diff --git a/compiler/frontend/src/org/jetbrains/jet/checkers/CheckerTestUtil.java b/compiler/frontend/src/org/jetbrains/jet/checkers/CheckerTestUtil.java
index c364fa0b31f..79db9004292 100644
--- a/compiler/frontend/src/org/jetbrains/jet/checkers/CheckerTestUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/checkers/CheckerTestUtil.java
@@ -347,16 +347,16 @@ public class CheckerTestUtil {
 
     public static class AbstractDiagnosticForTests implements Diagnostic {
         private final PsiElement element;
-        private final DiagnosticFactory factory;
+        private final DiagnosticFactory<?> factory;
 
-        public AbstractDiagnosticForTests(@NotNull PsiElement element, @NotNull DiagnosticFactory factory) {
+        public AbstractDiagnosticForTests(@NotNull PsiElement element, @NotNull DiagnosticFactory<?> factory) {
             this.element = element;
             this.factory = factory;
         }
 
         @NotNull
         @Override
-        public DiagnosticFactory getFactory() {
+        public DiagnosticFactory<?> getFactory() {
             return factory;
         }
 
@@ -390,7 +390,7 @@ public class CheckerTestUtil {
         }
     }
 
-    public static class SyntaxErrorDiagnosticFactory extends DiagnosticFactory {
+    public static class SyntaxErrorDiagnosticFactory extends DiagnosticFactory<SyntaxErrorDiagnostic> {
         public static final SyntaxErrorDiagnosticFactory INSTANCE = new SyntaxErrorDiagnosticFactory();
 
         private SyntaxErrorDiagnosticFactory() {
@@ -410,7 +410,7 @@ public class CheckerTestUtil {
         }
     }
 
-    public static class DebugInfoDiagnosticFactory extends DiagnosticFactory {
+    public static class DebugInfoDiagnosticFactory extends DiagnosticFactory<DebugInfoDiagnostic> {
         public static final DebugInfoDiagnosticFactory AUTOCAST = new DebugInfoDiagnosticFactory("AUTOCAST");
         public static final DebugInfoDiagnosticFactory ELEMENT_WITH_ERROR_TYPE = new DebugInfoDiagnosticFactory("ELEMENT_WITH_ERROR_TYPE");
         public static final DebugInfoDiagnosticFactory UNRESOLVED_WITH_TARGET = new DebugInfoDiagnosticFactory("UNRESOLVED_WITH_TARGET");
diff --git a/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java b/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java
index a8d8130474a..33f23929efe 100644
--- a/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java
@@ -58,9 +58,9 @@ public class DebugInfoUtil {
             @NotNull final BindingContext bindingContext,
             @NotNull final DebugInfoReporter debugInfoReporter
     ) {
-        final Map<JetReferenceExpression, DiagnosticFactory> markedWithErrorElements = Maps.newHashMap();
+        final Map<JetReferenceExpression, DiagnosticFactory<?>> markedWithErrorElements = Maps.newHashMap();
         for (Diagnostic diagnostic : bindingContext.getDiagnostics()) {
-            DiagnosticFactory factory = diagnostic.getFactory();
+            DiagnosticFactory<?> factory = diagnostic.getFactory();
             if (Errors.UNRESOLVED_REFERENCE_DIAGNOSTICS.contains(diagnostic.getFactory())) {
                 markedWithErrorElements.put((JetReferenceExpression) diagnostic.getPsiElement(), factory);
             }
@@ -136,7 +136,7 @@ public class DebugInfoUtil {
                     markedWithError = true;
                 }
                 JetType expressionType = bindingContext.get(EXPRESSION_TYPE, expression);
-                DiagnosticFactory factory = markedWithErrorElements.get(expression);
+                DiagnosticFactory<?> factory = markedWithErrorElements.get(expression);
                 if (declarationDescriptor != null &&
                     (ErrorUtils.isError(declarationDescriptor) || ErrorUtils.containsErrorType(expressionType))) {
                     if (factory != Errors.EXPRESSION_EXPECTED_PACKAGE_FOUND) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
index da081a8eea6..ee2d8520e63 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
@@ -274,7 +274,7 @@ public class JetFlowInformationProvider {
         final Set<VariableDescriptor> declaredVariables = pseudocodeVariablesData.getDeclaredVariables(pseudocode, true);
         final LexicalScopeVariableInfo lexicalScopeVariableInfo = pseudocodeVariablesData.getLexicalScopeVariableInfo();
 
-        final Map<Instruction, DiagnosticFactory> reportedDiagnosticMap = Maps.newHashMap();
+        final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
 
         PseudocodeTraverserPackage.traverse(
                 pseudocode, FORWARD, initializers,
@@ -548,7 +548,7 @@ public class JetFlowInformationProvider {
         final PseudocodeVariablesData pseudocodeVariablesData = getPseudocodeVariablesData();
         Map<Instruction, Edges<Map<VariableDescriptor, VariableUseState>>> variableStatusData =
                 pseudocodeVariablesData.getVariableUseStatusData();
-        final Map<Instruction, DiagnosticFactory> reportedDiagnosticMap = Maps.newHashMap();
+        final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
         InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>> variableStatusAnalyzeStrategy =
                 new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>>() {
                     @Override
@@ -638,7 +638,7 @@ public class JetFlowInformationProvider {
 //  "Unused literals" in block
 
     public void markUnusedLiteralsInBlock() {
-        final Map<Instruction, DiagnosticFactory> reportedDiagnosticMap = Maps.newHashMap();
+        final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap = Maps.newHashMap();
         PseudocodeTraverserPackage.traverse(
                 pseudocode, FORWARD, new FunctionVoid1<Instruction>() {
                     @Override
@@ -828,13 +828,13 @@ public class JetFlowInformationProvider {
             trace.report(diagnostic);
             return;
         }
-        Map<Instruction, DiagnosticFactory> previouslyReported = ctxt.reportedDiagnosticMap;
+        Map<Instruction, DiagnosticFactory<?>> previouslyReported = ctxt.reportedDiagnosticMap;
         previouslyReported.put(instruction, diagnostic.getFactory());
 
         boolean alreadyReported = false;
         boolean sameErrorForAllCopies = true;
         for (Instruction copy : instruction.getCopies()) {
-            DiagnosticFactory previouslyReportedErrorFactory = previouslyReported.get(copy);
+            DiagnosticFactory<?> previouslyReportedErrorFactory = previouslyReported.get(copy);
             if (previouslyReportedErrorFactory != null) {
                 alreadyReported = true;
             }
@@ -857,7 +857,7 @@ public class JetFlowInformationProvider {
         }
     }
 
