From f36f12713293eb54f25b2ec42cf70627f9125342 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 ApplicationServices/ColorSync (which AppKit uses internally) available to us (on macOS 10.8 or above).

However, this does not work on macOS 10.7; instead, we should just link to ApplicationServices directly!
---
 README.md                      | 10 ----------
 build.rs                       | 10 ----------
 src/platform_impl/macos/ffi.rs | 16 ++++++++--------
 3 files changed, 8 insertions(+), 28 deletions(-)
 delete mode 100644 build.rs

diff --git a/README.md b/README.md
index 1e358c586a..e97e29276d 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 a092e63631..0000000000
--- 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 991b3f331d..6f210ac1bd 100644
--- a/src/platform_impl/macos/ffi.rs
+++ b/src/platform_impl/macos/ffi.rs
@@ -165,14 +165,14 @@ 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")
-)]
+// `CGDisplayCreateUUIDFromDisplayID` comes from the `ColorSync` framework.
+// However, that framework was only introduced "publicly" in macOS 10.13.
+//
+// Since we want to support older versions, we can't link to `ColorSync`
+// 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
+#[link(name = "ApplicationServices", kind = "framework")]
 extern "C" {
     pub fn CGDisplayCreateUUIDFromDisplayID(display: CGDirectDisplayID) -> CFUUIDRef;
 }