[Lldb-commits] [PATCH] D24591: [LIT] First pass of LLDB LIT support

Jason Molenda via lldb-commits lldb-commits at lists.llvm.org
Thu Sep 15 19:28:26 PDT 2016

> On Sep 15, 2016, at 8:02 AM, Zachary Turner <zturner at google.com> wrote:
> It sounds like your goal is also "tests have to use the SB API and no other API", which if so I think that's counterproductive.   More productive, IMO, would be being open to any alternative that addresses the concerns you have with command-line tests.  There are more than 2 ways to skin a cat, so to speak.

Thinking about this a bit, another approach would be to do lit tests on top of lldb-mi.  MI is a structured format for the debugger and a UI to communicate back and forth with a simple text markup language (it would be JSON if it were being done today, but it was added to gdb eighteen years ago, so it's not).  The commands correspond to the commands a debugger user would think to use -- no need to understand the structure of how lldb is implemented, like with the SB API.  The format is a little unusual for a human to type, but back when we supported gdb at Apple we worked in MI all the time (it was used to communicate between Xcode, our IDE, and gdb) by hand when testing and it was fine. "-exec-run" instead of run, that kind of thing.  I think there are four dozens different commands.

lldb-mi itself uses SB API.  And the concerns about hardcoding command line UI don't apply, it's a key-value format intended for computers, no one is going to add an extra space character to anything -- the most it changes is that new key-value pairs are added to responses.

I agree there are many acceptable ways to write lit tests that don't involve lldb command line scraping, and I'm all in favor of using lit with tests that don't do that.  Of course the patch we're discussing has lit test examples that contradict our own policy on writing tests.  Once lit is supported in lldb, are we going to reject any testsuite additions that depend on the text output from the command line lldb?  If we're all on the same page here, then I have no reservations.

Just to say out loud the future I can easily see:  We add lit, then we have people helpfully write a few dozen tests in lit that depend on the command line debugger output.  Those patches have to be rejected.  


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