[cfe-dev] libclang's code completion APIs give unexpected results for Objective-C

[Michael Bolin]

Clarification: I misunderstood what -cc1 meant (
http://stackoverflow.com/questions/8991662/can-u-tell-me-what-does-the-clang-cc1-option-docleared
that up).

The following is a convenient way to test out the code completion API
without writing any code:

clang -cc1 -fsyntax-only -code-completion-at=PATH_TO_M_FILE:LINE:COL
PATH_TO_M_FILE



On Thu, Apr 24, 2014 at 10:35 AM, Michael Bolin <bolinfest at gmail.com> wrote:

> In case anyone else runs into this issue, this Stack Overflow post has a
> lot of helpful information:
> http://stackoverflow.com/questions/15875800/why-isnt-libclang-returning-meaningful-completion-results
> .
>
> In short, the line/column information that you pass should point to the
> start of the token, and it is the caller's responsibility to filter by the
> partially complete token.
>
> Also, clang has a flag (-code-completion-at) that makes it convenient to
> test this API without writing any code; however, it only appears to work
> with -cc1, not with -ObjC.
>
>
> On Wed, Apr 23, 2014 at 5:13 PM, Michael Bolin <bolinfest at gmail.com>wrote:
>
>> Here I have a very small .m file where I have typed "NSL" and would
>> expect the top code completion suggestion to be "NSLog()":
>>
>> https://gist.github.com/bolinfest/11236613
>>
>> Here is my C code that calls libclang and uses it to get suggested code
>> completions:
>>
>> https://gist.github.com/bolinfest/11236626
>>
>> Here are the suggestions I get when I run my C code (the command that I
>> ran is `./main.o Hello.m 5 6`):
>>
>> https://gist.github.com/bolinfest/11236652
>>
>> Some surprising results:
>>
>> (1) libclang gives me over 5000 suggestions.
>> (2) NSLog() is in the list, but its priority is 50. There are all sorts
>> of other suggestions that seem less relevant, but have a lower priority
>> (counterintuitively, this means higher probability of being clicked on:
>> http://clang.llvm.org/doxygen/group__CINDEX__CODE__COMPLET.html#ga46e843acdf63d9a7a0c7341a2d222c49).
>> Search for "priority=40" in the gist to see examples of results with a
>> lower priority that seem less relevant.
>> (3) The order in which things appear in the results appears to be random.
>> I see that clang has a convenience function to sort results alphabetically,
>> but not by priority.
>>
>> Are there additional arguments that I need to pass to libclang to tune
>> things so that the results I get from clang_codeCompleteAt() are more in
>> line with what I expect?
>>
>> Thank you,
>> Michael
>>
>>
>
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