* Move back to only one WASI submodule
This commit fixes the issue where we have two WASI submodules for build
reasons in this repository. The fix was to place the submodule in the
`wasi-common` crate, and then anyone using the `wig` crate has to be
sure to define a `WASI_ROOT` env var in a build script to be able to
parse witx files.
With all that in place `wasi-common` becomes the source of truth for the
witx files we're parsing, and crates like `wasmtime-wasi` use
build-scripts shenanigans to read the same witx files. This should
hopefully get us so we're compatible with publishing and still only have
one submodule!
* rustfmt
* Auto-generate shims for old `wasi_unstable` module
This commit is effectively just doing what #707 already did, but
applying it to the `snapshot_0` module as well. The end result is the
same, where we cut down on all the boilerplate in `snapshot_0` and bring
it in line with the main `wasi_snapshot_preview1` implementation. The
goal here is to make it easier to change the two in tandem since they're
both doing the same thing.
* Migrate `wasi_common::hostcalls` to a macro
This commit migrates the `hostcalls` module to being auto-generated by a
macro rather than duplicating a handwritten signature for each wasi
syscall.
* Auto-generate snapshot_0's `hostcalls` module
Similar to the previous commit, but for `snapshot_0`
* Delete the `wasi-common-cbindgen` crate
This is no longer needed with the hostcalls macro now, we can easily
fold the definition of the cbindgen macro into the same crate.
* Rustfmt
* Fix windows build errors
* Rustfmt
* Remove now no-longer-necessary code
* rustfmt
This commit uses the `*.witx` files describing the current wasi API to
reduce the boilerplate used to define implementations in the
`wasmtime-wasi` crate. Eventually I'd like to remove lots of boilerplate
in the `wasi-common` crate too, but this should at least be a good start!
The boilerplate removed here is:
* No need to list each function to add it to the
`wasmtime_runtime::Module` being created
* No need to list the signature of the function in a separate
`syscalls.rs` file.
Instead the `*.witx` file is processed in a single-use macro inside the
`wasmtime-wasi` crate. This macro uses the signatures known from
`*.witx` to automatically register with the right type in the wasm
module as well as define a wrapper that the wasm module will call into.
Functionally this is all the same as before, it's just defined in a
different way now!
The shim generated by this macro which wasmtime calls into only uses
`i32`/`i64`/etc wasm types, and it internally uses `as` casts to convert
to the right wasi types when delegating into the `wasi-common` crate.
One change was necessary to get this implemented, however. The functions
in `wasi-common` sometimes took `WasiCtx` and sometimes took a slice of
memory. After this PR they uniformly all require both `WasiCtx` and
memory so the wrappers can be auto-generated. The arguments are ignored
if they weren't previously required.
