[java-psi] PsiMethodCallExpressionImpl: on ambiguous call use upper bound of types if possible

GitOrigin-RevId: 7de48b2542e2fe0a0f8503ab3dd3c4d34784747c

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodCallExpressionImpl.java

@@ -164,7 +164,8 @@ public class PsiMethodCallExpressionImpl extends ExpressionPsiElement implements
           theOnly = type;
         }
         else if (!theOnly.equals(type)) {
-          return null;
+          theOnly = GenericsUtil.getLeastUpperBound(type, theOnly, file.getManager());
+          if (theOnly == null) return null;
         }
       }
 

java/java-tests/testData/codeInsight/completion/normal/AmbiguousCallLeastUpperBound.java

@@ -0,0 +1,8 @@
+class Main {
+  String foo(int x) { return "1";}
+  StringBuilder foo(String x) { return new StringBuilder();}
+
+  void test() {
+    foo(1.25).le<caret>
+  }
+}

java/java-tests/testData/codeInsight/completion/normal/AmbiguousCallLeastUpperBound_after.java

@@ -0,0 +1,8 @@
+class Main {
+  String foo(int x) { return "1";}
+  StringBuilder foo(String x) { return new StringBuilder();}
+
+  void test() {
+    foo(1.25).length()<caret>
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/completion/NormalCompletionTest.java

@@ -3251,4 +3251,11 @@ public class NormalCompletionTest extends NormalCompletionTestCase {
     myFixture.completeBasic();
     assertTrue(myFixture.getLookupElementStrings().contains("A"));
   }
+
+  @NeedsIndex.ForStandardLibrary
+  public void testAmbiguousCallLeastUpperBound() {
+    configureByTestName();
+    myFixture.completeBasic();
+    myFixture.checkResultByFile(getTestName(false) + "_after.java");
+  }
 }

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/Java8ExpressionsCheckTest.java

@@ -345,19 +345,24 @@ public class Java8ExpressionsCheckTest extends LightDaemonAnalyzerTestCase {
 
     PsiMethodCallExpression outerCall = (PsiMethodCallExpression) innerCall.getParent().getParent();
 
-    assertAmbiguous(outerCall);
-    assertAmbiguous(innerCall);
+    assertAmbiguous(outerCall, "java.util.Collection<? extends java.lang.Object>");
+    assertAmbiguous(innerCall, "java.util.Collection<? extends java.lang.Object>");
 
     dropCaches();
 
-    assertAmbiguous(innerCall);
-    assertAmbiguous(outerCall);
+    assertAmbiguous(innerCall, "java.util.Collection<? extends java.lang.Object>");
+    assertAmbiguous(outerCall, "java.util.Collection<? extends java.lang.Object>");
   }
 
-  private static void assertAmbiguous(PsiMethodCallExpression call) {
+  private static void assertAmbiguous(PsiMethodCallExpression call, @Nullable String expectedType) {
     assertNull(call.getText(), call.resolveMethod());
     assertSize(2, call.multiResolve(false));
-    assertNull(call.getText(), call.getType());
+    PsiType type = call.getType();
+    if (expectedType == null) {
+      assertNull(call.getText(), type);
+    } else {
+      assertEquals(call.getText(), expectedType, type.getCanonicalText());
+    }
   }
 
   public void testAdditionalConstraintsBasedOnLambdaResolution() {