Revert workaround with Class.forName and embed proguard rules to JAR resources instead

Author: qwwdfsad

README.md

@@ -129,17 +129,8 @@ coroutine dispatcher and also makes sure that in case of crashed coroutine with
 exception is logged before crashing Android application, similarly to the way uncaught exceptions in 
 threads are handled by Android runtime. 
 
-### ProGuard
-
-In obfuscated code, fields with different types can have the same names,
-and `AtomicReferenceFieldUpdater` may be unable to find the correct ones.
-To avoid field overloading by type during obfuscation, add this to your config:
-
-```
--keepclassmembernames class kotlinx.** {
-    volatile <fields>;
-}
-```
+### R8 and ProGuard
+If you are using R8 or ProGuard add the options from [coroutines.pro](core/kotlinx-coroutines-core/resources/META-INF/proguard/coroutines.pro) file to your rules.
 
 ## Building 
 

common/kotlinx-coroutines-core-common/src/CoroutineExceptionHandler.kt

@@ -4,7 +4,6 @@
 
 package kotlinx.coroutines
 
-import kotlinx.coroutines.internal.*
 import kotlin.coroutines.*
 
 internal expect fun handleCoroutineExceptionImpl(context: CoroutineContext, exception: Throwable)

core/kotlinx-coroutines-core/resources/META-INF/proguard/coroutines.pro

@@ -0,0 +1,8 @@
+# ServiceLoader support
+-keepnames class kotlinx.coroutines.internal.MainDispatcherFactory {}
+-keepnames class kotlinx.coroutines.CoroutineExceptionHandler {}
+
+# Most of volatile fields are updated with AFU and should not be mangled
+-keepclassmembernames class kotlinx.** {
+    volatile <fields>;
+}

core/kotlinx-coroutines-core/src/Dispatchers.kt

@@ -94,21 +94,7 @@ private object MainDispatcherLoader {
     val dispatcher: MainCoroutineDispatcher =
         MainDispatcherFactory::class.java.let { clz ->
             ServiceLoader.load(clz, clz.classLoader).toList()
-        }.maxBy { it.loadPriority }?.tryCreateDispatcher()
-            ?: (tryLoadAndroidDispatcher() ?: MissingMainCoroutineDispatcher(null))
-
-    private fun tryLoadAndroidDispatcher(): MainCoroutineDispatcher? {
-        /*
-         * Latest Android toolchain (androidx) *sometimes* mangles the name of the service loaded by ServiceLoader even if
-         * it is present in the manifest. To workaround it (we don't want our users to suffer) we optimistically
-         * try to load android factory manually (implementation is not mangled because it is marked with @Keep)
-         */
-        val dispatcher = kotlin.runCatching {
-            val clazz = Class.forName("kotlinx.coroutines.android.AndroidDispatcherFactory")
-            clazz.getMethod("getDispatcher")?.invoke(null) as MainCoroutineDispatcher
-        }
-        return dispatcher.getOrNull()
-    }
+        }.maxBy { it.loadPriority }?.tryCreateDispatcher() ?: MissingMainCoroutineDispatcher(null)
 
     /**
      * If anything goes wrong while trying to create main dispatcher (class not found,

ui/kotlinx-coroutines-android/animation-app/app/proguard-rules.pro

@@ -1,3 +1,5 @@
+-keepnames class kotlinx.coroutines.internal.MainDispatcherFactory {}
+-keepnames class kotlinx.coroutines.CoroutineExceptionHandler {}
 -keepclassmembernames class kotlinx.** {
     volatile <fields>;
 }

ui/kotlinx-coroutines-android/example-app/app/proguard-rules.pro

@@ -1,3 +1,5 @@
+-keepnames class kotlinx.coroutines.internal.MainDispatcherFactory {}
+-keepnames class kotlinx.coroutines.CoroutineExceptionHandler {}
 -keepclassmembernames class kotlinx.** {
     volatile <fields>;
 }