[lldb-dev] Questions about the LLDB testsuite and improving its reliability

[Adrian Prantl via lldb-dev]

> On Jan 18, 2018, at 5:07 AM, Pavel Labath <labath at google.com> wrote:
> 
> Looks like I missed a party. :)
> 
> I'll try to give my thoughts on some of the things that were said here:
> 
>> make -C
> I don't think make -C does what you think it does. "make -C foo" is
> basically equivalent to "cd foo && make", which is what we are doing
> now already. Of course, you can make this work, but you would have to
> pass an extra OUTDIR=... argument to make and then modify the
> Makefiles to reference $(OUTDIR) for its outputs:
> $(OUTDIR)/a.out: main.cc
>  $(CC) -o $(OUTDIR)/a.out main.cc ...
> 
> The standard way of doing an out-of-tree build with make is to have
> the Makefile in the build-directory and to set the magic VPATH
> variable in the Makefile (or as a part of make invocation). VPATH
> alters make's search path, so when searching for a dependency foo and
> the foo is not present in the current (build) directory, it will go
> searching for it in the VPATH (source) directory. You still need to be
> careful about paths in the command line (generally this means using
> make variables like $@ and $< instead of bare file names), but our
> makefiles are generally pretty good at this already. We even have a
> couple of makefiles using VPATH already (see TestConcurrentEvents) --
> Todd added this to speed up the build by spreading out tests over
> different folders while sharing sources (the serial execution
> problem).
> 
> I still fully support being able to build the tests out of tree, I
> just think it may be a bit more involved than you realise.

I uploaded my first attempt of implementing something along these lines to https://reviews.llvm.org/D42281 . Feedback of all kinds is very welcome!

-- adrian