Clang can emulate GNUC or MSVC behaviors. So instead of detecting
whether Clang is used to compile the code, it's better to detect the
targeted features are available.
Code proposed by @nlewycky, thanks!
This PR defines a cross-compiler `DEPRECATED(message)` macro. It must
be used as follows in Rust:
```rust
/// This is a documentation.
/// cbindgen:prefix=DEPRECATED(This is a deprecation message.")
pub extern "C" fn wasmer_foo() -> c_uint {
42
}
```
It will generate the following C header:
```c
/**
* This is a documentation.
*/
DEPRECATED("This is a deprecation message.")
unsigned int wasmer_foo();
```
And once this code is used by a C compiler, it will print something
like this (example from Clang):
```
…/test.c:…:…: error: 'wasmer_foo' is deprecated: This is a deprecation message. [-Werror,-Wdeprecated-declarations]
unsigned int x = wasmer_foo();
^
…/wasmer.h:…:…: note: 'wasmer_foo' has been explicitly marked deprecated here
DEPRECATED("This is a deprecation message.")
^
…/wasmer.h:…:…: note: expanded from macro 'DEPRECATED'
```
This is required for further deprecations.
When the version has type `Version`, we expect the user to give a
valid `Version` variant. Since the `Version` is basically a `uint8_t`,
the user is able to pass everything she wants, which can create an
undefined behavior on the Rust side.
To avoid such situation, the version has now type `c_uchar` (`unsigned
char` or `uint8_t` on C side —on most platforms). Then the `From`
trait is implemented on `Version`. In case the value is unbound,
`Version::Unknown` is returned.
This patch updates `test-wasi-import-object` to test the new
`wasmer_wasi_get_version` &
`wasmer_wasi_generate_import_object_for_version` functions, and the
new `Version` type.
This patch introduces 2 new functions:
* `wasmer_wasi_generate_import_object_for_version` and
* `wasmer_wasi_get_version`.
It mimics the current API provided by `wasmer_wasi`, nothing fancy
here. It's just a regular port to C/C++.
Because `wasmer_wasi::get_wasi_version` returns an option, and in
order to simplify the C/C++ API, `wasmer_wasi_get_version` can return
`Version::Unknown` in case of an error. It's up to the user to check
the version is valid (i.e. not unknown).
