[groovy] honor returns when computing last statement (IDEA-178598)

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/codeInspection/utils/ControlFlowUtils.java

@@ -415,20 +415,10 @@ public class ControlFlowUtils {
   }
 
   private static boolean statementIsLastInBlock(@NotNull GrStatementOwner block, @NotNull GrStatement statement) {
-    final GrStatement[] statements = block.getStatements();
-    for (int i = statements.length - 1; i >= 0; i--) {
-      final GrStatement childStatement = statements[i];
-      if (statement.equals(childStatement)) {
-        return true;
-      }
-      if (!(childStatement instanceof GrReturnStatement)) {
-        return false;
-      }
-    }
-    return false;
+    GrStatement lastStatement = ArrayUtil.getLastElement(block.getStatements());
+    return statement == lastStatement;
   }
 
-
   @NotNull
   public static List<GrStatement> collectReturns(@Nullable PsiElement element) {
     return collectReturns(element, element instanceof GrCodeBlock || element instanceof GroovyFile);

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/highlighting/GrInspectionTest.groovy

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2016 JetBrains s.r.o.
+ * Copyright 2000-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -292,6 +292,21 @@ for(i in []) {
     print 4
   }
 }
+
+for (i in []) {
+  if (cond) {
+    continue
+  }
+  return
+}
+
+for (i in []) {
+  if (cond) {
+    <warning descr="continue is unnecessary as the last statement in a loop">continue</warning>
+  } else {
+    return
+  }
+}
 ''', GroovyUnnecessaryContinueInspection)
   }