[Lldb-commits] [PATCH] D54009: Refactor LLDB lit configuration files

[Zachary Turner via lldb-commits]

Ok so for dotest, it seems to be ignoring the config.cc and config.cxx
entirely.  So we can theoretically do whatever we want with it, or change
around the directory structure so that it's more like:

lldb
* lit
* * Dotest
* * Unit
* * Tests

and put the config.cc / config.cxx logic under Tests.  That's a large
change though and probably not worth making such a large change right away.

dotest tests manually construct the command line directly in CMake via this
`LLDB_DOTEST_ARGS_PROPERTY` global property, and then in
lldb/lit/Suite/lit.cfg we have this line:

dotest_cmd = [config.dotest_path, '-q']
dotest_cmd.extend(config.dotest_args_str.split(';'))


So pretty much everythign the parent lit file has done is totally ignored.

With that in mind, **for the lit tests only** I propose dropping support
for non-clang compilers and ignoring LLDB_TEST_C_COMPILER and
LLDB_TEST_CXX_COMPILER (you can still have a custom path to clang
executable via an environment variable, which is consistent with how
clang's test suite works).

Note that when you run ninja check-lldb-lit you will now get messages that
tell you the exact path to the clang executable, so you can see what the
PATH resolution is doing.

On Tue, Nov 13, 2018 at 4:02 PM Zachary Turner <zturner at google.com> wrote:

> On Tue, Nov 13, 2018 at 3:47 PM Stella Stamenova <stilis at microsoft.com>
> wrote:
>
>> I am not sure if that’s the right solution for a couple of reasons:
>>
>>    1. As far as I can tell only clang calls use_clang (and only lld
>>    calls use_lld), while the other projects such as lld and llvm rely on the
>>    environment to be setup correctly
>>    2. Lld also has tests that invoke clang-cl and they pass – while the
>>    ones in LLDB do not, so the invocation of use_clang is not necessary for
>>    the tests to pass (maybe?)
>>    3. LLDB allows us to specify whether to use gcc or clang as well as
>>    the path and it can also have a test compiler specified via
>>    LLDB_USE_TEST_*_COMPILER, so we should first decide what scenarios we want
>>    to support before trying to make this work and possibly making it even more
>>    confusing and complicated
>>
>>
>>
>> Do you know what the answer for 3) is? What compilers are valid to
>> specify for the lit/suite/unittests via the various parameters?
>>
>
> For the unit tests, I don't think we ever specify a compiler, or we don't
> ever read the value.  Because a unit test shouldn't be compiling anything,
> it's a different kind of test.
>
> For the dotest suite, specifying the compiler is important and it can
> definitely be gcc, but I don't think this uses the same method of going
> through config.cc.  In fact, I'm not sure how it determines what compiler
> to use at the moment, as it's been a number of years since I've looked at
> the dotest suite.
>
> For the lit tests, I'm inclined to say we should keep things simple and
> only support clang for now, and add support for new compilers such as gcc
> if and when someone actually wants it.  Otherwise YAGNI.
>
> Definitely that time will come, but it doesn't make sense to support it
> immediately if nobody is using it today and nobody is planning to enable it
> immediately.
>
> So I'm tempted to say that perhaps we should just call
> llvm_config.use_clang() and llvm_config.use_lld() and ignore
> LLDB_TEST_COMPILER, which in my experience has only been a source of
> unnecessary complexity that never actually gets used in practice.
>
>>
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