-    private static boolean mustBeReportedOnAllCopies(@NotNull DiagnosticFactory diagnosticFactory) {
+    private static boolean mustBeReportedOnAllCopies(@NotNull DiagnosticFactory<?> diagnosticFactory) {
         return diagnosticFactory == UNUSED_VARIABLE
                || diagnosticFactory == UNUSED_PARAMETER
                || diagnosticFactory == UNUSED_CHANGED_VALUE;
@@ -865,13 +865,13 @@ public class JetFlowInformationProvider {
 
 
     private class VariableContext {
-        final Map<Instruction, DiagnosticFactory> reportedDiagnosticMap;
+        final Map<Instruction, DiagnosticFactory<?>> reportedDiagnosticMap;
         final Instruction instruction;
         final VariableDescriptor variableDescriptor;
 
         private VariableContext(
                 @NotNull Instruction instruction,
-                @NotNull Map<Instruction, DiagnosticFactory> map
+                @NotNull Map<Instruction, DiagnosticFactory<?>> map
         ) {
             this.instruction = instruction;
             reportedDiagnosticMap = map;
@@ -885,7 +885,7 @@ public class JetFlowInformationProvider {
 
         private VariableInitContext(
                 @NotNull Instruction instruction,
-                @NotNull Map<Instruction, DiagnosticFactory> map,
+                @NotNull Map<Instruction, DiagnosticFactory<?>> map,
                 @NotNull Map<VariableDescriptor, VariableInitState> in,
                 @NotNull Map<VariableDescriptor, VariableInitState> out,
                 @NotNull LexicalScopeVariableInfo lexicalScopeVariableInfo
@@ -914,7 +914,7 @@ public class JetFlowInformationProvider {
 
         private VariableUseContext(
                 @NotNull Instruction instruction,
-                @NotNull Map<Instruction, DiagnosticFactory> map,
+                @NotNull Map<Instruction, DiagnosticFactory<?>> map,
                 @NotNull Map<VariableDescriptor, VariableUseState> in,
                 @NotNull Map<VariableDescriptor, VariableUseState> out
         ) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/AbstractDiagnostic.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/AbstractDiagnostic.java
index 698c71c13ee..598049b6c5a 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/AbstractDiagnostic.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/AbstractDiagnostic.java
@@ -18,20 +18,18 @@ package org.jetbrains.jet.lang.diagnostics;
 
 import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiErrorElement;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.JetNodeTypes;
 
 import java.util.List;
 
 public abstract class AbstractDiagnostic<E extends PsiElement> implements ParametrizedDiagnostic<E> {
     private final E psiElement;
-    private final DiagnosticFactoryWithPsiElement<E> factory;
+    private final DiagnosticFactoryWithPsiElement<E, ?> factory;
     private final Severity severity;
 
     public AbstractDiagnostic(@NotNull E psiElement,
-            @NotNull DiagnosticFactoryWithPsiElement<E> factory,
+            @NotNull DiagnosticFactoryWithPsiElement<E, ?> factory,
             @NotNull Severity severity) {
         this.psiElement = psiElement;
         this.factory = factory;
@@ -40,7 +38,7 @@ public abstract class AbstractDiagnostic<E extends PsiElement> implements Parame
 
     @NotNull
     @Override
-    public DiagnosticFactoryWithPsiElement<E> getFactory() {
+    public DiagnosticFactoryWithPsiElement<E, ?> getFactory() {
         return factory;
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Diagnostic.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Diagnostic.java
index 289ab29be31..36e67fc6db4 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Diagnostic.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Diagnostic.java
@@ -26,7 +26,7 @@ import java.util.List;
 public interface Diagnostic {
 
     @NotNull
-    DiagnosticFactory getFactory();
+    DiagnosticFactory<?> getFactory();
 
     @NotNull
     Severity getSeverity();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory.java
index 07e41d0b8d9..df69c1ac27c 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory.java
@@ -18,7 +18,10 @@ package org.jetbrains.jet.lang.diagnostics;
 
 import org.jetbrains.annotations.NotNull;
 
-public abstract class DiagnosticFactory {
+import java.util.Arrays;
+import java.util.Collection;
+
+public abstract class DiagnosticFactory<D extends Diagnostic> {
 
     private String name = null;
     private final Severity severity;
@@ -41,6 +44,30 @@ public abstract class DiagnosticFactory {
         return severity;
     }
 
+    @NotNull
+    public D cast(@NotNull Diagnostic diagnostic) {
+        if (diagnostic.getFactory() != this) {
+            throw new IllegalArgumentException("Factory mismatch: expected " + this + " but was " + diagnostic.getFactory());
+        }
+
+        //noinspection unchecked
+        return (D) diagnostic;
+    }
+
+    @NotNull
+    public static <D extends Diagnostic> D cast(@NotNull Diagnostic diagnostic, @NotNull DiagnosticFactory<? extends D>... factories) {
+        return cast(diagnostic, Arrays.asList(factories));
+    }
+
+    @NotNull
+    public static <D extends Diagnostic> D cast(@NotNull Diagnostic diagnostic, @NotNull Collection<? extends DiagnosticFactory<? extends D>> factories) {
+        for (DiagnosticFactory<? extends D> factory : factories) {
+            if (diagnostic.getFactory() == factory) return factory.cast(diagnostic);
+        }
+
+        throw new IllegalArgumentException("Factory mismatch: expected one of " + factories + " but was " + diagnostic.getFactory());
+    }
+
     @Override
     public String toString() {
         return getName();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory0.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory0.java
index dcddb16857e..d1c6e8dffbc 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory0.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory0.java
@@ -19,7 +19,7 @@ package org.jetbrains.jet.lang.diagnostics;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 
-public class DiagnosticFactory0<E extends PsiElement> extends DiagnosticFactoryWithPsiElement<E> {
+public class DiagnosticFactory0<E extends PsiElement> extends DiagnosticFactoryWithPsiElement<E, SimpleDiagnostic<E>> {
 
     protected DiagnosticFactory0(Severity severity, PositioningStrategy<? super E> positioningStrategy) {
         super(severity, positioningStrategy);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory1.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory1.java
index f1dbd821742..7ba9e19a818 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory1.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory1.java
@@ -19,7 +19,7 @@ package org.jetbrains.jet.lang.diagnostics;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 
-public class DiagnosticFactory1<E extends PsiElement, A> extends DiagnosticFactoryWithPsiElement<E> {
+public class DiagnosticFactory1<E extends PsiElement, A> extends DiagnosticFactoryWithPsiElement<E, DiagnosticWithParameters1<E, A>> {
     @NotNull
     public ParametrizedDiagnostic<E> on(@NotNull E element, @NotNull A argument) {
         return new DiagnosticWithParameters1<E, A>(element, argument, this, getSeverity());
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory2.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory2.java
index bb0496ec2c8..064d9d8fca8 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory2.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory2.java
@@ -19,7 +19,7 @@ package org.jetbrains.jet.lang.diagnostics;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 
-public class DiagnosticFactory2<E extends PsiElement, A, B> extends DiagnosticFactoryWithPsiElement<E> {
+public class DiagnosticFactory2<E extends PsiElement, A, B> extends DiagnosticFactoryWithPsiElement<E, DiagnosticWithParameters2<E, A, B>> {
 
