Dispatchers IO is now considered non-blocking context

See BlockingMethodInNonBlockingContextInspection

idea/src/org/jetbrains/kotlin/idea/inspections/blockingCallsDetection/CoroutineNonBlockingContextChecker.kt

@@ -24,9 +24,9 @@ import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.calls.callUtil.getParameterForArgument
 import org.jetbrains.kotlin.resolve.calls.checkers.isRestrictsSuspensionReceiver
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 
-
 class CoroutineNonBlockingContextChecker : NonBlockingContextChecker {
 
     override fun isApplicable(file: PsiFile): Boolean {
@@ -45,10 +45,11 @@ class CoroutineNonBlockingContextChecker : NonBlockingContextChecker {
             val callExpression = PsiTreeUtil.getParentOfType(containingArgument, KtCallExpression::class.java) ?: return false
             val call = callExpression.resolveToCall(BodyResolveMode.PARTIAL) ?: return false
 
-            val hasBlockingAnnotation = call.getFirstArgument()?.resolveToCall()
-                ?.resultingDescriptor?.annotations?.hasAnnotation(FqName(BLOCKING_CONTEXT_ANNOTATION))
-            if (hasBlockingAnnotation == true)
-                return false
+            val argumentDescriptor = call.getFirstArgument()?.resolveToCall()?.resultingDescriptor
+            val hasBlockingAnnotation = argumentDescriptor?.annotations?.hasAnnotation(FqName(BLOCKING_CONTEXT_ANNOTATION))
+            if (hasBlockingAnnotation == true) return false
+            val isIoDispatcherUsed = argumentDescriptor?.fqNameOrNull()?.asString() == IO_DISPATCHER_FQN
+            if (isIoDispatcherUsed) return false
 
             val parameterForArgument = call.getParameterForArgument(containingArgument) ?: return false
             val type = parameterForArgument.returnType ?: return false
@@ -69,5 +70,6 @@ class CoroutineNonBlockingContextChecker : NonBlockingContextChecker {
 
     companion object {
         private const val BLOCKING_CONTEXT_ANNOTATION = "org.jetbrains.annotations.BlockingContext"
+        private const val IO_DISPATCHER_FQN = "kotlinx.coroutines.Dispatchers.IO"
     }
 }

idea/testData/inspections/blockingCallsDetection/ContextCheck.kt

@@ -2,7 +2,6 @@
 
 import kotlin.coroutines.*
 import org.jetbrains.annotations.BlockingContext
-import kotlin.coroutines.experimental.buildSequence
 import java.lang.Thread.sleep
 
 suspend fun testFunction() {

idea/testData/inspections/blockingCallsDetection/DispatchersTypeCheck.kt

@@ -0,0 +1,28 @@
+@file:Suppress("UNUSED_PARAMETER")
+package kotlinx.coroutines
+
+import java.lang.Thread.sleep
+
+suspend fun withIoDispatcher() {
+    withContext(Dispatchers.IO) {
+        //no warning since IO dispatcher type used
+        Thread.sleep(42)
+    }
+
+    withContext(Dispatchers.Default) {
+        Thread.<warning descr="Inappropriate blocking method call">sleep</warning>(1)
+    }
+}
+
+class CoroutineDispatcher()
+object Dispatchers {
+    val IO: kotlinx.coroutines.CoroutineDispatcher = TODO()
+    val Default: kotlinx.coroutines.CoroutineDispatcher = TODO()
+}
+
+suspend fun <T> withContext(
+    context: CoroutineDispatcher,
+    f: suspend () -> T
+) {
+    TODO()
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/CoroutineNonBlockingontextDetectionTest.kt

@@ -10,11 +10,9 @@ import com.intellij.testFramework.LightProjectDescriptor
 import org.jetbrains.kotlin.idea.test.KotlinLightCodeInsightFixtureTestCase
 import org.jetbrains.kotlin.idea.test.KotlinWithJdkAndRuntimeLightProjectDescriptor
 import org.jetbrains.kotlin.idea.test.PluginTestCaseBase
-import org.jetbrains.kotlin.idea.test.configureCompilerOptions
 
-class CoroutineNonBlockingontextDetectionTest: KotlinLightCodeInsightFixtureTestCase() {
-    override fun getTestDataPath(): String
-            = PluginTestCaseBase.getTestDataPathBase() + "/inspections/blockingCallsDetection"
+class CoroutineNonBlockingContextDetectionTest : KotlinLightCodeInsightFixtureTestCase() {
+    override fun getTestDataPath(): String = PluginTestCaseBase.getTestDataPathBase() + "/inspections/blockingCallsDetection"
 
     override fun getProjectDescriptor(): LightProjectDescriptor = KotlinWithJdkAndRuntimeLightProjectDescriptor.INSTANCE
 
@@ -43,4 +41,9 @@ class CoroutineNonBlockingontextDetectionTest: KotlinLightCodeInsightFixtureTest
         myFixture.configureByFile("NestedFunctionsInsideSuspendLambda.kt")
         myFixture.testHighlighting(true, false, false, "NestedFunctionsInsideSuspendLambda.kt")
     }
+
+    fun testDispatchersTypeDetection() {
+        myFixture.configureByFile("DispatchersTypeCheck.kt")
+        myFixture.testHighlighting(true, false, false, "DispatchersTypeCheck.kt")
+    }
 }