Change contract of getDelegationCall to @NotNull

Its existence guaranteed by parser

compiler/frontend/src/org/jetbrains/kotlin/cfg/JetControlFlowProcessor.java

@@ -1441,8 +1441,7 @@ public class JetControlFlowProcessor {
             processParameters(constructor.getValueParameters());
             generateCallOrMarkUnresolved(constructor.getDelegationCall());
 
-            if (constructor.getDelegationCall() != null && !constructor.getDelegationCall().isCallToThis()
+            if (!constructor.getDelegationCall().isCallToThis()) {
-            ) {
                 generateClassOrObjectInitializers(classOrObject);
             }
 

compiler/frontend/src/org/jetbrains/kotlin/psi/JetPsiFactory.kt

@@ -363,7 +363,7 @@ public class JetPsiFactory(private val project: Project) {
 
     public fun createConstructorDelegationCall(text: String): JetConstructorDelegationCall {
         val colonOrEmpty = if (text.isEmpty()) "" else ": "
-        return createClass("class A { constructor()$colonOrEmpty$text {}").getSecondaryConstructors().first().getDelegationCall()!!
+        return createClass("class A { constructor()$colonOrEmpty$text {}").getSecondaryConstructors().first().getDelegationCall()
     }
 
     public inner class IfChainBuilder() {

compiler/frontend/src/org/jetbrains/kotlin/psi/JetSecondaryConstructor.java

@@ -172,14 +172,14 @@ public class JetSecondaryConstructor extends JetDeclarationStub<KotlinPlaceHolde
         throw new IncorrectOperationException("setName to constructor");
     }
 
-    @Nullable
+    @NotNull
     public JetConstructorDelegationCall getDelegationCall() {
         return findChildByClass(JetConstructorDelegationCall.class);
     }
 
     public boolean hasEmptyDelegationCall() {
         JetConstructorDelegationCall call = getDelegationCall();
-        return call != null && call.isEmpty();
+        return call.isEmpty();
     }
 
     @NotNull
@@ -192,7 +192,7 @@ public class JetSecondaryConstructor extends JetDeclarationStub<KotlinPlaceHolde
         JetPsiFactory psiFactory = new JetPsiFactory(getProject());
         JetConstructorDelegationCall current = getDelegationCall();
 
-        assert current != null && current.isEmpty()
+        assert current.isEmpty()
                 : "Method should not be called with non-existing or non-empty delegation call: " + getText();
         current.delete();
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java

@@ -217,7 +217,8 @@ public class BodyResolver {
             PsiElement constructorToReport = DescriptorToSourceUtils.descriptorToDeclaration(currentConstructor);
             if (constructorToReport != null) {
                 JetConstructorDelegationCall call = ((JetSecondaryConstructor) constructorToReport).getDelegationCall();
-                assert call != null && call.getCalleeExpression() != null : "resolved call and it's callee can't be null";
+                assert call.getCalleeExpression() != null
+                        : "Callee expression of delegation call should not be null on cycle as there should be explicit 'this' calls";
                 trace.report(CYCLIC_CONSTRUCTOR_DELEGATION_CALL.on(call.getCalleeExpression()));
             }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CallResolver.java

@@ -301,11 +301,10 @@ public class CallResolver {
     public OverloadResolutionResults<FunctionDescriptor> resolveConstructorDelegationCall(
             @NotNull BindingTrace trace, @NotNull JetScope scope, @NotNull DataFlowInfo dataFlowInfo,
             @NotNull ConstructorDescriptor constructorDescriptor,
-            @Nullable JetConstructorDelegationCall call
+            @NotNull JetConstructorDelegationCall call
     ) {
-        // Returns `null` when there is nothing to resolve in trivial cases like `null` call expression or
+        // Method returns `null` when there is nothing to resolve in trivial cases like `null` call expression or
         // when super call should be conventional enum constructor and super call should be empty
-        if (call == null) return null;
 
         BasicCallResolutionContext context = BasicCallResolutionContext.create(
                 trace, scope,

idea/idea-analysis/src/org/jetbrains/kotlin/idea/search/usagesSearch/utils.kt

@@ -157,9 +157,9 @@ private fun processClassDelegationCallsToSpecifiedConstructor(
         klass: JetClass, constructor: DeclarationDescriptor, process: (JetConstructorDelegationCall) -> Unit
 ) {
     for (secondaryConstructor in klass.getSecondaryConstructors()) {
-        val delegationCallDescriptor = secondaryConstructor.getDelegationCall()?.getConstructorCallDescriptor()
+        val delegationCallDescriptor = secondaryConstructor.getDelegationCall().getConstructorCallDescriptor()
         if (constructor == delegationCallDescriptor) {
-            process(secondaryConstructor.getDelegationCall()!!)
+            process(secondaryConstructor.getDelegationCall())
         }
     }
 }