     @NotNull
     public ParametrizedDiagnostic<E> on(@NotNull E element, @NotNull A a, @NotNull B b) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory3.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory3.java
index a53027f54a1..d6ec01d7507 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory3.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactory3.java
@@ -19,7 +19,7 @@ package org.jetbrains.jet.lang.diagnostics;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 
-public class DiagnosticFactory3<E extends PsiElement, A, B, C> extends DiagnosticFactoryWithPsiElement<E> {
+public class DiagnosticFactory3<E extends PsiElement, A, B, C> extends DiagnosticFactoryWithPsiElement<E, DiagnosticWithParameters3<E, A, B, C>> {
 
     protected DiagnosticFactory3(Severity severity, PositioningStrategy<? super E> positioningStrategy) {
         super(severity, positioningStrategy);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactoryWithPsiElement.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactoryWithPsiElement.java
index e35731c9c1b..5a01175740d 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactoryWithPsiElement.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/DiagnosticFactoryWithPsiElement.java
@@ -21,7 +21,7 @@ import com.intellij.psi.PsiElement;
 
 import java.util.List;
 
-public abstract class DiagnosticFactoryWithPsiElement<E extends PsiElement> extends DiagnosticFactory {
+public abstract class DiagnosticFactoryWithPsiElement<E extends PsiElement, D extends Diagnostic> extends DiagnosticFactory<D> {
     protected final PositioningStrategy<? super E> positioningStrategy;
 
     public DiagnosticFactoryWithPsiElement(Severity severity, PositioningStrategy<? super E> positioningStrategy) {
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java
index a54b07d2b52..7b3d1008aa8 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java
@@ -589,11 +589,11 @@ public interface Errors {
     DiagnosticFactory0<JetElement> DECLARATION_CANT_BE_INLINED = DiagnosticFactory0.create(ERROR);
 
     // Error sets
-    ImmutableSet<? extends DiagnosticFactory> UNRESOLVED_REFERENCE_DIAGNOSTICS = ImmutableSet.of(
+    ImmutableSet<? extends DiagnosticFactory<?>> UNRESOLVED_REFERENCE_DIAGNOSTICS = ImmutableSet.of(
             UNRESOLVED_REFERENCE, NAMED_PARAMETER_NOT_FOUND, UNRESOLVED_REFERENCE_WRONG_RECEIVER);
-    ImmutableSet<? extends DiagnosticFactory> UNUSED_ELEMENT_DIAGNOSTICS = ImmutableSet.of(
+    ImmutableSet<? extends DiagnosticFactory<?>> UNUSED_ELEMENT_DIAGNOSTICS = ImmutableSet.of(
             UNUSED_VARIABLE, UNUSED_PARAMETER, ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE);
-    ImmutableSet<? extends DiagnosticFactory> TYPE_INFERENCE_ERRORS = ImmutableSet.of(
+    ImmutableSet<? extends DiagnosticFactory<?>> TYPE_INFERENCE_ERRORS = ImmutableSet.of(
             TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER, TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS, TYPE_INFERENCE_TYPE_CONSTRUCTOR_MISMATCH,
             TYPE_INFERENCE_UPPER_BOUND_VIOLATED, TYPE_INFERENCE_EXPECTED_TYPE_MISMATCH);
 
@@ -612,7 +612,7 @@ public interface Errors {
                     try {
                         Object value = field.get(null);
                         if (value instanceof DiagnosticFactory) {
-                            DiagnosticFactory factory = (DiagnosticFactory)value;
+                            DiagnosticFactory<?> factory = (DiagnosticFactory<?>)value;
                             factory.setName(field.getName());
                         }
                     }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java
index 027c19ed869..5a81a687f86 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java
@@ -493,8 +493,8 @@ public class DefaultErrorMessages {
                 try {
                     Object fieldValue = field.get(null);
                     if (fieldValue instanceof DiagnosticFactory) {
-                        if (MAP.get((DiagnosticFactory) fieldValue) == null) {
-                            throw new IllegalStateException("No default diagnostic renderer is provided for " + ((DiagnosticFactory)fieldValue).getName());
+                        if (MAP.get((DiagnosticFactory<?>) fieldValue) == null) {
+                            throw new IllegalStateException("No default diagnostic renderer is provided for " + ((DiagnosticFactory<?>)fieldValue).getName());
                         }
                     }
                 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DiagnosticFactoryToRendererMap.java b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DiagnosticFactoryToRendererMap.java
index 35bb44dcd3f..96bdeb669cb 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DiagnosticFactoryToRendererMap.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DiagnosticFactoryToRendererMap.java
@@ -26,8 +26,8 @@ import java.util.HashMap;
 import java.util.Map;
 
 public final class DiagnosticFactoryToRendererMap {
-    private final Map<DiagnosticFactory, DiagnosticRenderer<?>> map =
-            new HashMap<DiagnosticFactory, DiagnosticRenderer<?>>();
+    private final Map<DiagnosticFactory<?>, DiagnosticRenderer<?>> map =
+            new HashMap<DiagnosticFactory<?>, DiagnosticRenderer<?>>();
     private boolean immutable = false;
 
     private void checkMutability() {
@@ -64,7 +64,7 @@ public final class DiagnosticFactoryToRendererMap {
     }
 
