Do not patch stdlib when compilingwith -Yscala2-stdlib

Author: nicolasstucki

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

@@ -1369,7 +1369,9 @@ class Definitions {
       denot.sourceModule.info = denot.typeRef // we run into a cyclic reference when patching if this line is omitted
       patch2(denot, patchCls)
 
-    if denot.name == tpnme.Predef.moduleClassName && denot.symbol == ScalaPredefModuleClass then
+    if ctx.settings.Yscala2Stdlib.value then
+      ()
+    else if denot.name == tpnme.Predef.moduleClassName && denot.symbol == ScalaPredefModuleClass then
       patchWith(ScalaPredefModuleClassPatch)
     else if denot.name == tpnme.language.moduleClassName && denot.symbol == LanguageModuleClass then
       patchWith(LanguageModuleClassPatch)

compiler/src/dotty/tools/dotc/transform/TreeChecker.scala

@@ -574,16 +574,11 @@ object TreeChecker {
 
       val symbolsNotDefined = (decls -- defined - constr.symbol).filterNot(isAllowed)
 
-      def isScala2LibBootstrappedIssue =
-        // TODO remove the need for this workaround
-        // Patched members should be added to they class to they definitions
-        ctx.settings.Yscala2Stdlib.value && (
-          cls == defn.ScalaPredefModuleClass // scala.runtime.stdLibPatches.Predef
-          || defn.isTupleClass(cls) // specialized members
-          || cls.ownersIterator.contains(defn.LanguageModuleClass) // duplications?
-        )
+      def isStdlibBootstrappedIssue =
+        // FIXME: specialized members of TupleN are failing. These should not exist.
+        ctx.settings.Yscala2Stdlib.value && defn.isTupleClass(cls)
 
-      assert(symbolsNotDefined.isEmpty || isScala2LibBootstrappedIssue,
+      assert(symbolsNotDefined.isEmpty || isStdlibBootstrappedIssue,
         i" $cls tree does not define members: ${symbolsNotDefined.toList}%, %\n" +
         i"expected: ${decls.toList}%, %\n" +
         i"defined: ${defined}%, %")

compiler/src/dotty/tools/dotc/transform/YCheckPositions.scala

@@ -25,8 +25,6 @@ class YCheckPositions extends Phase {
         val checker = new TreeTraverser {
           private var sources: List[SourceFile] = ctx.source :: Nil
           def traverse(tree: tpd.Tree)(using Context): Unit = {
-            if ctx.settings.Yscala2Stdlib.value && tree.source.toString == "library/src/scala/runtime/stdLibPatches/Predef.scala" then
-              return // FIXME: there is a conflict between the sources of scala.Predef and scala.runtime.stdLibPatches.Predef
 
             // Check current context is correct
             assert(ctx.source == sources.head)