SI-6168 Retain prefix when parsing types in JVM signatures

When reading Java classfiles, the generic signatures are
used to construct the corresponding Scala type signatures.

In the enclosed test case, the field `SomeClass.f` had
the JVM signature:

    LContext<LSomeClass;>.Field<Ljava.lang.Integer;>;

The parser first (correctly) parsed the prefix as `Context[SomeClass]`.
It then looked up the type symbol for `Field` in that that type. It then
discarded the parsed prefix, and instead used the prefix from the
info of the type symbol: `Context[ParentType]`.

This commit changes the signature parser after the first `.` to
use the result of prior parsing as the prefix.

I've also included a test case with Java static inner classes,
which don't require any special treatment.

src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala

@@ -607,6 +607,8 @@ abstract class ClassfileParser {
       val sym     = getOwner(jflags).newValue(name.toTermName, NoPosition, sflags)
       val isEnum  = (jflags & JAVA_ACC_ENUM) != 0
 
+      // Note: the info may be overrwritten later with a generic signature
+      // parsed from SignatureATTR
       sym setInfo {
         if (isEnum) ConstantType(Constant(sym))
         else info
@@ -661,6 +663,8 @@ abstract class ClassfileParser {
               }
               info = MethodType(newParams, clazz.tpe)
           }
+        // Note: the info may be overrwritten later with a generic signature
+        // parsed from SignatureATTR
         sym.setInfo(info)
         importPrivateWithinFromJavaFlags(sym, jflags)
         parseAttributes(sym, info)
@@ -754,7 +758,9 @@ abstract class ClassfileParser {
             accept('.')
             val name = subName(c => c == ';' || c == '<' || c == '.').toTypeName
             val clazz = tpe.member(name)
-            tpe = processClassType(processInner(clazz.tpe))
+            val dummyArgs = Nil // the actual arguments are added in processClassType
+            val inner = typeRef(pre = tpe, sym = clazz, args = dummyArgs)
+            tpe = processClassType(inner)
           }
           accept(';')
           tpe

test/files/run/t6168/Context.java

@@ -0,0 +1,34 @@
+public class Context<ParentType> {
+    private ParentType parent;
+
+    public Context() {}
+
+    public ParentType getParent() {
+        return parent;
+    }
+
+    public void setParent(ParentType parent) {
+         this.parent = parent;
+    }
+
+    public Field<Integer> intField() {
+        return new Field<Integer>() {
+            @Override
+            public Integer get() {
+                return 0;
+            }
+
+            @Override
+            public ParentType set(Integer t) {
+                return parent;
+            }
+        };
+    }
+
+    public abstract class Field<T> { //Note this is a path dependent type
+
+        public abstract T get();
+
+        public abstract ParentType set(T t);
+    }
+}

test/files/run/t6168/JavaTest.java

@@ -0,0 +1,8 @@
+public class JavaTest {
+  public static void main(String[] args) {
+    SomeClass a = new SomeClass();
+    SomeClass2 a2 = new SomeClass2();
+    SomeClass b = a.f.set(23).f.set(23);
+    SomeClass2 b2 = a2.f.set(23).f.set(23);
+  }
+}

test/files/run/t6168/SomeClass.java

@@ -0,0 +1,14 @@
+public class SomeClass {
+    private final Context<SomeClass> context = new Context<SomeClass>();
+    {
+        context.setParent(this);
+    }
+
+    public final Context<SomeClass>.Field<Integer> f = context.intField();
+
+    public SomeClass() {
+        f.set(23).f.set(23);
+    }
+}
+
+

test/files/run/t6168/SomeClass2.java

@@ -0,0 +1,12 @@
+public class SomeClass2 {
+    private final Context<SomeClass2> context = new Context<SomeClass2>();
+    {
+        context.setParent(this);
+    }
+
+    public final Context<SomeClass2>.Field<Integer> f = context.intField();
+
+    public SomeClass2() {
+        f.set(23).f.set(23);
+    }
+}

test/files/run/t6168/main.scala

@@ -0,0 +1,15 @@
+
+
+object Test extends App {
+  JavaTest.main(null)
+
+  var a1 : SomeClass = new SomeClass
+  var a2 : SomeClass2 = new SomeClass2
+  //import language.implicitConversions
+  //implicit def setParentType2SomeClass(x:Any) = x.asInstanceOf[SomeClass]
+  //implicit def setParentType2SomeClass2(x:Any) = x.asInstanceOf[SomeClass2]
+  //var b : SomeClass = a.f.set(23).asInstanceOf[SomeClass].f.set(23).asInstanceOf[SomeClass]
+  //var b2 : SomeClass2 = a2.f.set(23).asInstanceOf[SomeClass2].f.set(23).asInstanceOf[SomeClass2]
+  var b1 : SomeClass =  a1.f.set(23).f.set(23)
+  var b2 : SomeClass2 = a2.f.set(23).f.set(23)
+}

test/files/run/t6168b/Context.java

@@ -0,0 +1,34 @@
+public class Context<ParentType> {
+    private ParentType parent;
+
+    public Context() {}
+
+    public ParentType getParent() {
+        return parent;
+    }
+
+    public void setParent(ParentType parent) {
+         this.parent = parent;
+    }
+
+    public Field<Integer> intField() {
+        return new Field<Integer>() {
+            @Override
+            public Integer get() {
+                return 0;
+            }
+
+            @Override
+            public ParentType set(Integer t) {
+                return parent;
+            }
+        };
+    }
+
+    public static abstract class Field<T> {
+
+        public abstract T get();
+
+        public abstract Object set(T t);
+    }
+}

test/files/run/t6168b/JavaTest.java

@@ -0,0 +1,6 @@
+public class JavaTest {
+  public static void main(String[] args) {
+    SomeClass a = new SomeClass();
+    Object b = a.f.set(23);
+  }
+}

test/files/run/t6168b/SomeClass.java

@@ -0,0 +1,11 @@
+public class SomeClass {
+    private final Context<SomeClass> context = new Context<SomeClass>();
+    {
+        context.setParent(this);
+    }
+
+    public final Context.Field<Integer> f = context.intField();
+
+}
+
+

test/files/run/t6168b/main.scala

@@ -0,0 +1,8 @@
+
+
+object Test extends App {
+  JavaTest.main(null)
+
+  var a1 : SomeClass = new SomeClass
+  var b1 : Object =  a1.f.set(23)
+}