     @Nullable
-    public DiagnosticRenderer<?> get(@NotNull DiagnosticFactory factory) {
+    public DiagnosticRenderer<?> get(@NotNull DiagnosticFactory<?> factory) {
         return map.get(factory);
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DiagnosticsWithSuppression.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DiagnosticsWithSuppression.java
index 8cfaf7ca55f..275751bbf0a 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DiagnosticsWithSuppression.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DiagnosticsWithSuppression.java
@@ -111,7 +111,7 @@ public class DiagnosticsWithSuppression implements Diagnostics {
     private static boolean isSuppressedForDebugger(@NotNull Diagnostic diagnostic, @NotNull PsiElement element) {
         PsiFile containingFile = element.getContainingFile();
         if (containingFile instanceof JetFile && CodeFragmentUtilPackage.skipVisibilityCheck((JetFile) containingFile)) {
-            DiagnosticFactory diagnosticFactory = diagnostic.getFactory();
+            DiagnosticFactory<?> diagnosticFactory = diagnostic.getFactory();
             return diagnosticFactory == Errors.INVISIBLE_MEMBER ||
                    diagnosticFactory == Errors.INVISIBLE_REFERENCE ||
                    diagnosticFactory == Errors.INVISIBLE_SETTER;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/constants/CompileTimeConstantChecker.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/constants/CompileTimeConstantChecker.java
index 285fb4b5f83..ade5431b98a 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/constants/CompileTimeConstantChecker.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/constants/CompileTimeConstantChecker.java
@@ -36,8 +36,8 @@ import java.util.Set;
 import static org.jetbrains.jet.lang.diagnostics.Errors.*;
 
 public class CompileTimeConstantChecker {
-    private static final Set<DiagnosticFactory> errorsThatDependOnExpectedType =
-            Sets.<DiagnosticFactory>newHashSet(CONSTANT_EXPECTED_TYPE_MISMATCH, NULL_FOR_NONNULL_TYPE);
+    private static final Set<DiagnosticFactory<?>> errorsThatDependOnExpectedType =
+            Sets.<DiagnosticFactory<?>>newHashSet(CONSTANT_EXPECTED_TYPE_MISMATCH, NULL_FOR_NONNULL_TYPE);
 
     private final KotlinBuiltIns builtIns;
     private final BindingTrace trace;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java
index 5a8715597e4..852453f93cb 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java
@@ -451,7 +451,7 @@ public class ExpressionTypingUtils {
 
             @Override
             public void report(@NotNull Diagnostic diagnostic) {
-                DiagnosticFactory factory = diagnostic.getFactory();
+                DiagnosticFactory<?> factory = diagnostic.getFactory();
                 if ((factory == TYPE_MISMATCH || factory == CONSTANT_EXPECTED_TYPE_MISMATCH || factory == NULL_FOR_NONNULL_TYPE)
                         && diagnostic.getPsiElement() == expressionToWatch) {
                     mismatchFound[0] = true;
diff --git a/compiler/tests/org/jetbrains/jet/checkers/AbstractJetDiagnosticsTest.java b/compiler/tests/org/jetbrains/jet/checkers/AbstractJetDiagnosticsTest.java
index 117676f9ea5..aa15466ae41 100644
--- a/compiler/tests/org/jetbrains/jet/checkers/AbstractJetDiagnosticsTest.java
+++ b/compiler/tests/org/jetbrains/jet/checkers/AbstractJetDiagnosticsTest.java
@@ -31,6 +31,7 @@ import org.jetbrains.jet.lang.descriptors.DependencyKind;
 import org.jetbrains.jet.lang.descriptors.ModuleDescriptorImpl;
 import org.jetbrains.jet.lang.diagnostics.*;
 import org.jetbrains.jet.lang.psi.JetElement;
+import org.jetbrains.jet.lang.psi.JetExpression;
 import org.jetbrains.jet.lang.psi.JetFile;
 import org.jetbrains.jet.lang.resolve.AnalyzingUtils;
 import org.jetbrains.jet.lang.resolve.BindingContext;
@@ -146,23 +147,26 @@ public abstract class AbstractJetDiagnosticsTest extends BaseDiagnosticsTest {
 
     @SuppressWarnings({"unchecked", "ConstantConditions"})
     private static void checkResolvedCallsInDiagnostics(BindingContext bindingContext) {
-        Set<DiagnosticFactory> diagnosticsStoringResolvedCalls1 = Sets.<DiagnosticFactory>newHashSet(
+        Set<DiagnosticFactory1<PsiElement, Collection<? extends ResolvedCall<?>>>> diagnosticsStoringResolvedCalls1 = Sets.newHashSet(
                 OVERLOAD_RESOLUTION_AMBIGUITY, NONE_APPLICABLE, CANNOT_COMPLETE_RESOLVE, UNRESOLVED_REFERENCE_WRONG_RECEIVER,
                 ASSIGN_OPERATOR_AMBIGUITY, ITERATOR_AMBIGUITY);
-        Set<DiagnosticFactory> diagnosticsStoringResolvedCalls2 = Sets.<DiagnosticFactory>newHashSet(
+        Set<DiagnosticFactory2<JetExpression, ? extends Comparable<? extends Comparable<?>>, Collection<? extends ResolvedCall<?>>>>
+                diagnosticsStoringResolvedCalls2 = Sets.newHashSet(
                 COMPONENT_FUNCTION_AMBIGUITY, DELEGATE_SPECIAL_FUNCTION_AMBIGUITY, DELEGATE_SPECIAL_FUNCTION_NONE_APPLICABLE);
         Diagnostics diagnostics = bindingContext.getDiagnostics();
         for (Diagnostic diagnostic : diagnostics) {
-            DiagnosticFactory factory = diagnostic.getFactory();
+            DiagnosticFactory<?> factory = diagnostic.getFactory();
+            //noinspection SuspiciousMethodCalls
             if (diagnosticsStoringResolvedCalls1.contains(factory)) {
                 assertResolvedCallsAreCompleted(
-                        diagnostic, ((DiagnosticWithParameters1<PsiElement, Collection<? extends ResolvedCall<?>>>) diagnostic).getA());
+                        diagnostic, DiagnosticFactory.cast(diagnostic, diagnosticsStoringResolvedCalls1).getA());
 
