From aa810f018e9e65e996e99dd479147f5fc663a587 Mon Sep 17 00:00:00 2001
From: Mads Marquart <mads@marquart.dk>
Date: Tue, 30 Nov 2021 00:09:17 +0100
Subject: [PATCH] Fix CGDisplayCreateUUIDFromDisplayID linking (again)

See also https://github.com/rust-windowing/winit/pull/1626.

The `cocoa` crate links to AppKit, which made the symbol `CGDisplayCreateUUIDFromDisplayID` from ColorSync (which AppKit uses internally) available to us (on macOS 10.13 or above).

Lately something changed in rustc so that this no longer works, see https://github.com/rust-lang/rust/issues/91372. So instead, we link to AppKit directly within the `winit` crate, which, for now, allows us to use the private symbol.
---
 README.md                      | 10 ----------
 build.rs                       | 10 ----------
 src/platform_impl/macos/ffi.rs | 21 ++++++++++-----------
 3 files changed, 10 insertions(+), 31 deletions(-)
 delete mode 100644 build.rs

diff --git a/README.md b/README.md
index fcbc973973c..7a53a685c6a 100644
--- a/README.md
+++ b/README.md
@@ -119,13 +119,3 @@ 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.
-
diff --git a/build.rs b/build.rs
deleted file mode 100644
index a092e63631d..00000000000
--- a/build.rs
+++ /dev/null
@@ -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");
-    }
-}
diff --git a/src/platform_impl/macos/ffi.rs b/src/platform_impl/macos/ffi.rs
index 991b3f331d5..7d7968a21e3 100644
--- a/src/platform_impl/macos/ffi.rs
+++ b/src/platform_impl/macos/ffi.rs
@@ -165,20 +165,19 @@ pub const IO8BitOverlayPixels: &str = "O8";
 pub type CGWindowLevel = i32;
 pub type CGDisplayModeRef = *mut c_void;
 
-#[cfg_attr(
-    not(use_colorsync_cgdisplaycreateuuidfromdisplayid),
-    link(name = "CoreGraphics", kind = "framework")
-)]
-#[cfg_attr(
-    use_colorsync_cgdisplaycreateuuidfromdisplayid,
-    link(name = "ColorSync", kind = "framework")
-)]
-extern "C" {
-    pub fn CGDisplayCreateUUIDFromDisplayID(display: CGDirectDisplayID) -> CFUUIDRef;
-}
+// HACK:
+// `CGDisplayCreateUUIDFromDisplayID` moved from `CoreGraphics` to `ColorSync`
+// in macOS 10.13 (which is also where `ColorSync` was introduced).
+//
+// Since we want to support older versions, we can't link to `ColorSync`
+// directly. Fortunately `AppKit` links to `ColorSync` internally, so by
+// linking to `AppKit` in this crate, the symbol becomes available.
+#[link(name = "AppKit", kind = "framework")]
+extern "C" {}
 
 #[link(name = "CoreGraphics", kind = "framework")]
 extern "C" {
+    pub fn CGDisplayCreateUUIDFromDisplayID(display: CGDirectDisplayID) -> CFUUIDRef;
     pub fn CGRestorePermanentDisplayConfiguration();
     pub fn CGDisplayCapture(display: CGDirectDisplayID) -> CGError;
     pub fn CGDisplayRelease(display: CGDirectDisplayID) -> CGError;