Re-constant-fold when rechecking

This is necessary since not all constant folded terms are converted to literals. The conversion does not happen if one of the operands is impure. A test case is run/final-field.scala

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

@@ -13,6 +13,7 @@ import NullOpsDecorator.stripNull
 import typer.ErrorReporting.err
 import typer.ProtoTypes.*
 import typer.TypeAssigner.seqLitType
+import typer.ConstFold
 import config.Printers.recheckr
 import util.Property
 import StdNames.nme
@@ -70,6 +71,11 @@ abstract class Recheck extends Phase, IdentityDenotTransformer:
  sym.updateInfo(reinferResult(sym.info))
  case _ =>
 
+ def constFold(tree: Tree, tp: Type)(using Context): Type =
+ val tree1 = tree.withType(tp)
+ val tree2 = ConstFold(tree1)
+ if tree2 ne tree1 then tree2.tpe else tp
+
  def recheckIdent(tree: Ident)(using Context): Type =
  tree.tpe
 
@@ -83,7 +89,7 @@ abstract class Recheck extends Phase, IdentityDenotTransformer:
  val mbr = qualType.findMember(name, qualType,
  excluded = if tree.symbol.is(Private) then EmptyFlags else Private
  ).suchThat(tree.symbol ==)
- qualType.select(name, mbr)
+ constFold(tree, qualType.select(name, mbr))
 
  def recheckBind(tree: Bind, pt: Type)(using Context): Type = tree match
  case Bind(name, body) =>
@@ -147,14 +153,14 @@ abstract class Recheck extends Phase, IdentityDenotTransformer:
  assert(formals.isEmpty)
  Nil
  val argTypes = recheckArgs(tree.args, formals, fntpe.paramRefs)
- fntpe.instantiate(argTypes)
+ constFold(tree, fntpe.instantiate(argTypes))
 
  def recheckTypeApply(tree: TypeApply, pt: Type)(using Context): Type =
  recheck(tree.fun).widen match
  case fntpe: PolyType =>
  assert(sameLength(fntpe.paramInfos, tree.args))
  val argTypes = tree.args.map(recheck(_))
- fntpe.instantiate(argTypes)
+ constFold(tree, fntpe.instantiate(argTypes))
 
  def recheckTyped(tree: Typed)(using Context): Type =
  val tptType = recheck(tree.tpt)