Re: [PATCH V7 3/8] libgpiod: Add rust wrapper crate

[Kent Gibson <warthog618@gmail.com>]

On Fri, Oct 14, 2022 at 04:17:20PM +0530, Viresh Kumar wrote:
> Add rust wrapper crate, around the libpiod-sys crate added earlier, to
> provide a convenient interface for the users.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

One more thing - I overlooked trying to build on 32-bit while reviewing.
(in this case on a Raspberry Pi 4)

Unfortunately that fails:

   Compiling libgpiod v0.1.0 (/home/pi/libgpiod/bindings/rust/libgpiod)
error[E0308]: mismatched types
    --> libgpiod/src/edge_event.rs:32:88
     |
32   |         let event = unsafe { gpiod::gpiod_edge_event_buffer_get_event(buffer.buffer(), index) };
     |                              ----------------------------------------                  ^^^^^ expected `u32`, found `u64`
     |                              |
     |                              arguments to this function are incorrect
     |
note: function defined here
    --> /home/pi/libgpiod/bindings/rust/libgpiod-sys/src/bindings.rs:1151:12
     |
1151 |     pub fn gpiod_edge_event_buffer_get_event(
     |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
     |
32   |         let event = unsafe { gpiod::gpiod_edge_event_buffer_get_event(buffer.buffer(), index.try_into().unwrap()) };
     |                                                                                             ++++++++++++++++++++

error[E0308]: mismatched types
  --> libgpiod/src/edge_event.rs:81:18
   |
80 |     pub fn global_seqno(&self) -> u64 {
   |                                   --- expected `u64` because of return type
81 |         unsafe { gpiod::gpiod_edge_event_get_global_seqno(self.event) }
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
   |
help: you can convert a `u32` to a `u64`
   |
81 |         unsafe { gpiod::gpiod_edge_event_get_global_seqno(self.event).into() }
   |                                                                      +++++++

error[E0308]: mismatched types
  --> libgpiod/src/edge_event.rs:89:18
   |
88 |     pub fn line_seqno(&self) -> u64 {
   |                                 --- expected `u64` because of return type
89 |         unsafe { gpiod::gpiod_edge_event_get_line_seqno(self.event) }
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
   |
help: you can convert a `u32` to a `u64`
   |
89 |         unsafe { gpiod::gpiod_edge_event_get_line_seqno(self.event).into() }
   |                                                                    +++++++

error[E0308]: mismatched types
   --> libgpiod/src/line_config.rs:100:72
    |
100 |             unsafe { gpiod::gpiod_line_config_get_offsets(self.config, &mut num, &mut offsets) };
    |                      ------------------------------------              ^^^^^^^^ expected `u32`, found `u64`
    |                      |
    |                      arguments to this function are incorrect
    |
    = note:    expected raw pointer `*mut u32`
            found mutable reference `&mut u64`
note: function defined here
   --> /home/pi/libgpiod/bindings/rust/libgpiod-sys/src/bindings.rs:847:12
    |
847 |     pub fn gpiod_line_config_get_offsets(
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> libgpiod/src/line_info.rs:168:40
    |
168 |         Duration::from_micros(unsafe { gpiod::gpiod_line_info_get_debounce_period_us(self.info) })
    |                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
    |
help: you can convert a `u32` to a `u64`
    |
168 |         Duration::from_micros(unsafe { gpiod::gpiod_line_info_get_debounce_period_us(self.info).into() })
    |                                                                                                +++++++

error[E0308]: mismatched types
    --> libgpiod/src/line_request.rs:226:17
     |
223  |             gpiod::gpiod_line_request_read_edge_event(
     |             ----------------------------------------- arguments to this function are incorrect
...
226  |                 buffer.capacity() as u64,
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `u64`
     |
note: function defined here
    --> /home/pi/libgpiod/bindings/rust/libgpiod-sys/src/bindings.rs:1058:12
     |
1058 |     pub fn gpiod_line_request_read_edge_event(
     |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
     |
226  |                 (buffer.capacity() as u64).try_into().unwrap(),
     |                 +                        +++++++++++++++++++++

error[E0308]: mismatched types
   --> libgpiod/src/line_settings.rs:209:17
    |
207 |             gpiod::gpiod_line_settings_set_debounce_period_us(
    |             ------------------------------------------------- arguments to this function are incorrect
208 |                 self.settings,
209 |                 period.as_micros() as u64,
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `u64`
    |
note: function defined here
   --> /home/pi/libgpiod/bindings/rust/libgpiod-sys/src/bindings.rs:746:12
    |
746 |     pub fn gpiod_line_settings_set_debounce_period_us(
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
    |
209 |                 (period.as_micros() as u64).try_into().unwrap(),
    |                 +                         +++++++++++++++++++++

error[E0308]: mismatched types
   --> libgpiod/src/line_settings.rs:217:13
    |
217 |             gpiod::gpiod_line_settings_get_debounce_period_us(self.settings)
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
    |
help: you can convert a `u32` to a `u64`
    |
217 |             gpiod::gpiod_line_settings_get_debounce_period_us(self.settings).into()
    |                                                                             +++++++

For more information about this error, try `rustc --explain E0308`.
error: could not compile `libgpiod` due to 8 previous errors

---

An example of one of the relevant generated signatures is:

    pub fn gpiod_edge_event_buffer_get_event(
        buffer: *mut gpiod_edge_event_buffer,
        index: ::std::os::raw::c_ulong,
    ) -> *mut gpiod_edge_event;

On 32-bit c_ulong maps to u32, not u64.

Cheers,
Kent.