JS: report error when js() produces empty AST

compiler/testData/diagnostics/testsWithJsStdLib/jsCode/noJavaScriptProduced.kt

@@ -0,0 +1,16 @@
+fun test() {
+    js(<!JSCODE_NO_JAVASCRIPT_PRODUCED!>""<!>)
+    js(<!JSCODE_NO_JAVASCRIPT_PRODUCED!>" "<!>)
+    js(<!JSCODE_NO_JAVASCRIPT_PRODUCED!>"""
+               """<!>)
+
+    val empty = ""
+    js(<!JSCODE_NO_JAVASCRIPT_PRODUCED!>empty<!>)
+
+    val whitespace = "  "
+    js(<!JSCODE_NO_JAVASCRIPT_PRODUCED!>whitespace<!>)
+
+    val multiline = """
+    """
+    js(<!JSCODE_NO_JAVASCRIPT_PRODUCED!>multiline<!>)
+}

compiler/testData/diagnostics/testsWithJsStdLib/jsCode/noJavaScriptProduced.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(): kotlin.Unit

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestWithJsStdLibGenerated.java

@@ -257,6 +257,12 @@ public class JetDiagnosticsTestWithJsStdLibGenerated extends AbstractJetDiagnost
             doTest(fileName);
         }
 
+        @TestMetadata("noJavaScriptProduced.kt")
+        public void testNoJavaScriptProduced() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/testsWithJsStdLib/jsCode/noJavaScriptProduced.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("warning.kt")
         public void testWarning() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/testsWithJsStdLib/jsCode/warning.kt");

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/DefaultErrorMessagesJs.kt

@@ -38,6 +38,7 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by Delegates.lazy {
         put(ErrorsJs.REFERENCE_TO_BUILTIN_MEMBERS_NOT_SUPPORTED, "Callable references for builtin members are not supported yet: ''{0}''", RenderFirstLineOfElementText)
         put(ErrorsJs.NON_TOPLEVEL_CLASS_DECLARATION, "Non-toplevel {0} declarations not supported yet", Renderers.STRING)
         put(ErrorsJs.SECONDARY_CONSTRUCTOR, "Secondary constructors not supported yet")
+        put(ErrorsJs.JSCODE_NO_JAVASCRIPT_PRODUCED, "Argument must be non-empty JavaScript code")
         put(ErrorsJs.INLINE_CALL_CYCLE, "The call is a part of inline cycle")
 
         this

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/ErrorsJs.java

@@ -45,6 +45,7 @@ public interface ErrorsJs {
     DiagnosticFactory1<JetElement, JetElement> REFERENCE_TO_BUILTIN_MEMBERS_NOT_SUPPORTED = DiagnosticFactory1.create(ERROR, DEFAULT);
     DiagnosticFactory1<JetNamedDeclaration, String> NON_TOPLEVEL_CLASS_DECLARATION = DiagnosticFactory1.create(ERROR, DECLARATION_NAME);
     DiagnosticFactory0<JetNamedDeclaration> SECONDARY_CONSTRUCTOR = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE_OR_DEFAULT);
+    DiagnosticFactory0<JetExpression> JSCODE_NO_JAVASCRIPT_PRODUCED = DiagnosticFactory0.create(ERROR, DEFAULT);
     DiagnosticFactory0<PsiElement> INLINE_CALL_CYCLE = DiagnosticFactory0.create(ERROR, DEFAULT);
 
     @SuppressWarnings("UnusedDeclaration")

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsCallChecker.kt

@@ -43,6 +43,7 @@ import org.jetbrains.kotlin.resolve.constants.evaluate.ConstantExpressionEvaluat
 import org.jetbrains.kotlin.types.JetType
 
 import com.intellij.openapi.util.TextRange
+import org.jetbrains.kotlin.js.parser.parse
 import java.io.StringReader
 
 import kotlin.platform.platformStatic
@@ -81,18 +82,16 @@ public class JsCallChecker : CallChecker {
         }
 
         val code = evaluationResult.getValue() as String
-        val reader = StringReader(code)
         val errorReporter = JsCodeErrorReporter(argument, code, context.trace)
-        Context.enter().setErrorReporter(errorReporter)
 
         try {
-            val ts = TokenStream(reader, "js", 0)
+            val statements = parse(code, errorReporter, insideFunction = true)
-            val parser = Parser(IRFactory(ts), /* insideFunction = */ true)
+
-            parser.parse(ts)
+            if (statements.size() == 0) {
+                context.trace.report(ErrorsJs.JSCODE_NO_JAVASCRIPT_PRODUCED.on(argument))
+            }
         } catch (e: AbortParsingException) {
             // ignore
-        } finally {
-            Context.exit()
         }
     }
 }