Hi,

This week, I concluded that the best approach for _d_arrayctor, based on the performance calculated in this post is to change its purity from strong to weak by adding a third, unused, pointer-type parameter. This new signature was implemented in this PR and the PR for lowering to _d_arrayctor is waiting to be merged. So it seems the _d_arrayctor saga is over for now.

Other than this, I started working on _d_delstruct, which I converted to a template in druntime here. I was also able to update its lowering in the compiler. The only inconvenience now is that the call to _d_delstruct is also subject to semantic analysis, as opposed to the old hook, which was introduced in a later phase, by e2ir.d. Because the new hook is analysed semantically, some compiler tests in fail_compilation/ also output @safe-ty, purity and nogc errors related to _d_delstruct, and not just those coming from the dtor that's being called by delete. I am currently working on a way to filter out the errors that mention _d_delstruct, as lowerings should be transparent to programmers.

Also this week I spent some time fixing the multiple calls to _d_arrayappendcTX that were created by the compiler for tests such as (a ~= 1) ~= 2. The reason is that the lowering of a ~= x is actually this:

__ctfe ? a ~= x : _d_arrayappendcTX(a, 1), a[$ - 1] = x, a;

Because a is used literally, as an expression, in case it's something more complex, such as, in this case, a ~= 1, the concatenation is made each time a appears in the second term of the conditional statement. I am now trying to solve the error by saving the result of a in a temporary variable, in case it's not a regular array.

Thanks,
Teodor