Realizability refactoring

Distinguish between isStable and isRealizable.
Issue migration warnings for realizibility failures.
Provide error diagnostics why something is not realizable.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index c94c90d1d..79035108e 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -308,7 +308,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
   def typedSelect(tree: untpd.Select, pt: Type)(implicit ctx: Context): Tree = track("typedSelect") {
     def asSelect(implicit ctx: Context): Tree = {
       val qual1 = typedExpr(tree.qualifier, selectionProto(tree.name, pt, this))
-      if (tree.name.isTypeName) checkStable(qual1.tpe, qual1.pos)
+      if (tree.name.isTypeName) checkStableAndRealizable(qual1.tpe, qual1.pos)
       typedSelect(tree, pt, qual1)
    }
 
@@ -342,6 +342,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
 
   def typedSelectFromTypeTree(tree: untpd.SelectFromTypeTree, pt: Type)(implicit ctx: Context): Tree = track("typedSelectFromTypeTree") {
     val qual1 = typedType(tree.qualifier, selectionProto(tree.name, pt, this))
+    //checkRealizable(qual1.tpe, qual1.pos)
     assignType(cpy.SelectFromTypeTree(tree)(qual1, tree.name), qual1)
   }
 
@@ -822,7 +823,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
 
   def typedSingletonTypeTree(tree: untpd.SingletonTypeTree)(implicit ctx: Context): SingletonTypeTree = track("typedSingletonTypeTree") {
     val ref1 = typedExpr(tree.ref)
-    checkStable(ref1.tpe, tree.pos)
+    checkStableAndRealizable(ref1.tpe, tree.pos)
     assignType(cpy.SingletonTypeTree(tree)(ref1), ref1)
   }
 
@@ -1056,7 +1057,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
 
   def typedImport(imp: untpd.Import, sym: Symbol)(implicit ctx: Context): Import = track("typedImport") {
     val expr1 = typedExpr(imp.expr, AnySelectionProto)
-    checkStable(expr1.tpe, imp.expr.pos)
+    checkStableAndRealizable(expr1.tpe, imp.expr.pos)
     assignType(cpy.Import(imp)(expr1, imp.selectors), sym)
   }