JS backend: fixed wrong NPE when casting to generic type.

js/js.tests/test/org/jetbrains/k2js/test/semantics/CastTest.java

@@ -32,6 +32,10 @@ public final class CastTest extends AbstractExpressionTest {
         checkFooBoxIsOk();
     }
 
+    public void testCastToGenericType() throws Exception {
+        checkFooBoxIsOk();
+    }
+
     public void testSmartCastInExtensionFunction() throws Exception {
         checkFooBoxIsOk();
     }

js/js.translator/src/org/jetbrains/k2js/translate/expression/ExpressionVisitor.java

@@ -17,7 +17,6 @@
 package org.jetbrains.k2js.translate.expression;
 
 import com.google.dart.compiler.backend.js.ast.*;
-import com.intellij.psi.tree.IElementType;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
@@ -29,6 +28,7 @@ import org.jetbrains.jet.lang.resolve.BindingContextUtils;
 import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
 import org.jetbrains.jet.lang.resolve.constants.NullValue;
 import org.jetbrains.jet.lang.types.JetType;
+import org.jetbrains.jet.lang.types.TypeUtils;
 import org.jetbrains.jet.lexer.JetTokens;
 import org.jetbrains.k2js.translate.context.TemporaryVariable;
 import org.jetbrains.k2js.translate.context.TranslationContext;
@@ -347,9 +347,12 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
         if (expression.getOperationReference().getReferencedNameElementType() != JetTokens.AS_KEYWORD)
             return jsExpression.source(expression);
 
-        JetType rightType = BindingContextUtils.getNotNull(context.bindingContext(), BindingContext.TYPE, expression.getRight());
+        JetTypeReference right = expression.getRight();
+        assert right != null;
+
+        JetType rightType = BindingContextUtils.getNotNull(context.bindingContext(), BindingContext.TYPE, right);
         JetType leftType = BindingContextUtils.getNotNull(context.bindingContext(), BindingContext.EXPRESSION_TYPE, expression.getLeft());
-        if (rightType.isNullable() || !leftType.isNullable()) {
+        if (TypeUtils.isNullableType(rightType) || !TypeUtils.isNullableType(leftType)) {
             return jsExpression.source(expression);
         }
 

js/js.translator/testData/expression/cast/cases/castToGenericType.kt

@@ -0,0 +1,74 @@
+package foo
+
+class A(val s: String)
+
+fun castsNotNullToNullableT<T>(a: Any) {
+    a as T
+    a as T?
+    a as? T
+    a as? T?
+}
+
+fun castsNullableToNullableT<T>(a: Any?) {
+    a as T
+    a as T?
+    a as? T
+    a as? T?
+}
+
+
+fun castsNotNullToNotNullT<T : Any>(a: Any) {
+    a as T
+    a as T?
+    a as? T
+    a as? T?
+}
+
+fun castNullableToNotNullT<T : Any>(a: Any?) {
+    a as T
+}
+
+fun castsNullableToNotNullT<T : Any>(a: Any?) {
+    a as T?
+    a as? T
+    a as? T?
+}
+
+fun test(f: () -> Unit) {
+    try {
+        f()
+    }
+    catch(e: Exception) {
+        throw Exception("Failed in $f with unexpected exception $e")
+    }
+}
+
+fun fails(f: () -> Unit) {
+    try {
+        f()
+    }
+    catch(e: Exception) {
+        return
+    }
+
+    throw Exception("Expected an exception to be thrown from $f")
+}
+
+fun box(): String {
+    val a = A("OK")
+
+    test { castsNotNullToNullableT<A>(a) }
+
+    test { castsNullableToNullableT<A>(a) }
+    test { castsNullableToNullableT<A>(null) }
+
+    test { castsNotNullToNotNullT<A>(a) }
+
+    test { castsNullableToNotNullT<A>(a) }
+    test { castsNullableToNotNullT<A>(null) }
+
+    test  { castNullableToNotNullT<A>(a) }
+    fails { castNullableToNotNullT<A>(null) }
+
+    return "OK"
+}