staticIndexOf is incredibly slow and memory intensive

[Andrej Mitrovic]

Maybe this is CTFE to blame more than the function itself.

I have a project where I have a TypeTuple that holds a class tree of a
wrapped C++ library. The tuple is iterated from in several places
where an index has to be retrieved. Compiling this project takes 46
seconds when using staticIndexOf and uses 700 MB RAM. If I replace it
with my own hardcoded function below it takes only 5 seconds and uses
150 MB RAM. This is what the function looks like:

template myStaticIndexOf(T, TList...)
{
    static if (is(typeof(T == TList[0])) && is(T == TList[0]))
        enum myStaticIndexOf = 0;
    else
    static if (is(typeof(T == TList[1])) && is(T == TList[1]))
        enum myStaticIndexOf = 1;
    else
    // ... and so on ...
}

The body is pregenerated of course, using mixin() would slow down
compilation here as well.

When wrapping larger libraries (and hence having a larger TypeTuple)
and using staticIndexOf the memory usage becomes so high that the
compiler runs out of memory and crashes.

I really think it sucks that I have to resort to manually
pre-generating a function body externally as if I were using a lame
(CTFE-wise) language like C++03.

D *has* to be better than this..