Remove WINIT_LINK_COLORSYNC (no longer needed) (#2136)

Since https://github.com/rust-windowing/winit/pull/2078 we link to `ApplicationServices`, which contains the `CGDisplayCreateUUIDFromDisplayID` symbol in all versions.

CHANGELOG.md

@@ -8,6 +8,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 
 # Unreleased
 
+- Remove no longer needed `WINIT_LINK_COLORSYNC` environment variable.
 - **Breaking:** Rename the `Exit` variant of `ControlFlow` to `ExitWithCode`, which holds a value to control the exit code after running. Add an `Exit` constant which aliases to `ExitWithCode(0)` instead to avoid major breakage. This shouldn't affect most existing programs.
 
 # 0.26.1 (2022-01-05)

README.md

@@ -118,13 +118,3 @@ fn main() {
 ```
 
 And run the application with `cargo apk run --example request_redraw_threaded`
-
-#### MacOS
-
-To ensure compatibility with older MacOS systems, winit links to
-CGDisplayCreateUUIDFromDisplayID through the CoreGraphics framework.
-However, under certain setups this function is only available to be linked
-through the newer ColorSync framework. So, winit provides the
-`WINIT_LINK_COLORSYNC` environment variable which can be set to `1` or `true`
-while compiling to enable linking via ColorSync.
-

build.rs

@@ -1,10 +0,0 @@
-fn main() {
-    // If building for macos and WINIT_LINK_COLORSYNC is set to true
-    // use CGDisplayCreateUUIDFromDisplayID from ColorSync instead of CoreGraphics
-    if std::env::var("CARGO_CFG_TARGET_OS").map_or(false, |os| os == "macos")
-        && std::env::var("WINIT_LINK_COLORSYNC")
-            .map_or(false, |v| v == "1" || v.eq_ignore_ascii_case("true"))
-    {
-        println!("cargo:rustc-cfg=use_colorsync_cgdisplaycreateuuidfromdisplayid");
-    }
-}

src/platform_impl/macos/ffi.rs

@@ -171,16 +171,7 @@ pub type CGDisplayModeRef = *mut c_void;
 // directly. Fortunately, it has always been available as a subframework of
 // `ApplicationServices`, see:
 // https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/OSX_Technology_Overview/SystemFrameworks/SystemFrameworks.html#//apple_ref/doc/uid/TP40001067-CH210-BBCFFIEG
-//
-// TODO: Remove the WINIT_LINK_COLORSYNC hack, it is probably not needed.
-#[cfg_attr(
-    not(use_colorsync_cgdisplaycreateuuidfromdisplayid),
-    link(name = "ApplicationServices", kind = "framework")
-)]
-#[cfg_attr(
-    use_colorsync_cgdisplaycreateuuidfromdisplayid,
-    link(name = "ColorSync", kind = "framework")
-)]
+#[link(name = "ApplicationServices", kind = "framework")]
 extern "C" {
     pub fn CGDisplayCreateUUIDFromDisplayID(display: CGDirectDisplayID) -> CFUUIDRef;
 }