tuned --- fewer warnings in scala3;

--- a/src/Pure/General/antiquote.scala	Fri Apr 08 15:56:14 2022 +0200
+++ b/src/Pure/General/antiquote.scala	Fri Apr 08 16:26:48 2022 +0200
@@ -44,7 +44,8 @@
   /* read */
 
   def read(input: CharSequence): List[Antiquote] = {
-    Parsers.parseAll(Parsers.rep(Parsers.antiquote), Scan.char_reader(input)) match {
+    val result = Parsers.parseAll(Parsers.rep(Parsers.antiquote), Scan.char_reader(input))
+    (result : @unchecked) match {
       case Parsers.Success(xs, _) => xs
       case Parsers.NoSuccess(_, next) =>
         error("Malformed quotation/antiquotation source" +

--- a/src/Pure/General/json.scala	Fri Apr 08 15:56:14 2022 +0200
+++ b/src/Pure/General/json.scala	Fri Apr 08 16:26:48 2022 +0200
@@ -145,7 +145,8 @@
 
     def parse(input: CharSequence, strict: Boolean): T = {
       val scanner = new Lexer.Scanner(Scan.char_reader(input))
-      phrase(if (strict) json_object | json_array else json_value)(scanner) match {
+      val result = phrase(if (strict) json_object | json_array else json_value)(scanner)
+      (result : @unchecked) match {
         case Success(json, _) => json
         case NoSuccess(_, next) => error("Malformed JSON input at " + next.pos)
       }

--- a/src/Pure/Isar/token.scala	Fri Apr 08 15:56:14 2022 +0200
+++ b/src/Pure/Isar/token.scala	Fri Apr 08 16:26:48 2022 +0200
@@ -140,7 +140,8 @@
     val toks = new mutable.ListBuffer[Token]
     var ctxt = context
     while (!in.atEnd) {
-      Parsers.parse(Parsers.token_line(keywords, ctxt), in) match {
+      val result = Parsers.parse(Parsers.token_line(keywords, ctxt), in)
+      (result : @unchecked) match {
         case Parsers.Success((x, c), rest) => toks += x; ctxt = c; in = rest
         case Parsers.NoSuccess(_, rest) =>
           error("Unexpected failure of tokenizing input:\n" + rest.source.toString)

--- a/src/Pure/ML/ml_lex.scala	Fri Apr 08 15:56:14 2022 +0200
+++ b/src/Pure/ML/ml_lex.scala	Fri Apr 08 16:26:48 2022 +0200
@@ -281,7 +281,8 @@
     val toks = new mutable.ListBuffer[Token]
     var ctxt = context
     while (!in.atEnd) {
-      Parsers.parse(Parsers.token_line(SML, ctxt), in) match {
+      val result = Parsers.parse(Parsers.token_line(SML, ctxt), in)
+      (result : @unchecked) match {
         case Parsers.Success((x, c), rest) => toks += x; ctxt = c; in = rest
         case Parsers.NoSuccess(_, rest) =>
           error("Unexpected failure of tokenizing input:\n" + rest.source.toString)

--- a/src/Pure/Thy/bibtex.scala	Fri Apr 08 15:56:14 2022 +0200
+++ b/src/Pure/Thy/bibtex.scala	Fri Apr 08 16:26:48 2022 +0200
@@ -599,7 +599,8 @@
     val chunks = new mutable.ListBuffer[Chunk]
     var ctxt = context
     while (!in.atEnd) {
-      Parsers.parse(Parsers.chunk_line(ctxt), in) match {
+      val result = Parsers.parse(Parsers.chunk_line(ctxt), in)
+      (result : @unchecked) match {
         case Parsers.Success((x, c), rest) => chunks += x; ctxt = c; in = rest
         case Parsers.NoSuccess(_, rest) =>
           error("Unepected failure to parse input:\n" + rest.source.toString)