Report errors when iterator() returns a nullable type

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java

@@ -210,11 +210,15 @@ public interface Errors {
     DiagnosticFactory1<JetSimpleNameExpression, ClassifierDescriptor> NO_CLASS_OBJECT = DiagnosticFactory1.create(ERROR);
     SimpleDiagnosticFactory<PsiElement> NO_GENERICS_IN_SUPERTYPE_SPECIFIER = SimpleDiagnosticFactory.create(ERROR);
 
-    SimpleDiagnosticFactory<JetExpression> HAS_NEXT_MISSING = SimpleDiagnosticFactory.create(ERROR);
+    DiagnosticFactory1<JetExpression, JetType> HAS_NEXT_MISSING = DiagnosticFactory1.create(ERROR);
-    SimpleDiagnosticFactory<JetExpression> HAS_NEXT_FUNCTION_AMBIGUITY = SimpleDiagnosticFactory.create(ERROR);
+    DiagnosticFactory1<JetExpression, JetType> HAS_NEXT_FUNCTION_AMBIGUITY = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<JetExpression, JetType> HAS_NEXT_FUNCTION_NONE_APPLICABLE = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<JetExpression, JetType> HAS_NEXT_FUNCTION_TYPE_MISMATCH = DiagnosticFactory1.create(ERROR);
-    SimpleDiagnosticFactory<JetExpression> NEXT_AMBIGUITY = SimpleDiagnosticFactory.create(ERROR);
+
-    SimpleDiagnosticFactory<JetExpression> NEXT_MISSING = SimpleDiagnosticFactory.create(ERROR);
+    DiagnosticFactory1<JetExpression, JetType> NEXT_AMBIGUITY = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<JetExpression, JetType> NEXT_MISSING = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<JetExpression, JetType> NEXT_NONE_APPLICABLE = DiagnosticFactory1.create(ERROR);
+
     SimpleDiagnosticFactory<JetExpression> ITERATOR_MISSING = SimpleDiagnosticFactory.create(ERROR);
     AmbiguousDescriptorDiagnosticFactory ITERATOR_AMBIGUITY = AmbiguousDescriptorDiagnosticFactory.create();
 

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java

@@ -226,12 +226,16 @@ public class DefaultErrorMessages {
         MAP.put(NO_CLASS_OBJECT, "Please specify constructor invocation; classifier ''{0}'' does not have a class object", NAME);
         MAP.put(NO_GENERICS_IN_SUPERTYPE_SPECIFIER, "Generic arguments of the base type must be specified");
 
-        MAP.put(HAS_NEXT_MISSING, "Loop range must have an 'iterator().hasNext()' function or an 'iterator().hasNext' property");
+        MAP.put(HAS_NEXT_MISSING, "hasNext() cannot be called on iterator() of type ''{0}''", RENDER_TYPE);
-        MAP.put(HAS_NEXT_FUNCTION_AMBIGUITY, "Function 'iterator().hasNext()' is ambiguous for this expression");
+        MAP.put(HAS_NEXT_FUNCTION_AMBIGUITY, "hasNext() is ambiguous for iterator() of type ''{0}''", RENDER_TYPE);
+        MAP.put(HAS_NEXT_FUNCTION_NONE_APPLICABLE, "None of the hasNext() functions is applicable for iterator() of type ''{0}''", RENDER_TYPE);
         MAP.put(HAS_NEXT_FUNCTION_TYPE_MISMATCH, "The ''iterator().hasNext()'' function of the loop range must return jet.Boolean, but returns {0}",
                 RENDER_TYPE);
-        MAP.put(NEXT_AMBIGUITY, "Function 'iterator().next()' is ambiguous for this expression");
+
-        MAP.put(NEXT_MISSING, "Loop range must have an 'iterator().next()' function");
+        MAP.put(NEXT_MISSING, "next() cannot be called on iterator() of type ''{0}''", RENDER_TYPE);
+        MAP.put(NEXT_AMBIGUITY, "next() is ambiguous for iterator() of type ''{0}''", RENDER_TYPE);
+        MAP.put(NEXT_NONE_APPLICABLE, "None of the next() functions is applicable for iterator() of type ''{0}''", RENDER_TYPE);
+
         MAP.put(ITERATOR_MISSING, "For-loop range must have an iterator() method");
         MAP.put(ITERATOR_AMBIGUITY, "Method ''iterator()'' is ambiguous for this expression: {0}", AMBIGUOUS_CALLS);
 

