chore: Move part of error.rs to winit-core

Signed-off-by: John Nunley <dev@notgull.net>

Cargo.toml

@@ -5,3 +5,6 @@ members = [
     "winit-core"
 ]
 resolver = "2"
+
+[workspace.dependencies]
+winit-core = { path = "./winit-core", default-features = false, features = ["std"] }

winit-core/src/error.rs

@@ -0,0 +1,54 @@
+//! Common error types.
+
+use std::{error, fmt};
+
+/// The error type for when the requested operation is not supported by the backend.
+#[derive(Clone)]
+pub struct NotSupportedError {
+    _marker: (),
+}
+
+impl Default for NotSupportedError {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl NotSupportedError {
+    /// Create a new [`NotSupportedError`].
+    #[inline]
+    pub fn new() -> NotSupportedError {
+        NotSupportedError { _marker: () }
+    }
+}
+
+impl fmt::Debug for NotSupportedError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        f.debug_struct("NotSupportedError").finish()
+    }
+}
+
+impl fmt::Display for NotSupportedError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        f.pad("the requested operation is not supported by Winit")
+    }
+}
+
+impl error::Error for NotSupportedError {}
+
+#[cfg(test)]
+mod tests {
+    #![allow(clippy::redundant_clone)]
+
+    use super::*;
+
+    // Eat attributes for testing
+    #[test]
+    fn ensure_fmt_does_not_panic() {
+        let _ = format!(
+            "{:?}, {}",
+            NotSupportedError::new(),
+            NotSupportedError::new().clone()
+        );
+    }
+}

winit-core/src/lib.rs

@@ -1,11 +1,13 @@
 //! Base types for a windowing library.
-//! 
+//!
 //! This crate contains types, traits and basic functions from [`winit`] that are platform
 //! independent. It is intended to allow for other crates to build abstractions around [`winit`]
 //! without needing to pull in all of [`winit`]'s dependencies, as well as to provide an
 //! interface for alternative backends for [`winit`] to be constructed.
-//! 
+//!
 //! [`winit`]: https://docs.rs/winit
 
 #[cfg(any(not(feature = "std"), not(feature = "alloc")))]
 compile_error! { "no-std and no-alloc usage are not yet supported" }
+
+pub mod error;

winit/Cargo.toml

@@ -71,6 +71,7 @@ rwh_05 = { package = "raw-window-handle", version = "0.5.2", features = ["std"],
 rwh_06 = { package = "raw-window-handle", version = "0.6", features = ["std"], optional = true }
 serde = { version = "1", optional = true, features = ["serde_derive"] }
 smol_str = "0.2.0"
+winit-core.workspace = true
 
 [dev-dependencies]
 image = { version = "0.24.0", default-features = false, features = ["png"] }

winit/src/error.rs

@@ -1,6 +1,8 @@
+use crate::platform_impl;
 use std::{error, fmt};
 
-use crate::platform_impl;
+#[doc(inline)]
+pub use winit_core::error::NotSupportedError;
 
 // TODO: Rename
 /// An error that may be generated when requesting Winit state
@@ -14,12 +16,6 @@ pub enum ExternalError {
     Os(OsError),
 }
 
-/// The error type for when the requested operation is not supported by the backend.
-#[derive(Clone)]
-pub struct NotSupportedError {
-    _marker: (),
-}
-
 /// The error type for when the OS cannot perform the requested operation.
 #[derive(Debug)]
 pub struct OsError {
@@ -47,14 +43,6 @@ impl From<OsError> for EventLoopError {
     }
 }
 
-impl NotSupportedError {
-    #[inline]
-    #[allow(dead_code)]
-    pub(crate) fn new() -> NotSupportedError {
-        NotSupportedError { _marker: () }
-    }
-}
-
 impl OsError {
     #[allow(dead_code)]
     pub(crate) fn new(line: u32, file: &'static str, error: platform_impl::OsError) -> OsError {
@@ -88,18 +76,6 @@ impl fmt::Display for ExternalError {
     }
 }
 
-impl fmt::Debug for NotSupportedError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        f.debug_struct("NotSupportedError").finish()
-    }
-}
-
-impl fmt::Display for NotSupportedError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        f.pad("the requested operation is not supported by Winit")
-    }
-}
-
 impl fmt::Display for EventLoopError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         match self {
@@ -113,7 +89,6 @@ impl fmt::Display for EventLoopError {
 
 impl error::Error for OsError {}
 impl error::Error for ExternalError {}
-impl error::Error for NotSupportedError {}
 impl error::Error for EventLoopError {}
 
 #[cfg(test)]
@@ -125,11 +100,6 @@ mod tests {
     // Eat attributes for testing
     #[test]
     fn ensure_fmt_does_not_panic() {
-        let _ = format!(
-            "{:?}, {}",
-            NotSupportedError::new(),
-            NotSupportedError::new().clone()
-        );
         let _ = format!(
             "{:?}, {}",
             ExternalError::NotSupported(NotSupportedError::new()),