             }
+            //noinspection SuspiciousMethodCalls
             if (diagnosticsStoringResolvedCalls2.contains(factory)) {
                 assertResolvedCallsAreCompleted(
                         diagnostic,
-                        ((DiagnosticWithParameters2<PsiElement, Object, Collection<? extends ResolvedCall<?>>>)diagnostic).getB());
+                        DiagnosticFactory.cast(diagnostic, diagnosticsStoringResolvedCalls2).getB());
             }
         }
     }
diff --git a/compiler/tests/org/jetbrains/jet/checkers/BaseDiagnosticsTest.java b/compiler/tests/org/jetbrains/jet/checkers/BaseDiagnosticsTest.java
index c23d380a4cf..00092caf066 100644
--- a/compiler/tests/org/jetbrains/jet/checkers/BaseDiagnosticsTest.java
+++ b/compiler/tests/org/jetbrains/jet/checkers/BaseDiagnosticsTest.java
@@ -55,7 +55,7 @@ public abstract class BaseDiagnosticsTest extends JetLiteFixture {
 
     public static final String DIAGNOSTICS_DIRECTIVE = "DIAGNOSTICS";
     public static final Pattern DIAGNOSTICS_PATTERN = Pattern.compile("([\\+\\-!])(\\w+)\\s*");
-    public static final ImmutableSet<DiagnosticFactory> DIAGNOSTICS_TO_INCLUDE_ANYWAY =
+    public static final ImmutableSet<DiagnosticFactory<?>> DIAGNOSTICS_TO_INCLUDE_ANYWAY =
             ImmutableSet.of(
                     Errors.UNRESOLVED_REFERENCE,
                     Errors.UNRESOLVED_REFERENCE_WRONG_RECEIVER,
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/KotlinSuppressableWarningProblemGroup.kt b/idea/src/org/jetbrains/jet/plugin/highlighter/KotlinSuppressableWarningProblemGroup.kt
index fc7b57c15b3..5ff1a7bcf07 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/KotlinSuppressableWarningProblemGroup.kt
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/KotlinSuppressableWarningProblemGroup.kt
@@ -28,7 +28,7 @@ import org.jetbrains.jet.lang.diagnostics.DiagnosticFactory
 import com.intellij.psi.util.PsiTreeUtil
 
 class KotlinSuppressableWarningProblemGroup(
-        private val diagnosticFactory: DiagnosticFactory
+        private val diagnosticFactory: DiagnosticFactory<*>
 ) : SuppressableProblemGroup {
 
     {
@@ -46,7 +46,7 @@ class KotlinSuppressableWarningProblemGroup(
 
 }
 
-fun createSuppressWarningActions(element: PsiElement, diagnosticFactory: DiagnosticFactory): List<SuppressIntentionAction> {
+fun createSuppressWarningActions(element: PsiElement, diagnosticFactory: DiagnosticFactory<*>): List<SuppressIntentionAction> {
     if (diagnosticFactory.getSeverity() != Severity.WARNING)
         return Collections.emptyList()
 
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/AddStarProjectionsFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/AddStarProjectionsFix.java
index f271ef8bf12..4585242a8ed 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/AddStarProjectionsFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/AddStarProjectionsFix.java
@@ -72,10 +72,8 @@ public abstract class AddStarProjectionsFix extends JetIntentionAction<JetUserTy
         return new JetSingleIntentionActionFactory() {
             @Override
             public IntentionAction createAction(Diagnostic diagnostic) {
-                assert diagnostic.getFactory() == Errors.NO_TYPE_ARGUMENTS_ON_RHS;
-                @SuppressWarnings("unchecked")
                 DiagnosticWithParameters2<JetTypeReference, Integer, String> diagnosticWithParameters =
-                        (DiagnosticWithParameters2<JetTypeReference, Integer, String>) diagnostic;
+                        Errors.NO_TYPE_ARGUMENTS_ON_RHS.cast(diagnostic);
                 JetTypeElement typeElement = diagnosticWithParameters.getPsiElement().getTypeElement();
                 while (typeElement instanceof JetNullableType) {
                     typeElement = ((JetNullableType) typeElement).getInnerType();
@@ -91,9 +89,7 @@ public abstract class AddStarProjectionsFix extends JetIntentionAction<JetUserTy
         return new JetSingleIntentionActionFactory() {
             @Override
             public IntentionAction createAction(Diagnostic diagnostic) {
-                assert diagnostic.getFactory() == Errors.WRONG_NUMBER_OF_TYPE_ARGUMENTS;
-                @SuppressWarnings("unchecked")
-                DiagnosticWithParameters1<JetElement, Integer> diagnosticWithParameters = (DiagnosticWithParameters1) diagnostic;
+                DiagnosticWithParameters1<JetElement, Integer> diagnosticWithParameters = Errors.WRONG_NUMBER_OF_TYPE_ARGUMENTS.cast(diagnostic);
 
                 Integer size = diagnosticWithParameters.getA();
 
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/CastExpressionFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/CastExpressionFix.java
index ed76f015423..4390f5eff4f 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/CastExpressionFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/CastExpressionFix.java
@@ -86,10 +86,8 @@ public class CastExpressionFix extends JetIntentionAction<JetExpression> {
             @Nullable
             @Override
             public IntentionAction createAction(Diagnostic diagnostic) {
-                assert diagnostic.getFactory() == Errors.AUTOCAST_IMPOSSIBLE;
-                @SuppressWarnings("unchecked")
                 DiagnosticWithParameters2<JetExpression, JetType, String> diagnosticWithParameters =
-                        (DiagnosticWithParameters2<JetExpression, JetType, String>) diagnostic;
+                        Errors.AUTOCAST_IMPOSSIBLE.cast(diagnostic);
                 return new CastExpressionFix(diagnosticWithParameters.getPsiElement(), diagnosticWithParameters.getA());
             }
         };
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionReturnTypeFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionReturnTypeFix.java
index 0c943ad4a73..37a1288dc19 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionReturnTypeFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionReturnTypeFix.java
@@ -29,14 +29,12 @@ import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.FunctionDescriptor;
 import org.jetbrains.jet.lang.descriptors.SimpleFunctionDescriptor;
 import org.jetbrains.jet.lang.diagnostics.Diagnostic;
-import org.jetbrains.jet.lang.diagnostics.DiagnosticWithParameters3;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.BindingContextUtils;
 import org.jetbrains.jet.lang.resolve.DescriptorResolver;
 import org.jetbrains.jet.lang.resolve.calls.model.ResolvedCall;
 import org.jetbrains.jet.lang.resolve.name.FqName;
-import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.types.ErrorUtils;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.checker.JetTypeChecker;
@@ -49,6 +47,8 @@ import org.jetbrains.jet.renderer.DescriptorRenderer;
 import java.util.LinkedList;
 import java.util.List;
 
