Revert "Rename InlineCopier to ConservativeTreeCopier, use it in TypeMaps"

This reverts commit bb63e31.

Author: mbovel

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -842,14 +842,6 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       Closure(tree: Tree)(env, meth, tpt)
   }
 
-  // This is a more fault-tolerant copier that does not cause errors when
-  // function types in applications are undefined.
-  // This was called `Inliner.InlineCopier` before 3.6.3.
-  class ConservativeTreeCopier() extends TypedTreeCopier:
-    override def Apply(tree: Tree)(fun: Tree, args: List[Tree])(using Context): Apply =
-      if fun.tpe.widen.exists then super.Apply(tree)(fun, args)
-      else untpd.cpy.Apply(tree)(fun, args).withTypeUnchecked(tree.tpe)
-
   override def skipTransform(tree: Tree)(using Context): Boolean = tree.tpe.isError
 
   implicit class TreeOps[ThisTree <: tpd.Tree](private val tree: ThisTree) extends AnyVal {

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -6310,14 +6310,7 @@ object Types extends TypeUtils {
       }
     }
 
-    private def treeTypeMap = new TreeTypeMap(
-      typeMap = this,
-      // Using `ConservativeTreeCopier` is needed when copying dependent annoted
-      // types, where we can refer to a previous parameter represented as
-      // `TermParamRef` that has no underlying type yet.
-      // See tests/pos/annot-17242.scala.
-      cpy = ConservativeTreeCopier()
-    )
+    private def treeTypeMap = new TreeTypeMap(typeMap = this)
 
     def mapOver(syms: List[Symbol]): List[Symbol] = mapSymbols(syms, treeTypeMap)
 

compiler/src/dotty/tools/dotc/inlines/Inliner.scala

@@ -96,6 +96,15 @@ object Inliner:
     }
   end isElideableExpr
 
+  // InlineCopier is a more fault-tolerant copier that does not cause errors when
+  // function types in applications are undefined. This is necessary since we copy at
+  // the same time as establishing the proper context in which the copied tree should
+  // be evaluated. This matters for opaque types, see neg/i14653.scala.
+  private class InlineCopier() extends TypedTreeCopier:
+    override def Apply(tree: Tree)(fun: Tree, args: List[Tree])(using Context): Apply =
+      if fun.tpe.widen.exists then super.Apply(tree)(fun, args)
+      else untpd.cpy.Apply(tree)(fun, args).withTypeUnchecked(tree.tpe)
+
   // InlinerMap is a TreeTypeMap with special treatment for inlined arguments:
   // They are generally left alone (not mapped further, and if they wrap a type
   // the type Inlined wrapper gets dropped.
@@ -108,13 +117,7 @@ object Inliner:
       substFrom: List[Symbol],
       substTo: List[Symbol])(using Context)
     extends TreeTypeMap(
-      typeMap, treeMap, oldOwners, newOwners, substFrom, substTo,
-      // It is necessary to use the `ConservativeTreeCopier` since we copy at
-      // the same time as establishing the proper context in which the copied
-      // tree should be evaluated. This matters for opaque types, see
-      // neg/i14653.scala.
-      ConservativeTreeCopier()
-    ):
+      typeMap, treeMap, oldOwners, newOwners, substFrom, substTo, InlineCopier()):
 
     override def transform(tree: Tree)(using Context): Tree =
       tree match