8334258: Compiler erronousely allows access to instance variable in argument expression of a constructor invocation

Reviewed-by: mcimadamore

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -100,6 +100,7 @@ public class Resolve {
     DeferredAttr deferredAttr;
     Check chk;
     Infer infer;
+    Preview preview;
     ClassFinder finder;
     ModuleFinder moduleFinder;
     Types types;
@@ -135,7 +136,7 @@ public class Resolve {
         moduleFinder = ModuleFinder.instance(context);
         types = Types.instance(context);
         diags = JCDiagnostic.Factory.instance(context);
-        Preview preview = Preview.instance(context);
+        preview = Preview.instance(context);
         Source source = Source.instance(context);
         Options options = Options.instance(context);
         compactMethodDiags = options.isSet(Option.XDIAGS, "compact") ||
@@ -1480,10 +1481,11 @@ public class Resolve {
 
     /** Find unqualified variable or field with given name.
      *  Synthetic fields always skipped.
+     *  @param pos       The position to use for error reporting.
      *  @param env     The current environment.
      *  @param name    The name of the variable or field.
      */
-    Symbol findVar(Env<AttrContext> env, Name name) {
+    Symbol findVar(DiagnosticPosition pos, Env<AttrContext> env, Name name) {
         Symbol bestSoFar = varNotFound;
         Env<AttrContext> env1 = env;
         boolean staticOnly = false;
@@ -1508,7 +1510,7 @@ public class Resolve {
                         (sym.flags() & STATIC) == 0) {
                     if (staticOnly)
                         return new StaticError(sym);
-                    if (env1.info.ctorPrologue && !isAllowedEarlyReference(env1, (VarSymbol)sym))
+                    if (env1.info.ctorPrologue && !isAllowedEarlyReference(pos, env1, (VarSymbol)sym))
                         return new RefBeforeCtorCalledError(sym);
                 }
                 return sym;
@@ -2421,15 +2423,15 @@ public class Resolve {
      *                   (a subset of VAL, TYP, PCK).
      */
     Symbol findIdent(DiagnosticPosition pos, Env<AttrContext> env, Name name, KindSelector kind) {
-        return checkNonExistentType(checkRestrictedType(pos, findIdentInternal(env, name, kind), name));
+        return checkNonExistentType(checkRestrictedType(pos, findIdentInternal(pos, env, name, kind), name));
     }
 
-    Symbol findIdentInternal(Env<AttrContext> env, Name name, KindSelector kind) {
+    Symbol findIdentInternal(DiagnosticPosition pos, Env<AttrContext> env, Name name, KindSelector kind) {
         Symbol bestSoFar = typeNotFound;
         Symbol sym;
 
         if (kind.contains(KindSelector.VAL)) {
-            sym = findVar(env, name);
+            sym = findVar(pos, env, name);
             if (sym.exists()) return sym;
             else bestSoFar = bestOf(bestSoFar, sym);
         }
@@ -3776,7 +3778,7 @@ public class Resolve {
                 if (sym != null) {
                     if (staticOnly)
                         sym = new StaticError(sym);
-                    else if (env1.info.ctorPrologue && !isAllowedEarlyReference(env1, (VarSymbol)sym))
+                    else if (env1.info.ctorPrologue && !isAllowedEarlyReference(pos, env1, (VarSymbol)sym))
                         sym = new RefBeforeCtorCalledError(sym);
                     return accessBase(sym, pos, env.enclClass.sym.type,
                                   name, true);
@@ -3845,7 +3847,7 @@ public class Resolve {
      * We also don't verify that the field has no initializer, which is required.
      * To catch those cases, we rely on similar logic in Attr.checkAssignable().
      */
-    private boolean isAllowedEarlyReference(Env<AttrContext> env, VarSymbol v) {
+    private boolean isAllowedEarlyReference(DiagnosticPosition pos, Env<AttrContext> env, VarSymbol v) {
 
         // Check assumptions
         Assert.check(env.info.ctorPrologue);
@@ -3880,6 +3882,9 @@ public class Resolve {
         if (isEarlyReference(env, base, v) && v.owner != env.enclClass.sym)
             return false;
 
+        // The flexible constructors feature must be enabled
+        preview.checkSourceLevel(pos, Feature.FLEXIBLE_CONSTRUCTORS);
+
         // OK
         return true;
     }

test/langtools/tools/javac/SuperInit/EarlyAssignmentNoPreview1.java

@@ -0,0 +1,21 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8334258
+ * @summary Disallow early assignment if FLEXIBLE_CONSTRUCTORS preview feature is not enabled
+ * @compile/fail/ref=EarlyAssignmentNoPreview1.out -XDrawDiagnostics EarlyAssignmentNoPreview1.java
+ */
+public class EarlyAssignmentNoPreview1 {
+
+    Runnable r;
+
+    public EarlyAssignmentNoPreview1() {
+        this(r = () -> System.out.println("hello"));
+    }
+
+    public EarlyAssignmentNoPreview1(Runnable r) {
+    }
+
+    public static void main(String[] args) {
+        new EarlyAssignmentNoPreview1();
+    }
+}

test/langtools/tools/javac/SuperInit/EarlyAssignmentNoPreview1.out

@@ -0,0 +1,2 @@
+EarlyAssignmentNoPreview1.java:12:14: compiler.err.preview.feature.disabled: (compiler.misc.feature.flexible.constructors)
+1 error

test/langtools/tools/javac/SuperInit/EarlyAssignmentNoPreview2.java

@@ -0,0 +1,21 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8334258
+ * @summary Disallow early assignment if FLEXIBLE_CONSTRUCTORS preview feature is not enabled
+ * @compile/fail/ref=EarlyAssignmentNoPreview2.out -XDrawDiagnostics EarlyAssignmentNoPreview2.java
+ */
+public class EarlyAssignmentNoPreview2 {
+
+    Runnable r;
+
+    public EarlyAssignmentNoPreview2() {
+        this(this.r = () -> System.out.println("hello"));
+    }
+
+    public EarlyAssignmentNoPreview2(Runnable r) {
+    }
+
+    public static void main(String[] args) {
+        new EarlyAssignmentNoPreview2();
+    }
+}

test/langtools/tools/javac/SuperInit/EarlyAssignmentNoPreview2.out

@@ -0,0 +1,2 @@
+EarlyAssignmentNoPreview2.java:12:14: compiler.err.preview.feature.disabled: (compiler.misc.feature.flexible.constructors)
+1 error

test/langtools/tools/javac/SuperInit/EarlyAssignmentNoPreview3.java

@@ -0,0 +1,21 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8334258
+ * @summary Disallow early assignment if FLEXIBLE_CONSTRUCTORS preview feature is not enabled
+ * @compile/fail/ref=EarlyAssignmentNoPreview3.out -XDrawDiagnostics EarlyAssignmentNoPreview3.java
+ */
+public class EarlyAssignmentNoPreview3 {
+
+    Runnable r;
+
+    public EarlyAssignmentNoPreview3() {
+        this(EarlyAssignmentNoPreview3.this.r = () -> System.out.println("hello"));
+    }
+
+    public EarlyAssignmentNoPreview3(Runnable r) {
+    }
+
+    public static void main(String[] args) {
+        new EarlyAssignmentNoPreview3();
+    }
+}

test/langtools/tools/javac/SuperInit/EarlyAssignmentNoPreview3.out

@@ -0,0 +1,2 @@
+EarlyAssignmentNoPreview3.java:12:39: compiler.err.preview.feature.disabled: (compiler.misc.feature.flexible.constructors)
+1 error