+import static org.jetbrains.jet.lang.diagnostics.Errors.COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH;
+
 public class ChangeFunctionReturnTypeFix extends JetIntentionAction<JetFunction> {
     private final JetType type;
     private final String renderedType;
@@ -127,8 +127,7 @@ public class ChangeFunctionReturnTypeFix extends JetIntentionAction<JetFunction>
 
     @NotNull
     public static JetMultiDeclarationEntry getMultiDeclarationEntryThatTypeMismatchComponentFunction(Diagnostic diagnostic) {
-        @SuppressWarnings("unchecked")
-        String componentName = ((DiagnosticWithParameters3<JetExpression, Name, JetType, JetType>) diagnostic).getA().asString();
+        String componentName = COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH.cast(diagnostic).getA().asString();
         int componentIndex = Integer.valueOf(componentName.substring(DescriptorResolver.COMPONENT_FUNCTION_NAME_PREFIX.length()));
         JetMultiDeclaration multiDeclaration = QuickFixUtil.getParentElementOfType(diagnostic, JetMultiDeclaration.class);
         assert multiDeclaration != null : "COMPONENT_FUNCTION_RETURN_TYPE_MISMATCH reported on expression that is not within any multi declaration";
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionSignatureFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionSignatureFix.java
index 5f0e610ed8f..f5094022b7d 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionSignatureFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeFunctionSignatureFix.java
@@ -20,7 +20,6 @@ import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.project.Project;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
-import com.intellij.psi.PsiNameIdentifierOwner;
 import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -29,8 +28,9 @@ import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.descriptors.FunctionDescriptor;
 import org.jetbrains.jet.lang.descriptors.ValueParameterDescriptor;
 import org.jetbrains.jet.lang.diagnostics.Diagnostic;
-import org.jetbrains.jet.lang.diagnostics.DiagnosticWithParameters1;
+import org.jetbrains.jet.lang.diagnostics.DiagnosticFactory;
 import org.jetbrains.jet.lang.diagnostics.DiagnosticWithParameters2;
+import org.jetbrains.jet.lang.diagnostics.Errors;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.BindingContextUtils;
@@ -46,6 +46,8 @@ import org.jetbrains.jet.plugin.refactoring.changeSignature.JetParameterInfo;
 import java.util.List;
 
 import static org.jetbrains.jet.lang.descriptors.CallableMemberDescriptor.Kind.SYNTHESIZED;
+import static org.jetbrains.jet.lang.diagnostics.Errors.EXPECTED_PARAMETERS_NUMBER_MISMATCH;
+import static org.jetbrains.jet.lang.diagnostics.Errors.UNUSED_PARAMETER;
 
 public abstract class ChangeFunctionSignatureFix extends JetIntentionAction<PsiElement> {
     protected final PsiElement context;
@@ -143,8 +145,8 @@ public abstract class ChangeFunctionSignatureFix extends JetIntentionAction<PsiE
             @Override
             public ChangeFunctionSignatureFix createAction(Diagnostic diagnostic) {
                 JetCallElement callElement = PsiTreeUtil.getParentOfType(diagnostic.getPsiElement(), JetCallElement.class);
-                @SuppressWarnings("unchecked")
-                CallableDescriptor descriptor = ((DiagnosticWithParameters1<PsiElement, CallableDescriptor>) diagnostic).getA();
+                //noinspection unchecked
+                CallableDescriptor descriptor = DiagnosticFactory.cast(diagnostic, Errors.TOO_MANY_ARGUMENTS, Errors.NO_VALUE_FOR_PARAMETER).getA();
 
                 if (callElement != null) {
                     return createFix(callElement, callElement, descriptor);
@@ -159,9 +161,8 @@ public abstract class ChangeFunctionSignatureFix extends JetIntentionAction<PsiE
         return new JetSingleIntentionActionFactory() {
             @Override
             public ChangeFunctionSignatureFix createAction(Diagnostic diagnostic) {
-                @SuppressWarnings("unchecked")
                 DiagnosticWithParameters2<JetFunctionLiteral, Integer, List<JetType>> diagnosticWithParameters =
-                        (DiagnosticWithParameters2<JetFunctionLiteral, Integer, List<JetType>>) diagnostic;
+                        EXPECTED_PARAMETERS_NUMBER_MISMATCH.cast(diagnostic);
                 JetFunctionLiteral functionLiteral = diagnosticWithParameters.getPsiElement();
                 BindingContext bindingContext =
                         ResolvePackage.getBindingContext(functionLiteral.getContainingJetFile());
@@ -183,7 +184,7 @@ public abstract class ChangeFunctionSignatureFix extends JetIntentionAction<PsiE
             @Override
             public ChangeFunctionSignatureFix createAction(Diagnostic diagnostic) {
                 @SuppressWarnings("unchecked")
-                Object descriptor = ((DiagnosticWithParameters1<PsiNameIdentifierOwner, Object>) diagnostic).getA();
+                Object descriptor = UNUSED_PARAMETER.cast(diagnostic).getA();
 
                 if (descriptor instanceof ValueParameterDescriptor) {
                     return createFix(null, diagnostic.getPsiElement(), (CallableDescriptor) descriptor);
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeTypeFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeTypeFix.java
index b18dcd24a05..18a42347ec4 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeTypeFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/ChangeTypeFix.java
@@ -64,9 +64,7 @@ public class ChangeTypeFix extends JetIntentionAction<JetTypeReference> {
             @Nullable
             @Override
             public IntentionAction createAction(Diagnostic diagnostic) {
-                assert diagnostic.getFactory() == Errors.EXPECTED_PARAMETER_TYPE_MISMATCH;
-                @SuppressWarnings("unchecked")
-                DiagnosticWithParameters1<JetParameter, JetType> diagnosticWithParameters = (DiagnosticWithParameters1<JetParameter, JetType>) diagnostic;
+                DiagnosticWithParameters1<JetParameter, JetType> diagnosticWithParameters = Errors.EXPECTED_PARAMETER_TYPE_MISMATCH.cast(diagnostic);
                 JetTypeReference typeReference = diagnosticWithParameters.getPsiElement().getTypeReference();
                 assert typeReference != null : "EXPECTED_PARAMETER_TYPE_MISMATCH reported on parameter without explicitly declared type";
                 return new ChangeTypeFix(typeReference, diagnosticWithParameters.getA());
@@ -80,9 +78,7 @@ public class ChangeTypeFix extends JetIntentionAction<JetTypeReference> {
             @Nullable
             @Override
             public IntentionAction createAction(Diagnostic diagnostic) {
-                assert diagnostic.getFactory() == Errors.EXPECTED_RETURN_TYPE_MISMATCH;
-                @SuppressWarnings("unchecked")
-                DiagnosticWithParameters1<JetTypeReference, JetType> diagnosticWithParameters = (DiagnosticWithParameters1<JetTypeReference, JetType>) diagnostic;
+                DiagnosticWithParameters1<JetTypeReference, JetType> diagnosticWithParameters = Errors.EXPECTED_RETURN_TYPE_MISMATCH.cast(diagnostic);
                 return new ChangeTypeFix(diagnosticWithParameters.getPsiElement(), diagnosticWithParameters.getA());
             }
         };
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/CreateFunctionFromUsageFix.kt b/idea/src/org/jetbrains/jet/plugin/quickfix/CreateFunctionFromUsageFix.kt
index 2e5b2005700..3f75db7c75c 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/CreateFunctionFromUsageFix.kt
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/CreateFunctionFromUsageFix.kt
@@ -71,6 +71,8 @@ import java.util.ArrayList
 import java.util.Properties
 import org.jetbrains.jet.plugin.caches.resolve.getAnalysisResults
 import org.jetbrains.jet.plugin.caches.resolve.getBindingContext
+import org.jetbrains.jet.lang.diagnostics.DiagnosticFactory
+import org.jetbrains.jet.lang.diagnostics
 
