cleanup(platform): we don't need CGO anymore (#355)

* cleanup(platform): we don't need CGO anymore

Since go1.16, we have the `ios` port. So we can easily
disambiguate between ios and darwin.

This means we don't need to rely on CGO to correctly guess
whether we are on ios or darwin anymore.

So, now miniooni does not depend on a C compiler even
when you are not cross compiling.

* Update internal/platform/platform.go

internal/platform/platform.go

@@ -24,28 +24,20 @@ import "runtime"
 // has been disabled. In such case, the code will return "ios" when
 // using arm{,64} and "macos" when using x86{,_64}.
 func Name() string {
-	if name := cgoname(); name != "unknown" {
+	return name(runtime.GOOS)
-		return name
-	}
-	return puregoname(runtime.GOOS, runtime.GOARCH)
 }
 
-func puregoname(goos, goarch string) string {
+// name is a utility function for implementing Name.
+func name(goos string) string {
+	// Note: since go1.16 we have the ios port, so the ambiguity
+	// between ios and darwin is now gone.
+	//
+	// See https://golang.org/doc/go1.16#darwin
 	switch goos {
-	case "android", "linux", "windows":
+	case "android", "linux", "windows", "ios":
 		return goos
 	case "darwin":
-		return detectDarwin(goarch)
-	}
-	return "unknown"
-}
-
-func detectDarwin(goarch string) string {
-	switch goarch {
-	case "386", "amd64":
 		return "macos"
-	case "arm", "arm64":
-		return "ios"
 	}
 	return "unknown"
 }

internal/platform/platform_cgo.go

@@ -1,31 +0,0 @@
-// +build cgo
-
-package platform
-
-//
-// /* Guess the platform in which we are.
-//
-//     See: <https://sourceforge.net/p/predef/wiki/OperatingSystems/>
-//          <http://stackoverflow.com/a/18729350> */
-//
-//#if defined __ANDROID__
-//#  define OONI_PLATFORM "android"
-//#elif defined __linux__
-//#  define OONI_PLATFORM "linux"
-//#elif defined _WIN32
-//#  define OONI_PLATFORM "windows"
-//#elif defined __APPLE__
-//#  include <TargetConditionals.h>
-//#  if TARGET_OS_IPHONE
-//#    define OONI_PLATFORM "ios"
-//#  else
-//#    define OONI_PLATFORM "macos"
-//#  endif
-//#else
-//#  define OONI_PLATFORM "unknown"
-//#endif
-import "C"
-
-func cgoname() string {
-	return C.OONI_PLATFORM
-}

internal/platform/platform_otherwise.go

@@ -1,7 +0,0 @@
-// +build !cgo
-
-package platform
-
-func cgoname() string {
-	return "unknown"
-}

internal/platform/platform_test.go

@@ -16,51 +16,32 @@ func TestGood(t *testing.T) {
 	}
 }
 
-func TestPuregoname(t *testing.T) {
+func TestName(t *testing.T) {
 	var runtimevariables = []struct {
 		expected string
-		goarch   string
 		goos     string
 	}{{
 		expected: "android",
-		goarch:   "*",
 		goos:     "android",
 	}, {
 		expected: "ios",
-		goarch:   "arm64",
+		goos:     "ios",
-		goos:     "darwin",
-	}, {
-		expected: "ios",
-		goarch:   "arm",
-		goos:     "darwin",
 	}, {
 		expected: "linux",
-		goarch:   "*",
 		goos:     "linux",
 	}, {
 		expected: "macos",
-		goarch:   "amd64",
-		goos:     "darwin",
-	}, {
-		expected: "macos",
-		goarch:   "386",
 		goos:     "darwin",
 	}, {
 		expected: "unknown",
-		goarch:   "*",
 		goos:     "solaris",
-	}, {
-		expected: "unknown",
-		goarch:   "mips",
-		goos:     "darwin",
 	}, {
 		expected: "windows",
-		goarch:   "*",
 		goos:     "windows",
 	}}
 	for _, v := range runtimevariables {
-		t.Run(fmt.Sprintf("with %s/%s", v.goos, v.goarch), func(t *testing.T) {
+		t.Run(fmt.Sprintf("with %s", v.goos), func(t *testing.T) {
-			if puregoname(v.goos, v.goarch) != v.expected {
+			if name(v.goos) != v.expected {
 				t.Fatal("unexpected results")
 			}
 		})