Add a THROW node to TASTY

Previously, we pickled references to the magic method
<special-ops>.throw which is compiler-specific.

Author: smarter

compiler/src/dotty/tools/dotc/core/tasty/TastyFormat.scala

@@ -77,6 +77,7 @@ Standard-Section: "ASTs" TopLevelStat*
                   SELECT                possiblySigned_NameRef qual_Term
                   QUALTHIS              typeIdent_Tree
                   NEW                   clsType_Term
+                  THROW                 throwableExpr_Term
                   NAMEDARG              paramName_NameRef arg_Term
                   APPLY          Length fn_Term arg_Term*
                   TYPEAPPLY      Length fn_Term arg_Type*
@@ -225,7 +226,7 @@ Standard Section: "Positions" Assoc*
 object TastyFormat {
 
   final val header = Array(0x5C, 0xA1, 0xAB, 0x1F)
-  val MajorVersion = 6
+  val MajorVersion = 7
   val MinorVersion = 0
 
   /** Tags used to serialize names */
@@ -332,12 +333,13 @@ object TastyFormat {
   final val BYNAMEtype = 84
   final val BYNAMEtpt = 85
   final val NEW = 86
-  final val IMPLICITarg = 87
-  final val PRIVATEqualified = 88
-  final val PROTECTEDqualified = 89
-  final val RECtype = 90
-  final val TYPEALIAS = 91
-  final val SINGLETONtpt = 92
+  final val THROW = 87
+  final val IMPLICITarg = 88
+  final val PRIVATEqualified = 89
+  final val PROTECTEDqualified = 90
+  final val RECtype = 91
+  final val TYPEALIAS = 92
+  final val SINGLETONtpt = 93
 
   // Cat. 4:    tag Nat AST
 
@@ -560,6 +562,7 @@ object TastyFormat {
     case APPLY => "APPLY"
     case TYPEAPPLY => "TYPEAPPLY"
     case NEW => "NEW"
+    case THROW => "THROW"
     case TYPED => "TYPED"
     case NAMEDARG => "NAMEDARG"
     case ASSIGN => "ASSIGN"

compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala

@@ -361,10 +361,15 @@ class TreePickler(pickler: TastyPickler) {
               pickleTree(qual)
           }
         case Apply(fun, args) =>
-          writeByte(APPLY)
-          withLength {
-            pickleTree(fun)
-            args.foreach(pickleTree)
+          if (fun.symbol eq defn.throwMethod) {
+            writeByte(THROW)
+            pickleTree(args.head)
+          } else {
+            writeByte(APPLY)
+            withLength {
+              pickleTree(fun)
+              args.foreach(pickleTree)
+            }
           }
         case TypeApply(fun, args) =>
           writeByte(TYPEAPPLY)

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -974,6 +974,8 @@ class TreeUnpickler(reader: TastyReader,
           untpd.This(qual).withType(ThisType.raw(tref))
         case NEW =>
           New(readTpt())
+        case THROW =>
+          Throw(readTerm())
         case SINGLETONtpt =>
           SingletonTypeTree(readTerm())
         case BYNAMEtpt =>

tests/pos/tasty/definitions.scala

@@ -73,6 +73,7 @@ object definitions {
     case Literal(value: Constant)
     case This(id: Option[Id])
     case New(tpt: TypeTree)
+    case Throw(expr: Term)
     case NamedArg(name: TermName, arg: Term)
     case Apply(fn: Term, args: List[Term])
     case TypeApply(fn: Term, args: List[TypeTree])