SI-6666 Restrict hidden `this` access in self/super calls.

Detect when classes (user authored or compiler generated)
local to a self or super constructor argument would require
premature access to the in-construction instance.

The same restriction applies for classes and objects; for objects,
the premature access would result in a null via MODULE$ field.

A residual error has been lodged as SI-6997.

I'd like to remove calls to `Symbol#outerClass` (which relies on
the flaky flag INCONSTRUCTOR, see my comments in the JIRA issue
for more discussion) from `LambdaLift` and `ExplicitOuter`, and
instead use the stack of active self/super calls to know when to
skip an enclosing class. That will obviate that flag.

1 files changed, 40 insertions, 0 deletions

diff --git a/test/files/neg/t6666.check b/test/files/neg/t6666.check
new file mode 100644
index 0000000000..d0378173ea
--- /dev/null
+++ b/test/files/neg/t6666.check
@@ -0,0 +1,40 @@
+t6666.scala:23: error: Implementation restriction: access of method x$2 in object O1 from anonymous class 2, would require illegal premature access to object O1
+  F.byname(x)
+           ^
+t6666.scala:30: error: Implementation restriction: access of value x$3 in object O2 from anonymous class 3, would require illegal premature access to object O2
+  F.byname(x)
+           ^
+t6666.scala:37: error: Implementation restriction: access of method x$4 in object O3 from anonymous class 4, would require illegal premature access to object O3
+  F.hof(() => x)
+              ^
+t6666.scala:50: error: Implementation restriction: access of method x$6 in class C1 from anonymous class 7, would require illegal premature access to the unconstructed `this` of class C1
+  F.byname(x)
+           ^
+t6666.scala:54: error: Implementation restriction: access of value x$7 in class C2 from anonymous class 8, would require illegal premature access to the unconstructed `this` of class C2
+  F.byname(x)
+           ^
+t6666.scala:58: error: Implementation restriction: access of method x$8 in class C3 from anonymous class 9, would require illegal premature access to the unconstructed `this` of class C3
+  F.hof(() => x)
+              ^
+t6666.scala:62: error: Implementation restriction: access of method x$9 in class C4 from object Nested$5, would require illegal premature access to the unconstructed `this` of class C4
+  object Nested { def xx = x}
+                           ^
+t6666.scala:68: error: Implementation restriction: access of method x$10 in class C5 from object Nested$6, would require illegal premature access to the unconstructed `this` of class C5
+    object Nested { def xx = x}
+                             ^
+t6666.scala:83: error: Implementation restriction: access of method x$12 in class C11 from anonymous class 12, would require illegal premature access to the unconstructed `this` of class C11
+      F.byname(x)
+               ^
+t6666.scala:102: error: Implementation restriction: access of method x$13 in class C13 from anonymous class 13, would require illegal premature access to the unconstructed `this` of class C13
+      F.hof(() => x)
+                  ^
+t6666.scala:111: error: Implementation restriction: access of method x$14 in class C14 from object Nested$7, would require illegal premature access to the unconstructed `this` of class C14
+      object Nested { def xx = x}
+                               ^
+t6666.scala:122: error: Implementation restriction: access of method x$15 in class C15 from object Nested$8, would require illegal premature access to the unconstructed `this` of class C15
+        object Nested { def xx = x}
+                                 ^
+t6666.scala:131: error: Implementation restriction: access of method foo$1 in class COuter from class CInner$1, would require illegal premature access to the unconstructed `this` of class COuter
+  class CInner extends C({foo})
+                          ^
+13 errors found