[phobos] Building generated/osx/release/32/unittest/std/string takes 400+ seconds on OSX

[Jonathan M Davis]

On Saturday, September 24, 2011 18:55:19 Andrei Alexandrescu wrote:
> On 9/24/11 4:25 PM, Jonathan M Davis wrote:
> > My guess would be that it has to do with the foreach loops over
> > TypeTuples that std.string uses to generate a number of its tests, but
> > I don't know.
> The test of tr is the culprit (shown at the bottom of this). It does a
> triple nested loop over string types.
> 
> Jonathan, did you time using the latest compiler? Walter, did you enable
> the GC for OSX too?

I was probably a few commits off of the latest, but I just updated and tried 
again, and the results are pretty much the same. From the dmd-internals 
discussion on the GC stuff though, I got the impression that they only enabled 
it on Windows. I don't know though.

> Should we disable this test, reduce it, or have Walter look into
> improving the compiler?

I am of the opinion that the test should work and compile reasonably quickly. 
I have found tests like this to be very useful in finding problems relating to 
template constraints, constness, and encodings - particularly when dealing 
with the various string and character types. Granted, three levels of nesting 
of static foreach loops is a bit much (I think that the most that I normally 
end up with is two), but in this case, it was necessary to cover all of the 
combinations of types.

Now, it may be that we're going to need to disable this test temporarily on 
some set of platforms in order to reduce the time it takes to run the tests, 
but I am definitely of the opinion that the compiler should be fixed rather than 
us writing the tests off as infeasible. We can also reduce the number of test 
cases, but then it becomes much easier for bugs to get through which only 
affect a particular combination of character types and don't get caught.

And if this problem is due to the enabling of the GC at compile time, then it 
seems to me that this is a good test case in that it's catching a problem with 
the GC that needs to be fixed.

- Jonathan M Davis