Fix #3597 - Don't check inline for params after pickling

There was a discrepancy in that value parameters had a Deferred flag set
before pickling but not after unpickling. This triggered a check that the
(missing) rhs of an inline parameter was a constant. This commit changes
the condition of the test to also exclude parameters. It also aligns
frontend and unpickler in that the frontend will no longer mark term
parameters as Deferred.

Author: odersky

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

@@ -264,7 +264,7 @@ trait UntypedTreeInfo extends TreeInfo[Untyped] { self: Trees.Instance[Untyped]
    */
   def lacksDefinition(mdef: MemberDef)(implicit ctx: Context) = mdef match {
     case mdef: ValOrDefDef =>
-      mdef.unforcedRhs == EmptyTree && !mdef.name.isConstructorName && !mdef.mods.is(ParamAccessor)
+      mdef.unforcedRhs == EmptyTree && !mdef.name.isConstructorName && !mdef.mods.is(TermParamOrAccessor)
     case mdef: TypeDef =>
       def isBounds(rhs: Tree): Boolean = rhs match {
         case _: TypeBoundsTree => true

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

@@ -575,7 +575,7 @@ object Flags {
   final val SyntheticOrPrivate = Synthetic | Private
 
   /** A deferred member or a parameter accessor (these don't have right hand sides) */
-  final val DeferredOrParamAccessor = Deferred | ParamAccessor
+  final val DeferredOrParamOrAccessor = Deferred | Param | ParamAccessor
 
   /** value that's final or inline */
   final val FinalOrInline = Final | Inline

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -1300,7 +1300,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
       case rhs => typedExpr(rhs, tpt1.tpe)
     }
     val vdef1 = assignType(cpy.ValDef(vdef)(name, tpt1, rhs1), sym)
-    if (sym.is(Inline, butNot = DeferredOrParamAccessor))
+    if (sym.is(Inline, butNot = DeferredOrParamOrAccessor))
       checkInlineConformant(rhs1, em"right-hand side of inline $sym")
     patchIfLazy(vdef1)
     patchFinalVals(vdef1)

tests/pos-from-tasty/i3597.scala

@@ -0,0 +1,3 @@
+object Test {
+  def bar(inline n: Int) = n
+}