redundant cast: recapture wildcards for non-physical elements (IDEA-153166)

java/java-psi-api/src/com/intellij/psi/util/PsiUtil.java

@@ -764,6 +764,9 @@ public final class PsiUtil extends PsiUtilCore {
     return null;
   }
 
+  /**
+   * Applies capture conversion to the type in context
+   */
   @NotNull
   public static PsiType captureToplevelWildcards(@NotNull final PsiType type, @NotNull final PsiElement context) {
     if (type instanceof PsiClassType) {
@@ -811,6 +814,38 @@ public final class PsiUtil extends PsiUtilCore {
     return type;
   }
 
+  /**
+   * Opens top level captured wildcards and remap them according to the context.
+   * The only valid purpose: allow to speculate on non-physical expressions about types, e.g. to detect redundant casts with 'wildcards'
+   */
+  public static PsiType recaptureWildcards(PsiType type, PsiElement context) {
+    if (type instanceof PsiClassType) {
+      final PsiClassType.ClassResolveResult resolveResult = ((PsiClassType)type).resolveGenerics();
+      final PsiClass aClass = resolveResult.getElement();
+      if (aClass != null) {
+        final PsiSubstitutor substitutor = resolveResult.getSubstitutor();
+
+        PsiSubstitutor resultSubstitution = null;
+        for (PsiTypeParameter parameter : substitutor.getSubstitutionMap().keySet()) {
+          final PsiType substitute = substitutor.substitute(parameter);
+          if (substitute instanceof PsiCapturedWildcardType) {
+            if (resultSubstitution == null) resultSubstitution = substitutor;
+            resultSubstitution = resultSubstitution.put(parameter, ((PsiCapturedWildcardType)substitute).getWildcard());
+          }
+        }
+
+        if (resultSubstitution != null) {
+          final PsiElementFactory factory = JavaPsiFacade.getElementFactory(context.getProject());
+          return captureToplevelWildcards(factory.createType(aClass, resultSubstitution), context);
+        }
+      }
+    }
+    else if (type instanceof PsiArrayType) {
+      return recaptureWildcards(((PsiArrayType)type).getComponentType(), context).createArrayType();
+    }
+    return type;
+  }
+
   public static boolean isInsideJavadocComment(PsiElement element) {
     return PsiTreeUtil.getParentOfType(element, PsiDocComment.class, true) != null;
   }

java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java

@@ -385,7 +385,7 @@ public class RedundantCastUtil {
             if (oldMethod.equals(newResult.getElement()) &&
                 (!(newCall instanceof PsiCallExpression) || 
                  oldAnonymousClass != null && newAnonymousClass != null && Comparing.equal(oldAnonymousClass.getBaseClassType(), newAnonymousClass.getBaseClassType()) || 
-                 Comparing.equal(((PsiCallExpression)newCall).getType(), ((PsiCallExpression)expression).getType())) &&
+                 Comparing.equal(PsiUtil.recaptureWildcards(((PsiCallExpression)newCall).getType(), expression), ((PsiCallExpression)expression).getType())) &&
                 newResult.isValidResult()) {
               if (!(newArgs[i] instanceof PsiFunctionalExpression) || castType != null && castType.equals(((PsiFunctionalExpression)newArgs[i]).getFunctionalInterfaceType())) {
                 addToResults(cast);

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/redundantCast/CapturedWildcardInCast.java

@@ -0,0 +1,9 @@
+
+import java.util.function.IntFunction;
+import java.util.stream.Stream;
+
+class MyTest {
+  private static void getArguments(final Stream<Class<String>> classStream) {
+    final Class<?>[] classes = classStream.toArray(((<warning descr="Casting '(value) -> new Class<?>[value]' to 'IntFunction<Class<?>[]>' is redundant">IntFunction<Class<?>[]></warning>) (value) -> new Class<?>[value]) );
+  }
+}

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

@@ -61,6 +61,10 @@ public class LambdaRedundantCastTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testCapturedWildcardInCast() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(BASE_PATH + "/" + getTestName(false) + ".java", true, false);
   }