 private val TYPE_PARAMETER_LIST_VARIABLE_NAME = "typeParameterList"
 private val TEMPLATE_FROM_USAGE_FUNCTION_BODY = "New Kotlin Function Body.kt"
@@ -917,9 +919,7 @@ public class CreateFunctionFromUsageFix internal (
         public fun createCreateHasNextFunctionFromUsageFactory(): JetSingleIntentionActionFactory {
             return object : JetSingleIntentionActionFactory() {
                 override fun createAction(diagnostic: Diagnostic?): IntentionAction? {
-                    assert(diagnostic!!.getFactory() == Errors.HAS_NEXT_MISSING || diagnostic.getFactory() == Errors.HAS_NEXT_FUNCTION_NONE_APPLICABLE)
-                    [suppress("UNCHECKED_CAST")]
-                    val diagnosticWithParameters = diagnostic as DiagnosticWithParameters1<JetExpression, JetType>
+                    val diagnosticWithParameters = DiagnosticFactory.cast(diagnostic!!, Errors.HAS_NEXT_MISSING, Errors.HAS_NEXT_FUNCTION_NONE_APPLICABLE)
                     val ownerType = TypeOrExpressionThereof(diagnosticWithParameters.getA(), Variance.IN_VARIANCE)
 
                     val forExpr = QuickFixUtil.getParentElementOfType(diagnostic, javaClass<JetForExpression>()) ?: return null
@@ -932,9 +932,7 @@ public class CreateFunctionFromUsageFix internal (
         public fun createCreateNextFunctionFromUsageFactory(): JetSingleIntentionActionFactory {
             return object : JetSingleIntentionActionFactory() {
                 override fun createAction(diagnostic: Diagnostic?): IntentionAction? {
-                    assert(diagnostic!!.getFactory() == Errors.NEXT_MISSING || diagnostic.getFactory() == Errors.NEXT_NONE_APPLICABLE)
-                    [suppress("UNCHECKED_CAST")]
-                    val diagnosticWithParameters = diagnostic as DiagnosticWithParameters1<JetExpression, JetType>
+                    val diagnosticWithParameters = DiagnosticFactory.cast(diagnostic!!, Errors.NEXT_MISSING, Errors.NEXT_NONE_APPLICABLE)
                     val ownerType = TypeOrExpressionThereof(diagnosticWithParameters.getA(), Variance.IN_VARIANCE)
 
                     val forExpr = QuickFixUtil.getParentElementOfType(diagnostic, javaClass<JetForExpression>()) ?: return null
@@ -971,9 +969,7 @@ public class CreateFunctionFromUsageFix internal (
         public fun createCreateComponentFunctionFromUsageFactory(): JetSingleIntentionActionFactory {
             return object : JetSingleIntentionActionFactory() {
                 override fun createAction(diagnostic: Diagnostic?): IntentionAction? {
-                    assert(diagnostic!!.getFactory() == Errors.COMPONENT_FUNCTION_MISSING)
-                    [suppress("UNCHECKED_CAST")]
-                    val diagnosticWithParameters = (diagnostic as DiagnosticWithParameters2<JetExpression, Name, JetType>)
+                    val diagnosticWithParameters = Errors.COMPONENT_FUNCTION_MISSING.cast(diagnostic!!)
                     val name = diagnosticWithParameters.getA()
                     val componentNumberMatcher = COMPONENT_FUNCTION_PATTERN.matcher(name.getIdentifier())
                     if (!componentNumberMatcher.matches()) return null
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/KotlinSuppressIntentionAction.kt b/idea/src/org/jetbrains/jet/plugin/quickfix/KotlinSuppressIntentionAction.kt
index 97ee7cf9dc0..748c4a1bb76 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/KotlinSuppressIntentionAction.kt
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/KotlinSuppressIntentionAction.kt
@@ -30,7 +30,7 @@ import org.jetbrains.jet.plugin.util.JetPsiPrecedences
 
 public class KotlinSuppressIntentionAction(
         private val suppressAt: JetExpression,
-        private val diagnosticFactory: DiagnosticFactory,
+        private val diagnosticFactory: DiagnosticFactory<*>,
         private val kind: AnnotationHostKind
 ) : SuppressIntentionAction() {
 
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/MapPlatformClassToKotlinFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/MapPlatformClassToKotlinFix.java
index 89af6865108..303b6f404c7 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/MapPlatformClassToKotlinFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/MapPlatformClassToKotlinFix.java
@@ -198,10 +198,8 @@ public class MapPlatformClassToKotlinFix extends JetIntentionAction<JetReference
                 ClassDescriptor platformClass = resolveToClass(typeExpr, context);
                 if (platformClass == null) return null;
 
-                assert diagnostic.getFactory() == Errors.PLATFORM_CLASS_MAPPED_TO_KOTLIN;
-                @SuppressWarnings("unchecked")
                 DiagnosticWithParameters1<JetElement, Collection<ClassDescriptor>> parametrizedDiagnostic =
-                        (DiagnosticWithParameters1<JetElement, Collection<ClassDescriptor>>) diagnostic;
+                        Errors.PLATFORM_CLASS_MAPPED_TO_KOTLIN.cast(diagnostic);
 
                 return new MapPlatformClassToKotlinFix(typeExpr, platformClass, parametrizedDiagnostic.getA());
             }
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixFactoryForTypeMismatchError.java b/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixFactoryForTypeMismatchError.java
index ee9a34753a0..cc9a9ff1f49 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixFactoryForTypeMismatchError.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixFactoryForTypeMismatchError.java
@@ -39,10 +39,7 @@ public class QuickFixFactoryForTypeMismatchError implements JetIntentionActionsF
     public List<IntentionAction> createActions(Diagnostic diagnostic) {
         List<IntentionAction> actions = new LinkedList<IntentionAction>();
 
