Fix for KT-14205

If detected unfinished expression it passed through, added warning on action "Convert Java to Kotlin", if Java files contains syntax errors.

idea/src/org/jetbrains/kotlin/idea/actions/JavaToKotlinAction.kt

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.idea.actions
 
+import com.intellij.codeInsight.navigation.NavigationUtil
 import com.intellij.ide.scratch.ScratchFileService
 import com.intellij.ide.scratch.ScratchRootType
 import com.intellij.openapi.actionSystem.AnAction
@@ -33,8 +34,10 @@ import com.intellij.openapi.vfs.VfsUtilCore
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.openapi.vfs.VirtualFileVisitor
 import com.intellij.psi.PsiDocumentManager
+import com.intellij.psi.PsiErrorElement
 import com.intellij.psi.PsiJavaFile
 import com.intellij.psi.PsiManager
+import com.intellij.psi.util.PsiTreeUtil
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.idea.j2k.IdeaJavaToKotlinServices
 import org.jetbrains.kotlin.idea.j2k.J2kPostProcessor
@@ -61,6 +64,8 @@ class JavaToKotlinAction : AnAction() {
             }
         }
 
+        val title = "Convert Java to Kotlin"
+
         private fun saveResults(javaFiles: List<PsiJavaFile>, convertedTexts: List<String>): List<VirtualFile> {
             val result = ArrayList<VirtualFile>()
             for ((psiFile, text) in javaFiles.zip(convertedTexts)) {
@@ -99,7 +104,7 @@ class JavaToKotlinAction : AnAction() {
                 converterResult = converter.filesToKotlin(javaFiles, J2kPostProcessor(formatCode = true), ProgressManager.getInstance().progressIndicator)
             }
 
-            val title = "Convert Java to Kotlin"
+
             if (!ProgressManager.getInstance().runProcessWithProgressSynchronously(
                     {
                         runReadAction(::convert)
@@ -145,6 +150,30 @@ class JavaToKotlinAction : AnAction() {
     override fun actionPerformed(e: AnActionEvent) {
         val javaFiles = selectedJavaFiles(e).toList()
         val project = CommonDataKeys.PROJECT.getData(e.dataContext)!!
+
+        val firstSyntaxError = javaFiles.asSequence().map { PsiTreeUtil.findChildOfType(it, PsiErrorElement::class.java) }.firstOrNull()
+
+        if (firstSyntaxError != null) {
+            val count = javaFiles.filter { PsiTreeUtil.hasErrorElements(it) }.count()
+            val question = firstSyntaxError.containingFile.name +
+                           (if (count > 1) " and ${count - 1} more Java files" else " file") +
+                           " contain syntax errors, the conversion result may be incorrect"
+
+            val okText = "Investigate Errors"
+            val cancelText = "Proceed with Conversion"
+            if (Messages.showOkCancelDialog(
+                    project,
+                    question,
+                    title,
+                    okText,
+                    cancelText,
+                    Messages.getWarningIcon()
+            ) == Messages.OK) {
+                NavigationUtil.activateFileWithPsiElement(firstSyntaxError.navigationElement)
+                return
+            }
+        }
+
         convertFiles(javaFiles, project)
     }
 

j2k/src/org/jetbrains/kotlin/j2k/ExpressionConverter.kt

@@ -546,7 +546,11 @@ class DefaultExpressionConverter : JavaElementVisitor(), ExpressionConverter {
             return
         }
 
-        val referenceName = expression.referenceName!!
+        val referenceName = expression.referenceName ?: run {
+            result = LiteralExpression(expression.text).assignNoPrototype()
+            return
+        }
+
         val target = expression.resolve()
 
         val isNullable = target is PsiVariable && isNullable(target)

j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.java

@@ -0,0 +1,7 @@
+public class JavaClass {
+    public String v = "";
+    public void m(String s) {
+        s.
+        this.v.
+    }
+}

j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.kt

@@ -0,0 +1,8 @@
+// ERROR: The expression cannot be a selector (occur after a dot)
+class JavaClass {
+    var v = ""
+    fun m(s: String) {
+        s.
+                this.v.
+    }
+}

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterForWebDemoTestGenerated.java

@@ -3003,6 +3003,12 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/spaceBeforeAssignment.java");
             doTest(fileName);
         }
+
+        @TestMetadata("unfinishedReferenceExpression.java")
+        public void testUnfinishedReferenceExpression() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.java");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("j2k/testData/fileOrElement/kotlinApiAccess")

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterSingleFileTestGenerated.java

@@ -3003,6 +3003,12 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/spaceBeforeAssignment.java");
             doTest(fileName);
         }
+
+        @TestMetadata("unfinishedReferenceExpression.java")
+        public void testUnfinishedReferenceExpression() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.java");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("j2k/testData/fileOrElement/kotlinApiAccess")