compiler: enhance Normalize.insertSuperCtor to consider inherited cto…

…r visibility

Previously when selecting implicit chained super ctor, we short circuited if
we found more than one constructor in superclass.  With this change we now
filter out those constructors that aren't visible.  For example if a superclass
in another pod has both a public make and an internal makeFoo, we will now
implicitly bind the ctor chain to the public make instead of raising an error
in CheckErrors.

src/compiler/fan/namespace/CSlot.fan

@@ -78,6 +78,18 @@ mixin CSlot
   **
   abstract CBridge? usesBridge()
 
+  **
+  ** Return if this slot is visible to the given type
+  **
+  Bool isVisibleTo(CType curType)
+  {
+    if (parent == curType) return true
+    if (isPrivate) return false
+    if (isInternal) return parent.pod == curType.pod
+    if (isProtected) return parent.pod == curType.pod || curType.fits(parent)
+    return true
+  }
+
 }
 
 **************************************************************************

src/compiler/fan/steps/Normalize.fan

@@ -154,9 +154,14 @@ class Normalize : CompilerStep
     if (parent.isMixin) return
     if (base.isObj) return
 
-    // check if the base class has exactly one available
+    // check if the base class has exactly one available, visible
     // constructor with no parameters
     superCtors := base.instanceCtors
+    if (superCtors.size > 1)
+    {
+      // if there are more than one, then only find ctors visible to me
+      superCtors = superCtors.findAll |ctor| { ctor.isVisibleTo(curType) }
+    }
     if (superCtors.size != 1) return
     superCtor := superCtors.first
     if (superCtor.isPrivate) return

src/testCompiler/fan/MiscTest.fan

@@ -46,6 +46,30 @@ class MiscTest : CompilerTest
        ])
   }
 
+
+//////////////////////////////////////////////////////////////////////////
+// Normalize Ctor Visibility
+//////////////////////////////////////////////////////////////////////////
+
+  Void testCtorVisibility()
+  {
+    compile(
+     "class A
+      {
+        Int x
+        new make() { x = 10 }
+        private new makeAlt() { x = 20 }
+      }
+
+      class B : A {}
+      ")
+
+     t := pod.types[1]
+     b := t.make
+     verifyEq(t.name, "B")
+     verifyEq(b->x, 10)
+  }
+
 //////////////////////////////////////////////////////////////////////////
 // Normalize
 //////////////////////////////////////////////////////////////////////////