[cfe-dev] LibTooling in the absence of a compilation database

Manuel Klimek via cfe-dev cfe-dev at lists.llvm.org
Wed Dec 2 08:09:57 PST 2015


On Wed, Dec 2, 2015 at 5:07 PM Russell Wallace <russell.wallace at gmail.com>
wrote:

> Okay, I'm looking through the code to see if I can put together a patch.
> In this project, is it considered preferable to minimize the number of
> lines changed in the patch, or minimize the size of the code after the
> patch?
>

How about "maximize the quality of the code after the patch" :D


>
> On Wed, Dec 2, 2015 at 9:55 AM, Manuel Klimek <klimek at google.com> wrote:
>
>> On Wed, Dec 2, 2015 at 10:47 AM Russell Wallace <
>> russell.wallace at gmail.com> wrote:
>>
>>> Then, if the database is not found, the tool can print a note like
>>> 'compilation database not found, using default options'.
>>>
>>
>> Ok, with that diagnostic I'd approve a change to that end.
>>
>>
>>>
>>> On Wed, Dec 2, 2015 at 9:45 AM, Manuel Klimek <klimek at google.com> wrote:
>>>
>>>> On Wed, Dec 2, 2015 at 10:43 AM Russell Wallace <
>>>> russell.wallace at gmail.com> wrote:
>>>>
>>>>> There are none that are guaranteed to work in all cases; nonetheless,
>>>>> if Clang, GCC or Microsoft C++ is presented with a 'hello world' test
>>>>> program with no other options, it will successfully compile it with its
>>>>> built-in defaults, so the defaults for a tool should be those that Clang
>>>>> would use in the same circumstances. (I do have some ideas for automated
>>>>> search for the correct options if the defaults fail, but in the meantime
>>>>> 'do what the actual compiler would do' would be a good baseline.)
>>>>>
>>>>
>>>> The problem is that if this happens, it's hard to tell the user what
>>>> they need to do to get the tool to work (set up a compilation database).
>>>> How about we add to the error if there is not compilation database how
>>>> to run it in default mode (by adding -- at the end)?
>>>>
>>>>
>>>>>
>>>>> On Wed, Dec 2, 2015 at 9:39 AM, Manuel Klimek <klimek at google.com>
>>>>> wrote:
>>>>>
>>>>>> On Wed, Dec 2, 2015 at 10:35 AM Russell Wallace via cfe-dev <
>>>>>> cfe-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>>> Tools built with LibTooling default to using a compilation database
>>>>>>> if one is available, which is good.
>>>>>>>
>>>>>>> In the case where a compilation database is not available, there is
>>>>>>> a problem: the default behavior is to exit with an error message, whereas
>>>>>>> in some cases the tool would be required to do the best it can anyway. This
>>>>>>> can be achieved by adding -- to the end of the command line, but this
>>>>>>> wouldn't be obvious to someone unfamiliar with Clang tools.
>>>>>>>
>>>>>>> One solution would be for the program to append -- to argv if it's
>>>>>>> not already present, but would this disable the default useful behavior of
>>>>>>> reading the compilation database if it is available?
>>>>>>>
>>>>>>> If so, is there a way for the program to say 'okay, check for a
>>>>>>> compilation database as normal, but if it's not present, let me know and
>>>>>>> I'll fill in some best-guess default options'?
>>>>>>>
>>>>>>
>>>>>> The problem is that for C++ there really are no best guess default
>>>>>> options. If you have ideas for what they should be, please make a proposal.
>>>>>>
>>>>>>
>>>>>>> _______________________________________________
>>>>>>> cfe-dev mailing list
>>>>>>> cfe-dev at lists.llvm.org
>>>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>>>>
>>>>>>
>>>>>
>>>
>
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