javaClass<T> is supported for reified T

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

@@ -3810,7 +3810,7 @@ The "returned" value of try expression with no finally is either the last expres
         return StackValue.onStack(type);
     }
 
-    private void putReifierMarkerIfTypeIsReifiedParameter(@NotNull JetType type, @NotNull String markerMethodName) {
+    public void putReifierMarkerIfTypeIsReifiedParameter(@NotNull JetType type, @NotNull String markerMethodName) {
         TypeParameterDescriptor typeParameterDescriptor = TypeUtils.getTypeParameterDescriptorOrNull(type);
         if (typeParameterDescriptor != null && typeParameterDescriptor.isReified()) {
             v.iconst(typeParameterDescriptor.getIndex());

compiler/backend/src/org/jetbrains/jet/codegen/inline/ReifiedTypeInliner.kt

@@ -37,6 +37,7 @@ public class ReifiedTypeInliner(private val parametersMapping: ReifiedTypeParame
         public val NEW_ARRAY_MARKER_METHOD_NAME: String = "reifyNewArray"
         public val CHECKCAST_MARKER_METHOD_NAME: String = "reifyCheckcast"
         public val INSTANCEOF_MARKER_METHOD_NAME: String = "reifyInstanceof"
+        public val JAVA_CLASS_MARKER_METHOD_NAME: String = "reifyJavaClass"
     }
 
     public fun reifyInstructions(instructions: InsnList) {
@@ -62,6 +63,7 @@ public class ReifiedTypeInliner(private val parametersMapping: ReifiedTypeParame
                 NEW_ARRAY_MARKER_METHOD_NAME -> processNewArray(insn, asmType)
                 CHECKCAST_MARKER_METHOD_NAME -> processCheckcast(insn, asmType)
                 INSTANCEOF_MARKER_METHOD_NAME -> processInstanceof(insn, asmType)
+                JAVA_CLASS_MARKER_METHOD_NAME -> processJavaClass(insn, asmType)
                 else -> false
             }) {
                 return
@@ -88,6 +90,13 @@ public class ReifiedTypeInliner(private val parametersMapping: ReifiedTypeParame
         return true
     }
 
+    private fun processJavaClass(insn: MethodInsnNode, parameter: Type): Boolean {
+        val next = insn.getNext()
+        if (next !is LdcInsnNode) return false
+        next.cst = parameter
+        return true
+    }
+
     private fun getParameterIndex(insn: MethodInsnNode): Int? {
         val prev = insn.getPrevious()!!
 

compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/JavaClassFunction.java

@@ -21,6 +21,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.codegen.ExpressionCodegen;
 import org.jetbrains.jet.codegen.StackValue;
+import org.jetbrains.jet.codegen.inline.ReifiedTypeInliner;
 import org.jetbrains.jet.lang.psi.JetElement;
 import org.jetbrains.jet.lang.psi.JetExpression;
 import org.jetbrains.jet.lang.resolve.calls.callUtil.CallUtilPackage;
@@ -49,7 +50,12 @@ public class JavaClassFunction extends IntrinsicMethod {
                 (JetElement) element, codegen.getBindingContext());
         JetType returnType = resolvedCall.getResultingDescriptor().getReturnType();
         assert returnType != null;
-        putJavaLangClassInstance(v, codegen.getState().getTypeMapper().mapType(returnType.getArguments().get(0).getType()));
+
+        JetType type = returnType.getArguments().get(0).getType();
+
+        codegen.putReifierMarkerIfTypeIsReifiedParameter(type, ReifiedTypeInliner.JAVA_CLASS_MARKER_METHOD_NAME);
+
+        putJavaLangClassInstance(v, codegen.getState().getTypeMapper().mapType(type));
 
         return getType(Class.class);
     }

compiler/testData/codegen/boxWithStdlib/reified/defaultJavaClass.kt

@@ -0,0 +1,17 @@
+import kotlin.test.assertEquals
+
+inline fun <reified T> foo(x: Class<T> = javaClass<T>()): String = x.getName()
+
+inline fun <reified R> bar(x: R): String = foo<R>()
+
+fun box(): String {
+    assertEquals("java.lang.String", foo<String>())
+    assertEquals("java.lang.Integer", foo<Int>())
+    assertEquals("java.lang.Object", foo<Any>())
+
+    assertEquals("java.lang.String", bar("abc"))
+    assertEquals("java.lang.Integer", bar(1))
+    assertEquals("java.lang.Object", bar(Any()))
+
+    return "OK"
+}

compiler/testData/codegen/boxWithStdlib/reified/javaClass.kt

@@ -0,0 +1,12 @@
+import kotlin.test.assertEquals
+
+inline fun<reified T> javaClassName(): String {
+    return javaClass<T>().getName()
+}
+
+fun box(): String {
+    assertEquals("java.lang.String", javaClassName<String>())
+    assertEquals("java.lang.Integer", javaClassName<Int>())
+    assertEquals("java.lang.Object", javaClassName<Any>())
+    return "OK"
+}

compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java

@@ -2426,6 +2426,12 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
             doTestWithStdlib(fileName);
         }
 
+        @TestMetadata("defaultJavaClass.kt")
+        public void testDefaultJavaClass() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reified/defaultJavaClass.kt");
+            doTestWithStdlib(fileName);
+        }
+
         @TestMetadata("filterIsInstance.kt")
         public void testFilterIsInstance() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reified/filterIsInstance.kt");
@@ -2438,6 +2444,12 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
             doTestWithStdlib(fileName);
         }
 
+        @TestMetadata("javaClass.kt")
+        public void testJavaClass() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reified/javaClass.kt");
+            doTestWithStdlib(fileName);
+        }
+
         @TestMetadata("newArrayInt.kt")
         public void testNewArrayInt() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reified/newArrayInt.kt");

core/runtime.jvm/src/kotlin/jvm/internal/Intrinsics.java

@@ -118,6 +118,10 @@ public class Intrinsics {
         throwUndefinedForReified();
     }
 
+    public static void reifyJavaClass(int parameterTypeIndex) {
+        throwUndefinedForReified();
+    }
+
     public static <T extends Throwable> T sanitizeStackTrace(T throwable) {
         StackTraceElement[] stackTrace = throwable.getStackTrace();
         ArrayList<StackTraceElement> list = new ArrayList<StackTraceElement>(stackTrace.length);