I believe this patch incorporates all expected syntax changes from extern
function reform (#3678). You can now write things like:
extern "<abi>" fn foo(s: S) -> T { ... }
extern "<abi>" mod { ... }
extern "<abi>" fn(S) -> T
The ABI for foreign functions is taken from this syntax (rather than from an
annotation). We support the full ABI specification I described on the mailing
list. The correct ABI is chosen based on the target architecture.
Calls by pointer to C functions are not yet supported, and the Rust type of
crust fns is still *u8.
Various FIXME comments added around to denote copies which when removed cause
the compiler to segfault at some point before stage2. None of these copies
should even be necessary.
and from typeck, which is verboten. We are supposed to write inference results
into the FnCtxt and then these get copied over in writeback. Add assertions
that no inference by-products are added to this table.
Fixes#3888Fixes#4036Fixes#4492
Later changes on this branch adapt the rest of rustc::middle::trans
to use this module instead of scattered hard-coded knowledge of
representations; a few of them also have improvements or cleanup for
adt.rs (and many added comments) that weren't drastic enough to justify
changing history to move them into this commit.
The basic idea is that we add a new kind of adjustment, AutoAddEnv, that pads
an extern fn into a closure by adding the extra NULL word. Then there are a few
misc changes in trans to get the LLVM types to match up.
Fixes#4808.
Note on `struct_elt`: the comment is wrong, it actually dereferences the nth element of LLVM struct type if it is a pointer. That's why `T_ptr` is removed in `callee.rs`.
`simplify_type` was bogus, as there was no way for it to handle enums
properly. It was also slow, because it created many Rust types at runtime. In
general creating Rust types during trans is a source of slowness, and I'd like
to avoid doing it as much as possible. (It is probably not possible to
eliminate it entirely, due to `subst`, but we should get rid of as much of it
as we can.) So this patch replaces `simplify_type` with `sizing_type_of`,
which creates a size-equivalent LLVM type directly without going through a
Rust type first.
Because this is causing an ICE in Servo, I'm rubber stamping it.
