Build Error on armv7l (RasperryPI): glib::translate::ToGlibPtr<'_, *mut i8> is not implemented for std::path::Path

[meldron]

Hi there,

I am trying to build https://github.com/centricular/gstwebrtc-demos/tree/master/sendrecv/gst-rust on a raspberry pi armv7l and just ran in the following error which i did not get on x86_64.

cargo build

Compiling gio v0.4.0 (https://github.com/gtk-rs/gio#b95e3d5d)
error[E0277]: the trait bound `std::path::Path: glib::translate::ToGlibPtr<'_, *mut i8>` is not satisfied
  --> /home/pi/.cargo/git/checkouts/gio-a4b825b310a073b9/b95e3d5/src/unix_socket_address.rs:56:37
   |
56 |                 Path(path) => (path.to_glib_none().0, path.as_os_str().len()),
   |                                     ^^^^^^^^^^^^ the trait `glib::translate::ToGlibPtr<'_, *mut i8>` is not implemented for 
`std::path::Path`
   |
   = help: the following implementations were found:
             <std::path::Path as glib::translate::ToGlibPtr<'a, *const u8>>
             <std::path::Path as glib::translate::ToGlibPtr<'a, *mut u8>>

error[E0308]: mismatched types
  --> /home/pi/.cargo/git/checkouts/gio-a4b825b310a073b9/b95e3d5/src/unix_socket_address.rs:61:84
   |
61 |             SocketAddress::from_glib_full(ffi::g_unix_socket_address_new_with_type(path, len as i32, type_.to_glib()))
   |                                                                                    ^^^^ expected u8, found i8
   |
   = note: expected type `*mut u8`
              found type `*mut i8`

error: aborting due to 2 previous errors

Some errors occurred: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.
error: Could not compile `gio`.

To learn more, run the command again with --verbose.

I built the gio library with gstreamers cerbero installation (both on armv7l and x86_64) and pkg-config --modversion gio-2.0 returns version 2.56.1 on both machines.

[meldron]

I just tried to build gstreamer-rtsp-server by itself and i got even more errors:

error[E0308]: mismatched types
  --> /home/pi/.cargo/git/checkouts/gio-a4b825b310a073b9/98d1501/src/desktop_app_info.rs:23:41
   |
23 |                 let tmp: *mut *mut i8 = *out.offset(it);
   |                                         ^^^^^^^^^^^^^^^ expected i8, found u8
   |
   = note: expected type `*mut *mut i8`
              found type `*mut *mut u8`
error[E0277]: the trait bound `std::string::String: glib::translate::FromGlibPtrArrayContainerAsVec<_, *mut *mut i8>` is not satisfied
  --> /home/pi/.cargo/git/checkouts/gio-a4b825b310a073b9/98d1501/src/desktop_app_info.rs:28:38
   |
28 |                 let v: Vec<String> = FromGlibPtrContainer::from_glib_full(tmp);
   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `glib::translate::FromGlibPtrArrayContainerAsVec<_, *mut *mut i8>` is not implemented for `std::string::String`
   |
   = help: the following implementations were found:
             <std::string::String as glib::translate::FromGlibPtrArrayContainerAsVec<*const u8, *mut *const u8>>
             <std::string::String as glib::translate::FromGlibPtrArrayContainerAsVec<*const u8, *const *const u8>>
             <std::string::String as glib::translate::FromGlibPtrArrayContainerAsVec<*mut u8, *mut *mut u8>>
             <std::string::String as glib::translate::FromGlibPtrArrayContainerAsVec<*mut u8, *const *mut u8>>
   = note: required because of the requirements on the impl of `glib::translate::FromGlibPtrContainer<_, *mut *mut i8>` for `std::vec::Vec<std::string::String>`
   = note: required by `glib::translate::FromGlibPtrContainer::from_glib_full`
error[E0277]: the trait bound `std::path::Path: glib::translate::ToGlibPtr<'_, *mut i8>` is not satisfied
  --> /home/pi/.cargo/git/checkouts/gio-a4b825b310a073b9/98d1501/src/unix_socket_address.rs:56:37
   |
56 |                 Path(path) => (path.to_glib_none().0, path.as_os_str().len()),
   |                                     ^^^^^^^^^^^^ the trait `glib::translate::ToGlibPtr<'_, *mut i8>` is not implemented for `std::path::Path`
   |
   = help: the following implementations were found:
             <std::path::Path as glib::translate::ToGlibPtr<'a, *const u8>>
             <std::path::Path as glib::translate::ToGlibPtr<'a, *mut u8>>
error[E0308]: mismatched types
  --> /home/pi/.cargo/git/checkouts/gio-a4b825b310a073b9/98d1501/src/unix_socket_address.rs:61:84
   |
61 |             SocketAddress::from_glib_full(ffi::g_unix_socket_address_new_with_type(path, len as i32, type_.to_glib()))
   |                                                                                    ^^^^ expected u8, found i8
   |
   = note: expected type `*mut u8`
              found type `*mut i8`
error[E0308]: mismatched types
   --> gstreamer/src/tags.rs:197:39   
    |
197 |                 ffi::gst_tag_get_type(tag_name.as_ptr() as *const i8)
    |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected u8, found i8
    |
    = note: expected type `*const u8` 
               found type `*const i8` 

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
error: Could not compile `gstreamer`. 
warning: build failed, waiting for other jobs to finish...
error: aborting due to 4 previous errors

Some errors occurred: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.
error: Could not compile `gio`.

[sdroege]

Ok, mismatch between signed and unsigned everywhere. See
https://github.com/rust-lang/libc/blob/master/src/unix/notbsd/linux/musl/b32/arm.rs#L1
vs
https://github.com/rust-lang/libc/blob/master/src/unix/notbsd/linux/musl/b64/x86_64.rs#L1
for example.

We need to consistently use c_char I guess

[sdroege]

Hmm but we do: https://github.com/gtk-rs/glib/blob/master/src/translate.rs#L474

Can you check in your Cargo.lock is there are multiple versions of the libc crate linked in?

[meldron]

In the lock file of gstreamer-rs all libc versions are 0.2.42 and in gst-rust's lock file all versions are 0.2.41.

[sdroege]

Those definitions also didn't change for years. Ok, someone will have to reproduce and follow the types. Somewhere there must be a u8 or i8 instead of c_char

error[E0308]: mismatched types
   --> gstreamer/src/tags.rs:197:39   
    |
197 |                 ffi::gst_tag_get_type(tag_name.as_ptr() as *const i8)
    |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected u8, found i8
    |
    = note: expected type `*const u8` 
               found type `*const i8` 

This is a bug in gstreamer-rs btw, there might be more like this there. I'll check next week unless you want to send me a PR. @meldron

[meldron]

@sdroege thanks for your input, I opened an issue at sdroege/gstreamer-rs/, and i will try to look into it, but i am not sure where to look.

[sdroege]

For gstreamer it's exactly in line 197 there. See my comment in the other ticket :)

For GLib/GIO I don't know either, you'll have to look at each of the errors individually, look at the types of function arguments/return values, local variables, etc and see where exactly the i8 or u8 comes from that should actually be a c_char. Or cast accordingly if needed.

[meldron]

I will look for more and submit a PR if I am successful.

[sdroege]

The GStreamer part is fixed now, I'm looking at the GTK part now and the GIO part is here: #139

[sdroege]

Oh the other part was also in GIO, added to the existing PR