func envInit()

in cmd/gomobile/env.go [157:281]

• 97 lines of code
• 20 McCabe index (conditional complexity)

func envInit() (err error) {
	// Setup the cross-compiler environments.
	if ndkRoot, err := ndkRoot(); err == nil {
		androidEnv = make(map[string][]string)
		if buildAndroidAPI < minAndroidAPI {
			return fmt.Errorf("gomobile requires Android API level >= %d", minAndroidAPI)
		}
		for arch, toolchain := range ndk {
			clang := toolchain.Path(ndkRoot, "clang")
			clangpp := toolchain.Path(ndkRoot, "clang++")
			if !buildN {
				tools := []string{clang, clangpp}
				if runtime.GOOS == "windows" {
					// Because of https://github.com/android-ndk/ndk/issues/920,
					// we require r19c, not just r19b. Fortunately, the clang++.cmd
					// script only exists in r19c.
					tools = append(tools, clangpp+".cmd")
				}
				for _, tool := range tools {
					_, err = os.Stat(tool)
					if err != nil {
						return fmt.Errorf("No compiler for %s was found in the NDK (tried %s). Make sure your NDK version is >= r19c. Use `sdkmanager --update` to update it.", arch, tool)
					}
				}
			}
			androidEnv[arch] = []string{
				"GOOS=android",
				"GOARCH=" + arch,
				"CC=" + clang,
				"CXX=" + clangpp,
				"CGO_ENABLED=1",
			}
			if arch == "arm" {
				androidEnv[arch] = append(androidEnv[arch], "GOARM=7")
			}
		}
	}

	if !xcodeAvailable() {
		return nil
	}

	appleNM = "nm"
	appleEnv = make(map[string][]string)
	for _, platform := range applePlatforms {
		for _, arch := range platformArchs(platform) {
			var env []string
			var goos, sdk, clang, cflags string
			var err error
			switch platform {
			case "ios":
				goos = "ios"
				sdk = "iphoneos"
				clang, cflags, err = envClang(sdk)
				cflags += " -miphoneos-version-min=" + buildIOSVersion
				cflags += " -fembed-bitcode"
			case "iossimulator":
				goos = "ios"
				sdk = "iphonesimulator"
				clang, cflags, err = envClang(sdk)
				cflags += " -mios-simulator-version-min=" + buildIOSVersion
				cflags += " -fembed-bitcode"
			case "maccatalyst":
				// Mac Catalyst is a subset of iOS APIs made available on macOS
				// designed to ease porting apps developed for iPad to macOS.
				// See https://developer.apple.com/mac-catalyst/.
				// Because of this, when building a Go package targeting maccatalyst,
				// GOOS=darwin (not ios). To bridge the gap and enable maccatalyst
				// packages to be compiled, we also specify the "ios" build tag.
				// To help discriminate between darwin, ios, macos, and maccatalyst
				// targets, there is also a "maccatalyst" tag.
				// Some additional context on this can be found here:
				// https://stackoverflow.com/questions/12132933/preprocessor-macro-for-os-x-targets/49560690#49560690
				goos = "darwin"
				sdk = "macosx"
				clang, cflags, err = envClang(sdk)
				// TODO(ydnar): the following 3 lines MAY be needed to compile
				// packages or apps for maccatalyst. Commenting them out now in case
				// it turns out they are necessary. Currently none of the example
				// apps will build for macos or maccatalyst because they have a
				// GLKit dependency, which is deprecated on all Apple platforms, and
				// broken on maccatalyst (GLKView isn’t available).
				// sysroot := strings.SplitN(cflags, " ", 2)[1]
				// cflags += " -isystem " + sysroot + "/System/iOSSupport/usr/include"
				// cflags += " -iframework " + sysroot + "/System/iOSSupport/System/Library/Frameworks"
				switch arch {
				case "amd64":
					cflags += " -target x86_64-apple-ios" + buildIOSVersion + "-macabi"
				case "arm64":
					cflags += " -target arm64-apple-ios" + buildIOSVersion + "-macabi"
					cflags += " -fembed-bitcode"
				}
			case "macos":
				goos = "darwin"
				sdk = "macosx" // Note: the SDK is called "macosx", not "macos"
				clang, cflags, err = envClang(sdk)
				if arch == "arm64" {
					cflags += " -fembed-bitcode"
				}
			default:
				panic(fmt.Errorf("unknown Apple target: %s/%s", platform, arch))
			}

			if err != nil {
				return err
			}

			env = append(env,
				"GOOS="+goos,
				"GOARCH="+arch,
				"GOFLAGS="+"-tags="+strings.Join(platformTags(platform), ","),
				"CC="+clang,
				"CXX="+clang+"++",
				"CGO_CFLAGS="+cflags+" -arch "+archClang(arch),
				"CGO_CXXFLAGS="+cflags+" -arch "+archClang(arch),
				"CGO_LDFLAGS="+cflags+" -arch "+archClang(arch),
				"CGO_ENABLED=1",
				"DARWIN_SDK="+sdk,
			)
			appleEnv[platform+"/"+arch] = env
		}
	}

	return nil
}