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ControlStructureTypingVisitor.java

@@ -25,8 +25,8 @@ import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.descriptors.FunctionDescriptor;
 import org.jetbrains.jet.lang.descriptors.SimpleFunctionDescriptor;
 import org.jetbrains.jet.lang.descriptors.VariableDescriptor;
+import org.jetbrains.jet.lang.diagnostics.DiagnosticFactory1;
 import org.jetbrains.jet.lang.diagnostics.Errors;
-import org.jetbrains.jet.lang.diagnostics.SimpleDiagnosticFactory;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.BindingContextUtils;
@@ -340,12 +340,13 @@ public class ControlStructureTypingVisitor extends ExpressionTypingVisitor {
             FunctionDescriptor iteratorFunction = iteratorResolvedCall.getResultingDescriptor();
             JetType iteratorType = iteratorFunction.getReturnType();
             JetType hasNextType = checkConventionForIterator(context, loopRangeExpression, iteratorType, "hasNext",
-                                                             HAS_NEXT_FUNCTION_AMBIGUITY, HAS_NEXT_MISSING,
+                                                             HAS_NEXT_FUNCTION_AMBIGUITY, HAS_NEXT_MISSING, HAS_NEXT_FUNCTION_NONE_APPLICABLE,
                                                              LOOP_RANGE_HAS_NEXT_RESOLVED_CALL);
             if (hasNextType != null && !isBoolean(hasNextType)) {
                 context.trace.report(HAS_NEXT_FUNCTION_TYPE_MISMATCH.on(loopRangeExpression, hasNextType));
             }
-            return checkConventionForIterator(context, loopRangeExpression, iteratorType, "next", NEXT_AMBIGUITY, NEXT_MISSING,
+            return checkConventionForIterator(context, loopRangeExpression, iteratorType, "next",
+                                              NEXT_AMBIGUITY, NEXT_MISSING, NEXT_NONE_APPLICABLE,
                                               LOOP_RANGE_NEXT_RESOLVED_CALL);
         }
         else {
@@ -370,19 +371,24 @@ public class ControlStructureTypingVisitor extends ExpressionTypingVisitor {
             @NotNull JetExpression loopRangeExpression,
             @NotNull JetType iteratorType,
             @NotNull String name,
-            @NotNull SimpleDiagnosticFactory<JetExpression> ambiguity,
+            @NotNull DiagnosticFactory1<JetExpression, JetType> ambiguity,
-            @NotNull SimpleDiagnosticFactory<JetExpression> missing,
+            @NotNull DiagnosticFactory1<JetExpression, JetType> missing,
+            @NotNull DiagnosticFactory1<JetExpression, JetType> noneApplicable,
             @NotNull WritableSlice<JetExpression, ResolvedCall<FunctionDescriptor>> resolvedCallKey
     ) {
         OverloadResolutionResults<FunctionDescriptor> nextResolutionResults = resolveFakeCall(
                 new TransientReceiver(iteratorType), context, Name.identifier(name));
         if (nextResolutionResults.isAmbiguity()) {
-            context.trace.report(ambiguity.on(loopRangeExpression));
+            context.trace.report(ambiguity.on(loopRangeExpression, iteratorType));
         }
         else if (nextResolutionResults.isNothing()) {
-            context.trace.report(missing.on(loopRangeExpression));
+            context.trace.report(missing.on(loopRangeExpression, iteratorType));
+        }
+        else if (!nextResolutionResults.isSuccess()) {
+            context.trace.report(noneApplicable.on(loopRangeExpression, iteratorType));
         }
         else {
+            assert nextResolutionResults.isSuccess();
             ResolvedCall<FunctionDescriptor> resolvedCall = nextResolutionResults.getResultingCall();
             context.trace.record(resolvedCallKey, loopRangeExpression, resolvedCall);
             return resolvedCall.getResultingDescriptor().getReturnType();

compiler/testData/codegen/controlStructures/forUserType.jet

@@ -66,14 +66,6 @@ fun box() : String {
     System.out?.println(sum)
     if(sum != 10) return "b failed"
 
-    val c7 = MyCollection5()
-    sum = 0
-    for (el in c7) {
-        sum = sum + el!!
-    }
-    if(sum != 0) return "c7 failed"
-
-
     return "OK"
 }
 
