* Add Wasmtime-specific C API functions to return errors
This commit adds new `wasmtime_*` symbols to the C API, many of which
mirror the existing counterparts in the `wasm.h` header. These APIs are
enhanced in a number of respects:
* Detailed error information is now available through a
`wasmtime_error_t`. Currently this only exposes one function which is
to extract a string version of the error.
* There is a distinction now between traps and errors during
instantiation and function calling. Traps only happen if wasm traps,
and errors can happen for things like runtime type errors when
interacting with the API.
* APIs have improved safety with respect to embedders where the lengths
of arrays are now taken as explicit parameters rather than assumed
from other parameters.
* Handle trap updates
* Update C examples
* Fix memory.c compile on MSVC
* Update test assertions
* Refactor C slightly
* Bare-bones .NET update
* Remove bogus nul handling
Add some crate features to compile out support for these features of the
C API. Avoiding these two features if they're not necessary shaves about
2MB off the final shared object in some local tests!
* Refactor and improve safety of C API
This commit is intended to be a relatively large refactoring of the C
API which is targeted at improving the safety of our C API definitions.
Not all of the APIs have been updated yet but this is intended to be the
start.
The goal here is to make as many functions safe as we can, expressing
inputs/outputs as native Rust types rather than raw pointers wherever
possible. For example instead of `*const wasm_foo_t` we'd take
`&wasm_foo_t`. Instead of returning `*mut wasm_foo_t` we'd return
`Box<wasm_foo_t>`. No ABI/API changes are intended from this commit,
it's supposed to only change how we define all these functions
internally.
This commit also additionally implements a few more API bindings for
exposed vector types by unifying everything into one macro.
Finally, this commit moves many internal caches in the C API to the
`OnceCell` type which provides a safe interface for one-time
initialization.
* Split apart monolithic C API `lib.rs`
This commit splits the monolithic `src/lib.rs` in the C API crate into
lots of smaller files. The goal here is to make this a bit more readable
and digestable. Each module now contains only API bindings for a
particular type, roughly organized around the grouping in the wasm.h
header file already.
A few more extensions were added, such as filling out `*_as_*`
conversions with both const and non-const versions. Additionally many
APIs were made safer in the same style as the previous commit, generally
preferring Rust types rather than raw pointer types.
Overall no functional change is intended here, it should be mostly just
code movement and minor refactorings!
* Make a few wasi C bindings safer
Use safe Rust types where we can and touch up a few APIs here and there.
* Implement `wasm_*type_as_externtype*` APIs
This commit restructures `wasm_externtype_t` to be similar to
`wasm_extern_t` so type conversion between the `*_extern_*` variants to
the concrete variants are all simple casts. (checked in the case of
general to concrete, of course).
* Consistently imlpement host info functions in the API
This commit adds a small macro crate which is then used to consistently
define the various host-info-related functions in the C API. The goal
here is to try to mirror what the `wasm.h` header provides to provide a
full implementation of the header.
