I tried a couple of different ways to squash this, and still don't think this is ideal, but I wanted to get it out for feedback.
Closes#5900Closes#9942
There are a few scenarios where the compiler tries to evaluate CastExprs without the corresponding types being available yet in the type context: https://github.com/mozilla/rust/issues/10618, https://github.com/mozilla/rust/issues/5900, https://github.com/mozilla/rust/issues/9942
This PR takes the approach of having eval_const_expr_partial's CastExpr arm fall back to a limited ast_ty_to_ty call that only checks for (a subset of) valid const types, when the direct type lookup fails. It's kind of hacky, so I understand if you don't want to take this as is. I'd need a little mentoring to get this into better shape, as figuring out the proper fix has been a little daunting. I'm also happy if someone else wants to pick this up and run with it.
This closes 5900 and 9942, but only moves the goalposts a little on 10618, which now falls over in a later phase of the compiler.
Previously, they were treated like ~[] and &[] (which can have length
0), but fixed length vectors are fixed length, i.e. we know at compile
time if it's possible to have length zero (which is only for [T, .. 0]).
Fixes#11659.
Previously, they were treated like ~[] and &[] (which can have length
0), but fixed length vectors are fixed length, i.e. we know at compile
time if it's possible to have length zero (which is only for [T, .. 0]).
Fixes#11659.
NodeIds are sequential integers starting at zero, so we can achieve some
memory savings by just storing the items all in a line in a vector.
The occupancy for typical crates seems to be 75-80%, so we're already
more efficient than a HashMap (maximum occupancy 75%), not even counting
the extra book-keeping that HashMap does.
Unsuffixed literals like 1 and 1.1, and free type parameters sometimes
have to be printed in error messages, which ended up with <V0>, <VI0>
and <VF0>. This change puts the words "generic" and "integer"/"float"
into the message so it's not a completely black box.
