new opengl function calls for stage2

src/Window.zig

@@ -191,7 +191,10 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
     try glfw.swapInterval(1);
 
     // Load OpenGL bindings
-    const version = try gl.glad.load(glfw.getProcAddress);
+    const version = try gl.glad.load(switch (builtin.zig_backend) {
+        .stage1 => glfw.getProcAddress,
+        else => &glfw.getProcAddress,
+    });
     log.info("loaded OpenGL {}.{}", .{
         gl.glad.versionMajor(version),
         gl.glad.versionMinor(version),

src/opengl/glad.zig

@@ -1,13 +1,17 @@
+const std = @import("std");
 const c = @import("c.zig");
 
 /// Initialize Glad. This is guaranteed to succeed if no errors are returned.
 /// The getProcAddress param is an anytype so that we can accept multiple
 /// forms of the function depending on what we're interfacing with.
 pub fn load(getProcAddress: anytype) !c_int {
+    const GlProc = std.meta.FnPtr(fn () callconv(.C) void);
+    const GlfwFn = std.meta.FnPtr(fn ([*:0]const u8) callconv(.C) ?GlProc);
+
     const res = switch (@TypeOf(getProcAddress)) {
         // glfw
-        fn ([*:0]const u8) callconv(.C) ?fn () callconv(.C) void => c.gladLoadGL(@ptrCast(
+        GlfwFn => c.gladLoadGL(@ptrCast(
-            fn ([*c]const u8) callconv(.C) ?fn () callconv(.C) void,
+            std.meta.FnPtr(fn ([*c]const u8) callconv(.C) ?GlProc),
             getProcAddress,
         )),