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

[Manuel Klimek via cfe-dev]

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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