Explicitly specify minimum supported rust version

This should help with distributing apps using winit.

Fixes #1075.

Author: kchibisov

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust_version: [stable, nightly]
+        rust_version: [1.57.0, stable, nightly]
         platform:
           # Note: Make sure that we test all the `docs.rs` targets defined in Cargo.toml!
           - { target: x86_64-pc-windows-msvc,   os: windows-latest,  }
@@ -103,7 +103,7 @@ jobs:
 
     - name: Lint with clippy
       shell: bash
-      if: (matrix.rust_version != 'nightly') && !contains(matrix.platform.options, '--no-default-features')
+      if: (matrix.rust_version == '1.57.0') && !contains(matrix.platform.options, '--no-default-features')
       run: cargo clippy --all-targets --target ${{ matrix.platform.target }} $OPTIONS --features $FEATURES -- -Dwarnings
 
     - name: Build with serde enabled

CHANGELOG.md

@@ -8,6 +8,8 @@ And please only add new entries to the top of this list, right below the `# Unre
 
 # Unreleased
 
+- The minimum supported rust version was lowered to `1.57.0` and now explicitly tested.
+
 # 0.27.0 (2022-07-26)
 
 - On Windows, fix hiding a maximized window.

CONTRIBUTING.md

@@ -20,6 +20,7 @@ your description of the issue as detailed as possible:
 
 When making a code contribution to winit, before opening your pull request, please make sure that:
 
+- your patch builds with Winit's minimal supported rust version - Rust 1.57.0.
 - you tested your modifications on all the platforms impacted, or if not possible detail which platforms
   were not tested, and what should be tested, so that a maintainer or another contributor can test them
 - you updated any relevant documentation in winit

Cargo.toml

@@ -10,6 +10,7 @@ readme = "README.md"
 repository = "https://github.com/rust-windowing/winit"
 documentation = "https://docs.rs/winit"
 categories = ["gui"]
+rust-version = "1.57.0"
 
 [package.metadata.docs.rs]
 features = ["serde"]

examples/fullscreen.rs

@@ -59,12 +59,12 @@ fn main() {
                     }
                     VirtualKeyCode::F => {
                         let fullscreen = Some(Fullscreen::Exclusive(mode.clone()));
-                        println!("Setting mode: {fullscreen:?}");
+                        println!("Setting mode: {:?}", fullscreen);
                         window.set_fullscreen(fullscreen);
                     }
                     VirtualKeyCode::B => {
                         let fullscreen = Some(Fullscreen::Borderless(Some(monitor.clone())));
-                        println!("Setting mode: {fullscreen:?}");
+                        println!("Setting mode: {:?}", fullscreen);
                         window.set_fullscreen(fullscreen);
                     }
                     VirtualKeyCode::S => {

src/platform_impl/linux/mod.rs

@@ -587,7 +587,8 @@ impl Window {
 
 /// Hooks for X11 errors.
 #[cfg(feature = "x11")]
-pub(crate) static mut XLIB_ERROR_HOOKS: Mutex<Vec<XlibErrorHook>> = Mutex::new(Vec::new());
+pub(crate) static mut XLIB_ERROR_HOOKS: Lazy<Mutex<Vec<XlibErrorHook>>> =
+    Lazy::new(|| Mutex::new(Vec::new()));
 
 #[cfg(feature = "x11")]
 unsafe extern "C" fn x_error_callback(