lambda: check assignable takes into account wildcards (IDEA-108195)

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

@@ -151,7 +151,7 @@ public class LambdaUtil {
       }
       return false;
     }
-    final PsiClassType.ClassResolveResult resolveResult = PsiUtil.resolveGenericsClassInType(leftType);
+    final PsiClassType.ClassResolveResult resolveResult = PsiUtil.resolveGenericsClassInType(GenericsUtil.eliminateWildcards(leftType));
     final PsiClass psiClass = resolveResult.getElement();
     if (psiClass instanceof PsiAnonymousClass) {
       return isAcceptable(lambdaExpression, ((PsiAnonymousClass)psiClass).getBaseClassType(), checkReturnType);

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/highlighting/IDEA108195.java

@@ -0,0 +1,12 @@
+class Demo {
+
+    Function<Supplier<Double>, ? extends Supplier<Double>> mapper2 = (sa) -> () -> sa.get() + 1.0;
+
+    interface Supplier<T> {
+      public T get();
+    }
+  
+    interface Function<T, R> {
+      public R apply(T t);
+    }
+}

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

@@ -87,6 +87,7 @@ public class LambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
   public void testConditionalInferenceFromOppositePart() { doTest(); }
   public void testDeclaredTypeParameterBoundsAndUnboundedWildcard() { doTest(); }
   public void testConflictResolution() throws Exception {doTest();}
+  public void testIDEA108195() throws Exception {doTest();}
 
   private void doTest() {
     doTest(false);