Bug: Custom metadata referencing windows::Win32::Foundation::BOOL fails to build with missing Debug trait

[wravery]

Which crate is this about?

windows

Crate version

0.29.0

Summary

This is the generated windows.rs file from when I tried to migrate https://github.com/wravery/webview2-rs/tree/next to 0.29.0:

                impl ::core::fmt::Debug for COREWEBVIEW2_PHYSICAL_KEY_STATUS {
                    fn fmt(&self, fmt: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
                        fmt.debug_struct("COREWEBVIEW2_PHYSICAL_KEY_STATUS")
                            .field("RepeatCount", &self.RepeatCount)
                            .field("ScanCode", &self.ScanCode)
                            .field("IsExtendedKey", &self.IsExtendedKey)
                            .field("IsMenuKeyDown", &self.IsMenuKeyDown)
                            .field("WasKeyDown", &self.WasKeyDown)
                            .field("IsKeyReleased", &self.IsKeyReleased)
                            .finish()
                    }
                }

Expected behavior

It should build just fine. It doesn't, because it complains that windows::Win32::Foundation::BOOL is missing an implementation of Debug, so it can't compile this function for IsExtendedKey or the other BOOL members in this struct.

Actual behavior

error[E0277]: `BOOL` doesn't implement `Debug`
   --> C:\repos\wravery\webview2-rs\target\debug\build\webview2-com-sys-bb3de26d494647cb\out/windows.rs:577:53
    |
577 | ...                   .field("IsExtendedKey", &self.IsExtendedKey)
    |                                               ^^^^^^^^^^^^^^^^^^^ `BOOL` cannot be formatted using `{:?}` because it doesn't implement `Debug`
    |
    = help: the trait `Debug` is not implemented for `BOOL`
    = note: required for the cast to the object type `dyn Debug`

error[E0277]: `BOOL` doesn't implement `Debug`
   --> C:\repos\wravery\webview2-rs\target\debug\build\webview2-com-sys-bb3de26d494647cb\out/windows.rs:578:53
    |
578 | ...                   .field("IsMenuKeyDown", &self.IsMenuKeyDown)
    |                                               ^^^^^^^^^^^^^^^^^^^ `BOOL` cannot be formatted using `{:?}` because it doesn't implement `Debug`
    |
    = help: the trait `Debug` is not implemented for `BOOL`
    = note: required for the cast to the object type `dyn Debug`

error[E0277]: `BOOL` doesn't implement `Debug`
   --> C:\repos\wravery\webview2-rs\target\debug\build\webview2-com-sys-bb3de26d494647cb\out/windows.rs:579:50
    |
579 | ...                   .field("WasKeyDown", &self.WasKeyDown)
    |                                            ^^^^^^^^^^^^^^^^ `BOOL` cannot be formatted using `{:?}` because it doesn't implement `Debug`
    |
    = help: the trait `Debug` is not implemented for `BOOL`
    = note: required for the cast to the object type `dyn Debug`

error[E0277]: `BOOL` doesn't implement `Debug`
   --> C:\repos\wravery\webview2-rs\target\debug\build\webview2-com-sys-bb3de26d494647cb\out/windows.rs:580:53
    |
580 | ...                   .field("IsKeyReleased", &self.IsKeyReleased)
    |                                               ^^^^^^^^^^^^^^^^^^^ `BOOL` cannot be formatted using `{:?}` because it doesn't implement `Debug`
    |
    = help: the trait `Debug` is not implemented for `BOOL`
    = note: required for the cast to the object type `dyn Debug`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `webview2-com-sys` due to 4 previous errors
warning: build failed, waiting for other jobs to finish...
error: build failed

Additional comments

This repros with the latest stable toolchain:

> rustc --version
rustc 1.57.0 (f1edd0429 2021-11-29)

[kennykerr]

Ah, the build/generate macros are still based on the old gen crate while everything else has moved over to the new bindgen crate. That's what's causing the discrepancy. I'll add a test for this and push out a fix as soon as I get a moment.

By the way, the build/generate macros will also soon be removed.

[wravery]

By the way, the build/generate macros will also soon be removed.

Should I replace that with something else?

[kennykerr]

Yes, the underlying code gen library used by the windows/windows-sys crates is now available here:

https://crates.io/crates/windows-bindgen
https://docs.rs/windows-bindgen

As you can see, it is really simple. Here's how you might use it to generate individual types:

https://github.com/microsoft/windows-rs/blob/master/crates/tools/bindings/src/main.rs

Or entire namespaces:

https://github.com/microsoft/windows-rs/blob/master/crates/tools/api/src/main.rs

Still testing and working out wrinkles, which is why the old build/generate macros are still around temporarily.