Don't parse entries if left brace absent in 'when'

compiler/frontend/src/org/jetbrains/jet/lang/parsing/JetExpressionParsing.java

@@ -780,13 +780,13 @@ public class JetExpressionParsing extends AbstractJetParsing {
 
         // Parse when block
         myBuilder.enableNewlines();
-        expect(LBRACE, "Expecting '{'");
+        if (expect(LBRACE, "Expecting '{'")) {
+            while (!eof() && !at(RBRACE)) {
+                parseWhenEntry();
+            }
 
-        while (!eof() && !at(RBRACE)) {
-            parseWhenEntry();
+            expect(RBRACE, "Expecting '}'");
         }
-
-        expect(RBRACE, "Expecting '}'");
         myBuilder.restoreNewlinesState();
 
         when.done(WHEN);

compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteWhen.kt

@@ -1,3 +1,3 @@
 fun test(a: Any) {
     when (a)<!SYNTAX!><!>
-}<!SYNTAX!><!>
+}

compiler/testData/psi/recovery/WhenWithoutBraces.kt

@@ -0,0 +1,5 @@
+fun test() {
+    when
+
+    bar()
+}

compiler/testData/psi/recovery/WhenWithoutBraces.txt

@@ -0,0 +1,27 @@
+JetFile: WhenWithoutBraces.kt
+  PACKAGE_DIRECTIVE
+    <empty list>
+  FUN
+    PsiElement(fun)('fun')
+    PsiWhiteSpace(' ')
+    PsiElement(IDENTIFIER)('test')
+    VALUE_PARAMETER_LIST
+      PsiElement(LPAR)('(')
+      PsiElement(RPAR)(')')
+    PsiWhiteSpace(' ')
+    BLOCK
+      PsiElement(LBRACE)('{')
+      PsiWhiteSpace('\n    ')
+      WHEN
+        PsiElement(when)('when')
+        PsiErrorElement:Expecting '{'
+          <empty list>
+      PsiWhiteSpace('\n\n    ')
+      CALL_EXPRESSION
+        REFERENCE_EXPRESSION
+          PsiElement(IDENTIFIER)('bar')
+        VALUE_ARGUMENT_LIST
+          PsiElement(LPAR)('(')
+          PsiElement(RPAR)(')')
+      PsiWhiteSpace('\n')
+      PsiElement(RBRACE)('}')

compiler/tests/org/jetbrains/jet/parsing/JetParsingTestGenerated.java

@@ -1015,6 +1015,11 @@ public class JetParsingTestGenerated extends AbstractJetParsingTest {
                 doParsingTest("compiler/testData/psi/recovery/ValueParameterNoTypeRecovery.kt");
             }
             
+            @TestMetadata("WhenWithoutBraces.kt")
+            public void testWhenWithoutBraces() throws Exception {
+                doParsingTest("compiler/testData/psi/recovery/WhenWithoutBraces.kt");
+            }
+            
             @TestMetadata("WhileWithEmptyCondition.kt")
             public void testWhileWithEmptyCondition() throws Exception {
                 doParsingTest("compiler/testData/psi/recovery/WhileWithEmptyCondition.kt");