reject functional expressions as conditional condition (IDEA-184667)

java/java-psi-api/src/com/intellij/psi/LambdaUtil.java

@@ -337,9 +337,9 @@ public class LambdaUtil {
     PsiElement parent = expression.getParent();
     PsiElement element = expression;
     while (parent instanceof PsiParenthesizedExpression || parent instanceof PsiConditionalExpression) {
-      if (parent instanceof PsiConditionalExpression &&
-          ((PsiConditionalExpression)parent).getThenExpression() != element &&
-          ((PsiConditionalExpression)parent).getElseExpression() != element) break;
+      if (parent instanceof PsiConditionalExpression && ((PsiConditionalExpression)parent).getCondition() == element) {
+        return PsiType.BOOLEAN;
+      }
       element = parent;
       parent = parent.getParent();
     }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/ConditionalBooleanAsFunctionalInterfaceType.java

@@ -0,0 +1,5 @@
+class Test {
+  {
+    boolean condition = <error descr="boolean is not a functional interface">() -> {}</error> ? true : false;
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java

@@ -163,6 +163,7 @@ public class NewLambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
   public void testIDEA174924() { doTest(); }
   public void testVoidValueCompatibilityWithBreakInSwitch() { doTest(); }
   public void testExceptionInferenceForVarargMethods() { doTest(); }
+  public void testConditionalBooleanAsFunctionalInterfaceType() { doTest(); }
 
   private void doTest() {
     IdeaTestUtil.setTestVersion(JavaSdkVersion.JDK_1_8, getModule(), getTestRootDisposable());