glfw: macOS cross compilation with automatic setup

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

build.zig

@@ -19,9 +19,10 @@ fn thisDir() []const u8 {
 }
 
 pub const Options = struct {
-    GLES: bool = false,
-    OpenGL: bool = true,
     Vulkan: bool = true,
+    Metal: bool = true,
+    OpenGL: bool = false,
+    GLES: bool = false,
 };
 
 pub fn link(b: *Builder, step: *std.build.LibExeObjStep, options: Options) void {
@@ -58,14 +59,10 @@ pub fn link(b: *Builder, step: *std.build.LibExeObjStep, options: Options) void
 
                 // General sources
                 "upstream/glfw/src/monitor.c",
-                // "upstream/glfw/src/null_init.c",
-                // "upstream/glfw/src/null_joystick.c",
                 "upstream/glfw/src/init.c",
                 "upstream/glfw/src/vulkan.c",
-                // "upstream/glfw/src/null_monitor.c",
                 "upstream/glfw/src/input.c",
                 "upstream/glfw/src/osmesa_context.c",
-                // "upstream/glfw/src/null_window.c",
                 "upstream/glfw/src/egl_context.c",
                 "upstream/glfw/src/context.c",
                 "upstream/glfw/src/window.c",
@@ -111,12 +108,20 @@ fn linkGLFW(b: *Builder, step: *std.build.LibExeObjStep, options: Options) void
     switch (target.os.tag) {
         .windows => {},
         .macos => {
+            const sdk_root_dir = getSdkRoot(b.allocator, "sdk-macos-11.3") catch unreachable;
+            defer b.allocator.free(sdk_root_dir);
+
+            var sdk_root_frameworks = std.fs.path.join(b.allocator, &.{ sdk_root_dir, "root/System/Library/Frameworks" }) catch unreachable;
+            defer b.allocator.free(sdk_root_frameworks);
+            step.addFrameworkDir(sdk_root_frameworks);
+
+            var sdk_root_includes = std.fs.path.join(b.allocator, &.{ sdk_root_dir, "root/usr/include" }) catch unreachable;
+            defer b.allocator.free(sdk_root_includes);
+            step.addSystemIncludeDir(sdk_root_includes);
+
             step.linkFramework("Cocoa");
             step.linkFramework("IOKit");
             step.linkFramework("CoreFoundation");
-            if (options.GLES) {
-                step.linkSystemLibrary("GLESv2");
-            }
             if (options.OpenGL) {
                 step.linkFramework("OpenGL");
             }
@@ -125,4 +130,48 @@ fn linkGLFW(b: *Builder, step: *std.build.LibExeObjStep, options: Options) void
             // Assume Linux-like
         },
     }
-}
+}
+
+// Caller owns returned memory.
+fn getSdkRoot(allocator: *std.mem.Allocator, comptime name: []const u8) ![]const u8 {
+    const app_data_dir = try std.fs.getAppDataDir(allocator, "mach");
+    var sdk_root_dir = try std.fs.path.join(allocator, &.{ app_data_dir, name });
+    if (std.fs.openDirAbsolute(sdk_root_dir, .{})) {
+        return sdk_root_dir;
+    } else |err| return switch (err) {
+        error.FileNotFound => {
+            std.log.info("cloning required sdk..\ngit clone https://github.com/hexops/{s} '{s}'..\n", .{ name, sdk_root_dir });
+            if (std.mem.eql(u8, name, "sdk-macos-11.3")) {
+                if (!try confirmAppleSDKAgreement()) @panic("cannot continue");
+            }
+            try std.fs.cwd().makePath(app_data_dir);
+            const argv = &[_][]const u8{ "git", "clone", "https://github.com/hexops/" ++ name };
+            const child = try std.ChildProcess.init(argv, allocator);
+            child.cwd = app_data_dir;
+            child.stdin = std.io.getStdOut();
+            child.stderr = std.io.getStdErr();
+            child.stdout = std.io.getStdOut();
+            try child.spawn();
+            _ = try child.wait();
+            return sdk_root_dir;
+        },
+        else => err,
+    };
+}
+
+fn confirmAppleSDKAgreement() !bool {
+    if (std.mem.eql(u8, std.os.getenv("AGREE") orelse "", "true")) return true;
+    const stdin = std.io.getStdIn().reader();
+    const stdout = std.io.getStdOut().writer();
+    var buf: [10]u8 = undefined;
+    try stdout.print("This SDK is distributed under the terms of the Xcode and Apple SDKs agreement:\n", .{});
+    try stdout.print("  https://www.apple.com/legal/sla/docs/xcode.pdf\n", .{});
+    try stdout.print("\n", .{});
+    try stdout.print("Do you agree to those terms? [Y/n] ", .{});
+    if (try stdin.readUntilDelimiterOrEof(buf[0..], '\n')) |user_input| {
+        try stdout.print("\n", .{});
+        return std.mem.eql(u8, user_input, "y") or std.mem.eql(u8, user_input, "Y") or std.mem.eql(u8, user_input, "yes") or std.mem.eql(u8, user_input, "");
+    } else {
+        return false;
+    }
+}

src/main.zig

@@ -8,14 +8,13 @@ pub fn basicTest() void {
         @panic("failed to init");
     }
     const window = c.glfwCreateWindow(640, 480, "GLFW example", null, null);
-    if (window == null)
+    if (window == null) {
-    {
         c.glfwTerminate();
         @panic("failed to create window");
     }
 
     var start = std.time.milliTimestamp();
-    while (std.time.milliTimestamp() < start+3000 and c.glfwWindowShouldClose(window) != c.GLFW_TRUE) {
+    while (std.time.milliTimestamp() < start + 3000 and c.glfwWindowShouldClose(window) != c.GLFW_TRUE) {
         c.glfwPollEvents();
     }