rust elektra fails to build

[markus2330]

cd src/bindings/rust/elektra
git mv published_Cargo.toml Cargo.toml 
cargo build # or cargo publish

   Compiling elektra v0.11.0 (/home/markus/Projekte/Elektra/libelektra/src/bindings/rust/elektra)
error[E0308]: mismatched types
   --> elektra/src/key.rs:221:21
    |
218 |                 elektra_sys::keySetBinary(
    |                 ------------------------- arguments to this function are incorrect
...
221 |                     data.len(),
    |                     ^^^^^^^^^^ expected `u64`, found `usize`
    |
note: function defined here
   --> /home/markus/Projekte/Elektra/libelektra/src/bindings/rust/target/debug/build/elektra-sys-122c63e9e91011d8/out/bindings.rs:242:12
    |
242 |     pub fn keySetBinary(
    |            ^^^^^^^^^^^^
help: you can convert a `usize` to a `u64` and panic if the converted value doesn't fit
    |
221 |                     data.len().try_into().unwrap(),
    |                               ++++++++++++++++++++

error[E0308]: mismatched types
   --> elektra/src/key.rs:235:17
    |
232 |             elektra_sys::keyGetBinary(
    |             ------------------------- arguments to this function are incorrect
...
235 |                 vec.capacity(),
    |                 ^^^^^^^^^^^^^^ expected `u64`, found `usize`
    |
note: function defined here
   --> /home/markus/Projekte/Elektra/libelektra/src/bindings/rust/target/debug/build/elektra-sys-122c63e9e91011d8/out/bindings.rs:235:12
    |
235 |     pub fn keyGetBinary(
    |            ^^^^^^^^^^^^
help: you can convert a `usize` to a `u64` and panic if the converted value doesn't fit
    |
235 |                 vec.capacity().try_into().unwrap(),
    |                               ++++++++++++++++++++

error[E0308]: mismatched types
  --> elektra/src/readable.rs:43:18
   |
42 |     fn basename_size(&self) -> isize {
   |                                ----- expected `isize` because of return type
43 |         unsafe { elektra_sys::keyGetBaseNameSize(self.as_ref()) }
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `isize`, found `i64`
   |
help: you can convert an `i64` to an `isize` and panic if the converted value doesn't fit
   |
43 |         unsafe { elektra_sys::keyGetBaseNameSize(self.as_ref()).try_into().unwrap() }
   |                                                                ++++++++++++++++++++

error[E0308]: mismatched types
   --> elektra/src/keyset.rs:177:50
    |
177 |         let ks_ptr = unsafe { elektra_sys::ksNew(capacity, elektra_sys::KS_END) };
    |                               ------------------ ^^^^^^^^ expected `u64`, found `usize`
    |                               |
    |                               arguments to this function are incorrect
    |
note: function defined here
   --> /home/markus/Projekte/Elektra/libelektra/src/bindings/rust/target/debug/build/elektra-sys-122c63e9e91011d8/out/bindings.rs:257:12
    |
257 |     pub fn ksNew(alloc: size_t, ...) -> *mut KeySet;
    |            ^^^^^
help: you can convert a `usize` to a `u64` and panic if the converted value doesn't fit
    |
177 |         let ks_ptr = unsafe { elektra_sys::ksNew(capacity.try_into().unwrap(), elektra_sys::KS_END) };
    |                                                          ++++++++++++++++++++

error[E0308]: mismatched types
   --> elektra/src/keyset.rs:194:18
    |
193 |     pub fn append(&mut self, to_append: &KeySet) -> isize {
    |                                                     ----- expected `isize` because of return type
194 |         unsafe { elektra_sys::ksAppend(self.as_ptr(), to_append.as_ref()) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `isize`, found `i64`
    |
help: you can convert an `i64` to an `isize` and panic if the converted value doesn't fit
    |
194 |         unsafe { elektra_sys::ksAppend(self.as_ptr(), to_append.as_ref()).try_into().unwrap() }
    |                                                                          ++++++++++++++++++++

For more information about this error, try `rustc --explain E0308`.
error: could not compile `elektra` due to 5 previous errors

[markus2330]

Note: elektra-sys 0.11.0 is already published

[horenso]

The first error seems to be that:

extern "C" {
    pub fn keySetBinary(
        key: *mut Key,
        newBinary: *const ::std::os::raw::c_void,
        dataSize: size_t,
    ) -> ssize_t;
}

dataSize uses size_t, which is the size of a pointer (32bit/64bit usually). Now in our call:

unsafe {
    elektra_sys::keySetBinary(
        self.as_ptr(),
        data.as_ptr() as *const std::os::raw::c_void,
        data.len(),
    );
}

data.len() returns a usize which is supposed to be the same concept, a pointer sized unsized integer.

ChatGPT semi-helpfully says: "The complaint you're getting suggests that the Rust type usize doesn't match the expected C type size_t.". I'm going to research why the types no longer match.

[markus2330]

@horenso Thx for the triage. Looking forward to a PR.