, yes, we'd have the "valid values" data for all options that have a
(small) enumerated set of options, for tab-completion, referemce
documentation, and any other similar use cases that people might have (UI
for configuring compiler flags?).
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