macho: add uuid link test

lib/std/build/CheckObjectStep.zig

@@ -571,6 +571,12 @@ const MachODumper = struct {
                 });
             },
 
+            .UUID => {
+                const uuid = lc.cast(macho.uuid_command).?;
+                try writer.writeByte('\n');
+                try writer.print("uuid {x}", .{std.fmt.fmtSliceHexLower(&uuid.uuid)});
+            },
+
             else => {},
         }
     }

test/link.zig

@@ -170,6 +170,11 @@ fn addMachOCases(cases: *tests.StandaloneContext) void {
         .requires_symlinks = true,
     });
 
+    cases.addBuildFile("test/link/macho/uuid/build.zig", .{
+        .build_modes = false,
+        .requires_symlinks = true,
+    });
+
     cases.addBuildFile("test/link/macho/weak_library/build.zig", .{
         .build_modes = true,
         .requires_symlinks = true,

test/link/macho/uuid/build.zig

@@ -0,0 +1,52 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const Builder = std.build.Builder;
+const LibExeObjectStep = std.build.LibExeObjStep;
+
+pub fn build(b: *Builder) void {
+    const test_step = b.step("test", "Test");
+    test_step.dependOn(b.getInstallStep());
+
+    switch (builtin.cpu.arch) {
+        .aarch64 => {
+            testUuid(b, test_step, .ReleaseSafe, "eb1203019e453d808d4f1e71053af9af");
+            testUuid(b, test_step, .ReleaseFast, "eb1203019e453d808d4f1e71053af9af");
+            testUuid(b, test_step, .ReleaseSmall, "eb1203019e453d808d4f1e71053af9af");
+        },
+        .x86_64 => {
+            testUuid(b, test_step, .ReleaseSafe, "b3598e7c42dc38b0bd2975ead6e4ae85");
+            testUuid(b, test_step, .ReleaseFast, "b3598e7c42dc38b0bd2975ead6e4ae85");
+            testUuid(b, test_step, .ReleaseSmall, "1064b25eef4e3e6391866188b3dd7156");
+        },
+        else => unreachable,
+    }
+}
+
+fn testUuid(b: *Builder, test_step: *std.build.Step, mode: std.builtin.Mode, comptime exp: []const u8) void {
+    // The calculated UUID value is independent of debug info and so it should
+    // stay the same across builds.
+    {
+        const dylib = simpleDylib(b, mode);
+        const check_dylib = dylib.checkObject(.macho);
+        check_dylib.checkStart("cmd UUID");
+        check_dylib.checkNext("uuid " ++ exp);
+        test_step.dependOn(&check_dylib.step);
+    }
+    {
+        const dylib = simpleDylib(b, mode);
+        dylib.strip = true;
+        const check_dylib = dylib.checkObject(.macho);
+        check_dylib.checkStart("cmd UUID");
+        check_dylib.checkNext("uuid " ++ exp);
+        test_step.dependOn(&check_dylib.step);
+    }
+}
+
+fn simpleDylib(b: *Builder, mode: std.builtin.Mode) *LibExeObjectStep {
+    const dylib = b.addSharedLibrary("test", null, b.version(1, 0, 0));
+    dylib.setBuildMode(mode);
+    dylib.setTarget(.{ .os_tag = .macos });
+    dylib.addCSourceFile("test.c", &.{});
+    dylib.linkLibC();
+    return dylib;
+}

test/link/macho/uuid/test.c

@@ -0,0 +1,2 @@
+void test() {}
+