Add missing and double symbol checking to TreeChecker

TreeChecker now tests that a symbol does not have two definitions that define it,
and that every reference to a symbol owner by a term is in the scope of a definition
of that symbol.

Both tests fail on several files for pattern matcher.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/ast/tpd.scala b/src/dotty/tools/dotc/ast/tpd.scala
index 9b7c9cbae..4c21fcf49 100644
--- a/src/dotty/tools/dotc/ast/tpd.scala
+++ b/src/dotty/tools/dotc/ast/tpd.scala
@@ -9,6 +9,7 @@ import SymDenotations._, Symbols._, StdNames._, Annotations._, Trees._, Symbols.
 import Denotations._, Decorators._
 import config.Printers._
 import typer.Mode
+import collection.mutable
 import typer.ErrorReporting._
 
 import scala.annotation.tailrec
@@ -620,6 +621,12 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       }
       acc(false, tree)
     }
+
+    def filterSubTrees(f: Tree => Boolean): List[Tree] = {
+      val buf = new mutable.ListBuffer[Tree]
+      foreachSubTree { tree => if (f(tree)) buf += tree }
+      buf.toList
+    }
   }
 
   implicit class ListOfTreeDecorator(val xs: List[tpd.Tree]) extends AnyVal {