JDK 8148716: Variable proxy duplicate

[B. Blaser]

Hi,

2017-02-09 2:00 GMT+01:00 Maurizio Cimadamore <maurizio.cimadamore at oracle.com>:
> Hi,
> I believe that to be a duplicate of
>
> https://bugs.openjdk.java.net/browse/JDK-8169345
>
> for which we have a fix in the works which we'll push to 10 soon.
>
> Srikanth and I decided to go for a more radical rewriting in the area,
> making a lot of the logic in the code (now implicit in the use of the Scope
> data structure) more explicit and less prone to errors of this sort.
>
> Thanks
> Maurizio

As this problem seems to be present since jdk6 (issue 8169345 you
pointed me to), it would perhaps be interesting to have a temporary
fix which could be eventually backported, or at least corrected in
jdk9.

To make things more explicit and to have a quite safer patch, I can
suggest to incorporate the name of the variable's owner to the proxy
name, as below. The rewriting you are working on is probably better,
but the following fix could perhaps make things work until jdk10...?

What's your opinion on that?

Thanks,
Bernard

diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
@@ -308,7 +308,7 @@
             Symbol sym = _sym;
             if (sym.kind == VAR || sym.kind == MTH) {
                 while (sym != null && sym.owner != owner)
-                    sym = proxies.findFirst(proxyName(sym.name));
+                    sym = proxies.findFirst(proxyName(sym));
                 if (sym != null && sym.owner == owner) {
                     VarSymbol v = (VarSymbol)sym;
                     if (v.getConstValue() == null) {
@@ -1095,7 +1095,7 @@
                 return makeLit(sym.type, cv);
             }
             // Otherwise replace the variable by its proxy.
-            sym = proxies.findFirst(proxyName(sym.name));
+            sym = proxies.findFirst(proxyName(sym));
             Assert.check(sym != null && (sym.flags_field & FINAL) != 0);
             tree = make.at(tree.pos).Ident(sym);
         }
@@ -1394,8 +1394,12 @@

     /** The name of a free variable proxy.
      */
-    Name proxyName(Name name) {
-        return names.fromString("val" + target.syntheticNameChar() + name);
+    Name proxyName(Symbol s) {
+        String sep = target.syntheticNameChar() + "";
+        if (s.owner != null && s.owner.name != null)
+            sep = sep + s.owner.name + sep;
+
+        return names.fromString("val" + sep + s.name);
     }

     /** Proxy definitions for all free variables in given list, in
reverse order.
@@ -1414,7 +1418,7 @@
         for (List<VarSymbol> l = freevars; l.nonEmpty(); l = l.tail) {
             VarSymbol v = l.head;
             VarSymbol proxy = new VarSymbol(
-                flags, proxyName(v.name), v.erasure(types), owner);
+                flags, proxyName(v), v.erasure(types), owner);
             proxies.enter(proxy);
             JCVariableDecl vd = make.at(pos).VarDef(proxy, null);
             vd.vartype = access(vd.vartype);
@@ -2717,7 +2721,7 @@
             if (fvs.nonEmpty()) {
                 List<Type> addedargtypes = List.nil();
                 for (List<VarSymbol> l = fvs; l.nonEmpty(); l = l.tail) {
-                    final Name pName = proxyName(l.head.name);
+                    final Name pName = proxyName(l.head);
                     m.capturedLocals =
                         m.capturedLocals.prepend((VarSymbol)
                                                 (proxies.findFirst(pName)));