Fix build with Zig 0.15.2

Author: jayschwa

build.zig

@@ -67,27 +67,22 @@ pub fn build(b: *std.Build) void {
             const cache_include = std.fs.path.join(b.allocator, &.{ b.sysroot.?, "cache", "sysroot", "include" }) catch @panic("Out of memory");
             defer b.allocator.free(cache_include);
 
+            // TODO: Remove compatibility shim when minimum Zig version is 0.16.0.
             if (@hasDecl(std.Io, "Dir")) {
-                // v0.16 -> Dir moved to std.Io
-                const open_dir_opts: std.Io.Dir.OpenOptions = .{
+                // Zig 0.16.0-dev
+                var dir = std.Io.Dir.openDirAbsolute(mod.owner.graph.io, cache_include, .{
                     .access_sub_paths = true,
                     .follow_symlinks = false,
-                };
-
-                var dir = std.Io.Dir.openDirAbsolute(mod.owner.graph.io, cache_include, open_dir_opts) catch @panic("No emscripten cache. Generate it!");
-
+                }) catch @panic("No emscripten cache. Generate it!");
                 dir.close(mod.owner.graph.io);
             } else if (@hasDecl(std.fs, "Dir")) {
-                // <=0.15.2 -> Dir on std.fs
-                const open_dir_opts: std.fs.Dir.OpenOptions = .{
+                // Zig 0.15.x
+                var dir = std.fs.openDirAbsolute(cache_include, .{
                     .access_sub_paths = true,
-                    .follow_symlinks = false,
-                };
-
-                var dir = std.fs.openDirAbsolute(cache_include, open_dir_opts) catch @panic("No emscripten cache. Generate it!");
-
+                    .no_follow = true,
+                }) catch @panic("No emscripten cache. Generate it!");
                 dir.close();
-            }
+            } else @compileError("Fix `openDirAbsolute` compatibility shim");
 
             mod.addIncludePath(.{ .cwd_relative = cache_include });
         },