KT-6646, KT-10482:

when a method (or a property getter) returns Nothing, emit
  ACONST_NULL
  ATHROW
after a call so that class files verifier knows that this is an exit point in a method.
Note that if an inline method returning Nothing throws an exception explicitly
(or via a chain of inline methods), this code will be deleted by DCE.

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -2420,6 +2420,12 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
         }
 
         callGenerator.genCall(callableMethod, resolvedCall, defaultMaskWasGenerated, this);
+
+        KotlinType returnType = resolvedCall.getResultingDescriptor().getReturnType();
+        if (returnType != null && KotlinBuiltIns.isNothing(returnType)) {
+            v.aconst(null);
+            v.athrow();
+        }
     }
 
     @NotNull

compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java

@@ -23,6 +23,7 @@ import kotlin.jvm.functions.Function1;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.builtins.PrimitiveType;
 import org.jetbrains.kotlin.codegen.intrinsics.IntrinsicMethods;
 import org.jetbrains.kotlin.codegen.intrinsics.JavaClassProperty;
@@ -45,6 +46,7 @@ import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmMethodParameterKind;
 import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmMethodParameterSignature;
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue;
 import org.jetbrains.kotlin.synthetic.SamAdapterExtensionFunctionDescriptor;
+import org.jetbrains.kotlin.types.KotlinType;
 import org.jetbrains.org.objectweb.asm.Label;
 import org.jetbrains.org.objectweb.asm.Type;
 import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter;
@@ -1086,6 +1088,12 @@ public abstract class StackValue {
             else {
                 getter.genInvokeInstruction(v);
                 coerce(getter.getReturnType(), type, v);
+
+                KotlinType returnType = descriptor.getReturnType();
+                if (returnType != null && KotlinBuiltIns.isNothing(returnType)) {
+                    v.aconst(null);
+                    v.athrow();
+                }
             }
         }
 

compiler/testData/codegen/box/controlStructures/returnsNothing/ifElse.kt

@@ -0,0 +1,14 @@
+var flag = true
+
+fun exit(): Nothing = null!!
+
+fun box(): String {
+    val a: String
+    if (flag) {
+        a = "OK"
+    }
+    else {
+        exit()
+    }
+    return a
+}

compiler/testData/codegen/box/controlStructures/returnsNothing/inlineMethod.kt

@@ -0,0 +1,12 @@
+inline fun exit(): Nothing = null!!
+
+fun box(): String {
+    val a: String
+    try {
+        a = "OK"
+    }
+    catch (e: Exception) {
+        exit()
+    }
+    return a
+}

compiler/testData/codegen/box/controlStructures/returnsNothing/propertyGetter.kt

@@ -0,0 +1,16 @@
+var flag = true
+
+object Test {
+    val magic: Nothing get() = null!!
+}
+
+fun box(): String {
+    val a: String
+    if (flag) {
+        a = "OK"
+    }
+    else {
+        Test.magic
+    }
+    return a
+}

compiler/testData/codegen/box/controlStructures/returnsNothing/tryCatch.kt

@@ -0,0 +1,12 @@
+fun exit(): Nothing = null!!
+
+fun box(): String {
+    val a: String
+    try {
+        a = "OK"
+    }
+    catch (e: Exception) {
+        exit()
+    }
+    return a
+}

compiler/testData/codegen/box/controlStructures/returnsNothing/when.kt

@@ -0,0 +1,14 @@
+fun exit(): Nothing = null!!
+
+var x = 0
+
+fun box(): String {
+    val a: String
+    when (x) {
+        0 -> a = "OK"
+        1 -> a = "???"
+        2 -> exit()
+        else -> exit()
+    }
+    return a
+}

compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing1.kt

@@ -0,0 +1,16 @@
+// NB '!!' uses Intrinsics.throwNpe()
+inline fun exit(): Nothing = null!!
+
+fun box(): String {
+    val a: String
+    try {
+        a = "OK"
+    }
+    catch (e: Exception) {
+        exit()
+        // ATHROW
+    }
+    return a
+}
+
+// 1 ATHROW

compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing2.kt

@@ -0,0 +1,16 @@
+inline fun exit(): Nothing =
+        throw RuntimeException() // ATHROW
+
+fun box(): String {
+    val a: String
+    try {
+        a = "OK"
+    }
+    catch (e: Exception) {
+        exit() // ATHROW inlined
+        // no ATHROW (removed as dead code)
+    }
+    return a
+}
+
+// 2 ATHROW

compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing3.kt

@@ -0,0 +1,17 @@
+inline fun exit(): Nothing = null!!
+inline fun exita(): Nothing = exit() // ATHROW
+inline fun exitb(): Nothing = exita() // ATHROW
+inline fun exitc(): Nothing = exitb() // ATHROW
+
+fun box(): String {
+    val a: String
+    try {
+        a = "OK"
+    }
+    catch (e: Exception) {
+        exitc() // ATHROW
+    }
+    return a
+}
+
+// 4 ATHROW

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -706,6 +706,24 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/bytecodeText/inline"), Pattern.compile("^(.+)\\.kt$"), true);
         }
 
+        @TestMetadata("inlineReturnsNothing1.kt")
+        public void testInlineReturnsNothing1() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing1.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("inlineReturnsNothing2.kt")
+        public void testInlineReturnsNothing2() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing2.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("inlineReturnsNothing3.kt")
+        public void testInlineReturnsNothing3() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing3.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("noSynAccessor.kt")
         public void testNoSynAccessor() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/inline/noSynAccessor.kt");

compiler/tests/org/jetbrains/kotlin/codegen/generated/BlackBoxCodegenTestGenerated.java

@@ -2422,6 +2422,45 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             }
         }
 
+        @TestMetadata("compiler/testData/codegen/box/controlStructures/returnsNothing")
+        @TestDataPath("$PROJECT_ROOT")
+        @RunWith(JUnit3RunnerWithInners.class)
+        public static class ReturnsNothing extends AbstractBlackBoxCodegenTest {
+            public void testAllFilesPresentInReturnsNothing() throws Exception {
+                KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/controlStructures/returnsNothing"), Pattern.compile("^(.+)\\.kt$"), true);
+            }
+
+            @TestMetadata("ifElse.kt")
+            public void testIfElse() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/controlStructures/returnsNothing/ifElse.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("inlineMethod.kt")
+            public void testInlineMethod() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/controlStructures/returnsNothing/inlineMethod.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("propertyGetter.kt")
+            public void testPropertyGetter() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/controlStructures/returnsNothing/propertyGetter.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("tryCatch.kt")
+            public void testTryCatch() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/controlStructures/returnsNothing/tryCatch.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("when.kt")
+            public void testWhen() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/controlStructures/returnsNothing/when.kt");
+                doTest(fileName);
+            }
+        }
+
         @TestMetadata("compiler/testData/codegen/box/controlStructures/tryCatchInExpressions")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)