    const std = @import("std");
    const mem = std.mem;
    const Allocator = mem.Allocator;
    const Target = std.Target;
    const Version = std.SemanticVersion;

    pub const macos = @import("darwin/macos.zig");

    /// Check if SDK is installed on Darwin without triggering CLT installation popup window.
    /// Note: simply invoking `xcrun` will inevitably trigger the CLT installation popup.
    /// Therefore, we resort to invoking `xcode-select --print-path` and checking
    /// if the status is nonzero.
    /// stderr from xcode-select is ignored.
    /// If error.OutOfMemory occurs in Allocator, this function returns null.
    pub fn isSdkInstalled(allocator: Allocator) bool {
        const result = std.process.Child.run(.{
            .allocator = allocator,
            .argv = &.{ "/usr/bin/xcode-select", "--print-path" },
        }) catch return false;

        defer {
            allocator.free(result.stderr);
            allocator.free(result.stdout);
        }

        return switch (result.term) {
            .Exited => |code| if (code == 0) result.stdout.len > 0 else false,
            else => false,
        };
    }

    /// Detect SDK on Darwin.
    /// Calls `xcrun --sdk <target_sdk> --show-sdk-path` which fetches the path to the SDK.
    /// Caller owns the memory.
    /// stderr from xcrun is ignored.
    /// If error.OutOfMemory occurs in Allocator, this function returns null.
    pub fn getSdk(allocator: Allocator, target: Target) ?[]const u8 {
        const is_simulator_abi = target.abi == .simulator;
        const sdk = switch (target.os.tag) {
            .macos => "macosx",
            .ios => if (is_simulator_abi) "iphonesimulator" else "iphoneos",
            .watchos => if (is_simulator_abi) "watchsimulator" else "watchos",
            .tvos => if (is_simulator_abi) "appletvsimulator" else "appletvos",
            else => return null,
        };
        const argv = &[_][]const u8{ "/usr/bin/xcrun", "--sdk", sdk, "--show-sdk-path" };
        const result = std.process.Child.run(.{ .allocator = allocator, .argv = argv }) catch return null;
        defer {
            allocator.free(result.stderr);
            allocator.free(result.stdout);
        }
        switch (result.term) {
            .Exited => |code| if (code != 0) return null,
            else => return null,
        }
        return allocator.dupe(u8, mem.trimRight(u8, result.stdout, "\r\n")) catch null;
    }

    test {
        _ = macos;
    }