Fix multiple issues with NewClassTrees that have enclosing expressions (#1191)

Fixes #1188, exactly as suggested in that issue. This both simplifies
the code and fixes a false negative with `@Nullable` enclosing
expressions.

Author: msridhar

nullaway/src/main/java/com/uber/nullaway/NullAway.java

@@ -441,9 +441,15 @@ public Description matchNewClass(NewClassTree tree, VisitorState state) {
     if (methodSymbol == null) {
       throw new RuntimeException("not expecting unresolved method here");
     }
+    ExpressionTree enclosingExpression = tree.getEnclosingExpression();
+    if (enclosingExpression != null) {
+      // technically this is not a dereference; there is a requireNonNull() call in the
+      // bytecode.  but it's close enough for error reporting
+      state.reportMatch(matchDereference(enclosingExpression, tree, state));
+    }
     List<? extends ExpressionTree> actualParams = tree.getArguments();
-    if (tree.getClassBody() != null && actualParams.size() > 0) {
-      // passing parameters to constructor of anonymous class
+    if (tree.getClassBody() != null) {
+      // invoking constructor of anonymous class
       // this constructor just invokes the constructor of the superclass, and
       // in the AST does not have the parameter nullability annotations from the superclass.
       // so, treat as if the superclass constructor is being invoked directly
@@ -1861,18 +1867,7 @@ private Description handleInvocation(
       Symbol.MethodSymbol methodSymbol,
       List<? extends ExpressionTree> actualParams) {
     List<VarSymbol> formalParams = methodSymbol.getParameters();
-
     boolean varArgsMethod = methodSymbol.isVarArgs();
-    if (formalParams.size() != actualParams.size()
-        && !varArgsMethod
-        && !methodSymbol.isStatic()
-        && methodSymbol.isConstructor()
-        && methodSymbol.enclClass().isInner()) {
-      // In special cases like one in issue #366
-      // formal params and actual params do not match while using JDK11+
-      // we bail out in this particular case
-      return Description.NO_MATCH;
-    }
 
     // always do unboxing checks, whether or not the invoked method is annotated
     for (int i = 0; i < formalParams.size() && i < actualParams.size(); i++) {

nullaway/src/test/java/com/uber/nullaway/CoreTests.java

@@ -1134,4 +1134,24 @@ public void synchronizedInUnannotatedLambda() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void enclosingExpressionForNewClassTree() {
+    defaultCompilationHelper
+        .addSourceLines(
+            "Outer.java",
+            "package com.uber;",
+            "import org.jspecify.annotations.Nullable;",
+            "class Outer {",
+            "    class Inner {}",
+            "    static Inner testNegative(Outer outer) {",
+            "        return outer.new Inner() {};",
+            "    }",
+            "    static Inner testPositive(@Nullable Outer outer) {",
+            "        // BUG: Diagnostic contains: dereferenced expression outer is @Nullable",
+            "        return outer.new Inner() {};",
+            "    }",
+            "}")
+        .doTest();
+  }
 }