@@ -120,14 +112,3 @@ class MyCollection4() {
         fun hasNext() = k > 0
     }
 }
-
-class MyCollection5() {
-    fun iterator() : MyIterator? = null
-
-    class MyIterator() {
-        var k : Int = 5
-
-        fun next() : Int = k--
-        fun hasNext() = k > 0
-    }
-}

compiler/testData/diagnostics/tests/controlStructures/forWithNullableIterator.kt

@@ -0,0 +1,12 @@
+class Coll {
+  fun iterator(): It? = null
+}
+
+class It {
+  fun next() = 1
+  fun hasNext() = false
+}
+
+fun test() {
+  for (x in <!HAS_NEXT_FUNCTION_NONE_APPLICABLE, NEXT_NONE_APPLICABLE!>Coll()<!>) {}
+}

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -15,15 +15,12 @@
  */
 package org.jetbrains.jet.checkers;
 
-import junit.framework.Assert;
 import junit.framework.Test;
 import junit.framework.TestSuite;
-
-import java.io.File;
 import org.jetbrains.jet.JetTestUtils;
 import org.jetbrains.jet.test.TestMetadata;
 
-import org.jetbrains.jet.checkers.AbstractDiagnosticsTestWithEagerResolve;
+import java.io.File;
 
 /** This class is generated by {@link org.jetbrains.jet.checkers.AbstractDiagnosticsTestWithEagerResolve}. DO NOT MODIFY MANUALLY */
 public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEagerResolve {
@@ -879,6 +876,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/controlStructures/forLoopWithNullableRange.kt");
             }
             
+            @TestMetadata("forWithNullableIterator.kt")
+            public void testForWithNullableIterator() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/controlStructures/forWithNullableIterator.kt");
+            }
+            
             @TestMetadata("ForWithoutBraces.kt")
             public void testForWithoutBraces() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/controlStructures/ForWithoutBraces.kt");

compiler/tests/org/jetbrains/jet/codegen/ClassGenTest.java

@@ -312,7 +312,7 @@ public class ClassGenTest extends CodegenTestCase {
     }
 
     public void testKt903() throws Exception {
-        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_AND_ANNOTATIONS);
         blackBoxFile("regressions/kt903.jet");
     }
 
@@ -403,7 +403,7 @@ public class ClassGenTest extends CodegenTestCase {
     }
 
     public void testKt1980() {
-        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_AND_ANNOTATIONS);
         blackBoxFile("regressions/kt1980.kt");
     }
 

compiler/tests/org/jetbrains/jet/codegen/ControlStructuresTest.java

@@ -108,7 +108,7 @@ public class ControlStructuresTest extends CodegenTestCase {
     }
 
     public void testFor() throws Exception {
-        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_AND_ANNOTATIONS);
         loadFile();
 //        System.out.println(generateToText());
         final Method main = generateFunction();
@@ -117,7 +117,7 @@ public class ControlStructuresTest extends CodegenTestCase {
     }
 
     public void testIfBlock() throws Exception {
-        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_AND_ANNOTATIONS);
         loadFile();
 //        System.out.println(generateToText());
         final Method main = generateFunction();

compiler/tests/org/jetbrains/jet/codegen/SafeRefTest.java

@@ -22,7 +22,7 @@ public class SafeRefTest extends CodegenTestCase {
     @Override
     protected void setUp() throws Exception {
         super.setUp();
-        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
+        createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_AND_ANNOTATIONS);
     }
 
     public void test247 () throws Exception {

idea/tests/org/jetbrains/jet/plugin/codeInsight/LiveTemplatesTest.java

@@ -165,7 +165,7 @@ public class LiveTemplatesTest extends LightCodeInsightFixtureTestCase {
     public void testIter() {
         start();
 
-        assertStringItems("args", "collection", "myList", "str", "stream");
+        assertStringItems("args", "myList", "str", "stream");
         type("args");
         nextTab(2);
 

libraries/stdlib/src/kotlin/test/TestJVM.kt

@@ -17,7 +17,7 @@ public var asserter: Asserter
         if (_asserter == null) {
             val klass = javaClass<Asserter>()
             val loader = ServiceLoader.load(klass)!!
-            for (a in loader) {
+            for (a in loader.iterator()!!) {
                 if (a != null) {
                     _asserter = a
                     break