-        assert diagnostic.getFactory() == Errors.TYPE_MISMATCH;
-        @SuppressWarnings("unchecked")
-        DiagnosticWithParameters2<JetExpression, JetType, JetType> diagnosticWithParameters =
-                (DiagnosticWithParameters2<JetExpression, JetType, JetType>) diagnostic;
+        DiagnosticWithParameters2<JetExpression, JetType, JetType> diagnosticWithParameters = Errors.TYPE_MISMATCH.cast(diagnostic);
         JetExpression expression = diagnosticWithParameters.getPsiElement();
         JetType expectedType = diagnosticWithParameters.getA();
         JetType expressionType = diagnosticWithParameters.getB();
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixes.java b/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixes.java
index a43daabb66e..cbb252a55d5 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixes.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/QuickFixes.java
@@ -30,14 +30,14 @@ import static org.jetbrains.jet.lexer.JetTokens.*;
 
 public class QuickFixes {
 
-    private static final Multimap<DiagnosticFactory, JetIntentionActionsFactory> factories = HashMultimap.create();
-    private static final Multimap<DiagnosticFactory, IntentionAction> actions = HashMultimap.create();
+    private static final Multimap<DiagnosticFactory<?>, JetIntentionActionsFactory> factories = HashMultimap.create();
+    private static final Multimap<DiagnosticFactory<?>, IntentionAction> actions = HashMultimap.create();
 
-    public static Collection<JetIntentionActionsFactory> getActionsFactories(DiagnosticFactory diagnosticFactory) {
+    public static Collection<JetIntentionActionsFactory> getActionsFactories(DiagnosticFactory<?> diagnosticFactory) {
         return factories.get(diagnosticFactory);
     }
 
-    public static Collection<IntentionAction> getActions(DiagnosticFactory diagnosticFactory) {
+    public static Collection<IntentionAction> getActions(DiagnosticFactory<?> diagnosticFactory) {
         return actions.get(diagnosticFactory);
     }
 
diff --git a/idea/src/org/jetbrains/jet/plugin/refactoring/inline/KotlinInlineValHandler.java b/idea/src/org/jetbrains/jet/plugin/refactoring/inline/KotlinInlineValHandler.java
index e3046d15db8..52170cd9f7a 100644
--- a/idea/src/org/jetbrains/jet/plugin/refactoring/inline/KotlinInlineValHandler.java
+++ b/idea/src/org/jetbrains/jet/plugin/refactoring/inline/KotlinInlineValHandler.java
@@ -302,7 +302,7 @@ public class KotlinInlineValHandler extends InlineActionHandler {
         JetFunctionLiteral functionLiteral = functionLiteralExpression.getFunctionLiteral();
         BindingContext context = resolveSessionForBodies.resolveToElement(functionLiteralExpression);
         for (Diagnostic diagnostic : context.getDiagnostics()) {
-            DiagnosticFactory factory = diagnostic.getFactory();
+            DiagnosticFactory<?> factory = diagnostic.getFactory();
             PsiElement element = diagnostic.getPsiElement();
             boolean hasCantInferParameter = factory == Errors.CANNOT_INFER_PARAMETER_TYPE && element.getParent().getParent() == functionLiteral;
             boolean hasUnresolvedItOrThis = factory == Errors.UNRESOLVED_REFERENCE && element.getText().equals("it") &&
diff --git a/idea/tests/org/jetbrains/jet/plugin/highlighter/AbstractDiagnosticMessageTest.java b/idea/tests/org/jetbrains/jet/plugin/highlighter/AbstractDiagnosticMessageTest.java
index 43b7b8bc84a..b5fde8cc5f0 100644
--- a/idea/tests/org/jetbrains/jet/plugin/highlighter/AbstractDiagnosticMessageTest.java
+++ b/idea/tests/org/jetbrains/jet/plugin/highlighter/AbstractDiagnosticMessageTest.java
@@ -78,7 +78,7 @@ public abstract class AbstractDiagnosticMessageTest extends JetLiteFixture {
         String fileData = JetTestUtils.doLoadFile(file);
         Map<String,String> directives = JetTestUtils.parseDirectives(fileData);
         int diagnosticNumber = getDiagnosticNumber(directives);
-        final Set<DiagnosticFactory> diagnosticFactories = getDiagnosticFactories(directives);
+        final Set<DiagnosticFactory<?>> diagnosticFactories = getDiagnosticFactories(directives);
         MessageType messageType = getMessageTypeDirective(directives);
 
         JetFile psiFile = createPsiFile(null, fileName, loadFile(fileName));
@@ -128,10 +128,10 @@ public abstract class AbstractDiagnosticMessageTest extends JetLiteFixture {
     }
 
     @NotNull
-    private static Set<DiagnosticFactory> getDiagnosticFactories(Map<String, String> directives) {
+    private static Set<DiagnosticFactory<?>> getDiagnosticFactories(Map<String, String> directives) {
         String diagnosticsData = directives.get(DIAGNOSTICS_DIRECTIVE);
         assert diagnosticsData != null : DIAGNOSTICS_DIRECTIVE + " should be present.";
-        Set<DiagnosticFactory> diagnosticFactories = Sets.newHashSet();
+        Set<DiagnosticFactory<?>> diagnosticFactories = Sets.newHashSet();
         String[] diagnostics = diagnosticsData.split(" ");
         for (String diagnosticName : diagnostics) {
             String errorMessage = "Can't load diagnostic factory for " + diagnosticName;
@@ -139,7 +139,7 @@ public abstract class AbstractDiagnosticMessageTest extends JetLiteFixture {
                 Field field = Errors.class.getField(diagnosticName);
                 Object value = field.get(null);
                 if (value instanceof DiagnosticFactory) {
-                    diagnosticFactories.add((DiagnosticFactory)value);
+                    diagnosticFactories.add((DiagnosticFactory<?>)value);
                 }
                 else {
                     throw new AssertionError(errorMessage);