Debugger: fix evaluate expression for traits

idea/src/org/jetbrains/jet/plugin/debugger/evaluate/KotlinEvaluationBuilder.kt

@@ -396,6 +396,9 @@ fun EvaluationContextImpl.findLocalVariable(name: String, asmType: Type?, checkT
 
                 val this0 = findLocalVariable(AsmUtil.CAPTURED_THIS_FIELD, asmType, checkType = true, failIfNotFound = false)
                 if (this0 != null) return this0
+
+                val `$this` = findLocalVariable("\$this", asmType, checkType = false, failIfNotFound = false)
+                if (`$this` != null) return `$this`
             }
             else -> {
                 val eval4j = JDIEval(frame.virtualMachine()!!,
@@ -442,7 +445,8 @@ fun EvaluationContextImpl.findLocalVariable(name: String, asmType: Type?, checkT
 
                 fun findCapturedVal(name: String): Value? {
                     var result: Value? = null
-                    var thisObj: Value? = frame.thisObject().asValue()
+                    val thisObject = frame.thisObject() ?: return null
+                    var thisObj: Value? = thisObject.asValue()
 
                     while (result == null && thisObj != null) {
                         result = eval4j.getField(thisObj!!, name, asmType, checkType)

idea/testData/debugger/tinyApp/outs/extractThisInTrait.out

@@ -0,0 +1,9 @@
+LineBreakpoint created at extractThisInTrait.kt:10
+!JDK_HOME!\bin\java -agentlib:jdwp=transport=dt_socket,address=!HOST_NAME!:!HOST_PORT!,suspend=y,server=n -Dfile.encoding=!FILE_ENCODING! -classpath !APP_PATH!\classes;!KOTLIN_RUNTIME!;!CUSTOM_LIBRARY!;!RT_JAR! extractThisInTrait.ExtractThisInTraitPackage
+Connected to the target VM, address: '!HOST_NAME!:PORT_NAME!', transport: 'socket'
+extractThisInTrait.kt:10
+Compile bytecode for prop
+Compile bytecode for this.prop
+Disconnected from the target VM, address: '!HOST_NAME!:PORT_NAME!', transport: 'socket'
+
+Process finished with exit code 0

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/extractThisInTrait.kt

@@ -0,0 +1,23 @@
+package extractThisInTrait
+
+fun main(args: Array<String>) {
+    TImpl().foo()
+}
+
+trait T {
+    fun foo() {
+        //Breakpoint!
+        val a = 1
+    }
+
+    val prop: Int
+        get() = 1
+}
+
+class TImpl(): T
+
+// EXPRESSION: prop
+// RESULT: 1: I
+
+// EXPRESSION: this.prop
+// RESULT: 1: I

idea/tests/org/jetbrains/jet/plugin/debugger/evaluate/KotlinEvaluateExpressionTestGenerated.java

@@ -118,6 +118,12 @@ public class KotlinEvaluateExpressionTestGenerated extends AbstractKotlinEvaluat
             doSingleBreakpointTest(fileName);
         }
 
+        @TestMetadata("extractThisInTrait.kt")
+        public void testExtractThisInTrait() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/extractThisInTrait.kt");
+            doSingleBreakpointTest(fileName);
+        }
+
         @TestMetadata("extractVariablesFromCall.kt")
         public void testExtractVariablesFromCall() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/extractVariablesFromCall.kt");