[cfe-dev] [PATCH] Fixit for incorrect includes

[David Blaikie]

On Tue, Jul 17, 2012 at 11:35 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
> On Tue, Jul 17, 2012 at 1:10 PM, David Blaikie <dblaikie at gmail.com> wrote:
>> On Tue, Jul 17, 2012 at 11:01 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
>>> On Tue, Jul 17, 2012 at 12:55 PM, David Blaikie <dblaikie at gmail.com> wrote:
>>>> On Tue, Jul 17, 2012 at 10:48 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
>>>>> On Tue, Jul 17, 2012 at 12:10 PM, David Blaikie <dblaikie at gmail.com> wrote:
>>>>>> On Tue, Jul 17, 2012 at 9:14 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
>>>>>>> This patch creates a fixit for include directives where the file could
>>>>>>> not be found when using angle brackets, but can be found when using
>>>>>>> quotes.  The converse is not needed since quoted includes will search
>>>>>>> angle bracket locations by default.
>>>>>>>
>>>>>>> Eg)
>>>>>>> #include <header.h>  // can be found via #include "header.h" instead
>>>>>>>
>>>>>>> Thoughts?
>>>>>>
>>>>>> Seems like a neat idea to me - but I'm not an authoritative sign-off.
>>>>>>
>>>>>> You used NULL as null constants for 2 of the conditional operators,
>>>>>> then 0 for the third - that seems inconsistent. You might want to
>>>>>> check what the prevailing style is in this file & stick to that
>>>>>> (generally in LLVM, '0' seems to be winning as the authoritative null
>>>>>> pointer constant, I believe).
>>>>>
>>>>> Easy enough to rectify (I'll standardize on 0) -- this was a copy from
>>>>> above, so I'll fix up there as well.
>>>>>
>>>>>> Did you consider adding this case to the existing fixit testing files?
>>>>>> They're already a grab-bag of things that can be fixed (this helps
>>>>>> keep the test suite fast by not adding more separate test file
>>>>>> executions) & this seems like it'd be at home there.
>>>>>
>>>>> I thought about it, but it strikes me as different enough to warrant
>>>>> its own test case.  Specifically, the fixit behavior is kind of
>>>>> tricky.  Because the fixit writes out a separate file, but in a
>>>>> different directory, I have to be a bit sneaky otherwise the header
>>>>> file isn't available.  This is because the temp file goes to the
>>>>> Output directory, but the header file remains in the FixIt directory.
>>>>> To work around this, I copy the testcase to a temp file, modify the
>>>>> testcase file directly with the fixit,
>>>>
>>>> Why can't you modify the temp file directly instead? (& you'd have to
>>>> copy the header over too, I suppose - you can identify the temp
>>>> directory with %T which means you can copy to fixed name files if
>>>> that's important (as it would be for the header name): %T/foo.cpp or
>>>> whatever)
>>>
>>> You learn something new every day!  I didn't realize you could use %T
>>> for the temp directory.  Now the testcase looks like:
>>>
>>> // RUN: %clang_cc1 -fsyntax-only -verify %s
>>> // RUN: cp %s %t
>>> // RUN: cp %S/fixit-include.h %T
>>> // RUN: not %clang_cc1 -fsyntax-only -fixit %t
>>> // RUN: %clang_cc1 -Wall -pedantic %t
>>>
>>> Which is cleaner (to me).  Thanks!
>>>
>>>> & yeah, arguable whether the existing fixit cases should be burdened
>>>> with this mucking about - I don't mind too strongly either way.
>>>
>>> Since include errors are fatal,
>>
>> This actually raises a good question/point: when Clang encounters
>> fatal errors it basically stops, right? (it doesn't produce more
>> diagnostics) That's incorrect if we've provided a fixit and recovered
>> from the error - when fixits are provided we should recover as if the
>> code were written that way. With your change as it stands we
>> "successfully" apply fixits for this code:
>>
>> #include <non_existent.h>
>> int main(float) {
>> }
>>
>> because we didn't provide the error about main. What we should get is
>> the error about main and no fixit application because we encountered
>> an unfixable error.
>
> I'm not actually recovering with my patch -- I'm still early returning
> out of HandleIncludeDirective.

Yep, that's probably incorrect. If Clang issues a fixit, it
should/must recover as if the user wrote the code the way the fixit
suggests.

> So if this is possible to "fixit",
> does that mean this really shouldn't be a fatal error in this case?

I believe so, yes.

- David