Fix chekc.

Author: adampauls

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -881,7 +881,8 @@ object Parsers {
       val next = in.lookahead.token
       next == LBRACKET || next == LPAREN
 
-    /** Is current ident a `*`, and is it followed by a `)` or `, )`? */
+    /** Is current ident a `*`, and is it followed by a `)`, `, )`, `,EOF`? The latter two are not
+        syntactically valid, but we need to include them here for error recovery. */
     def followingIsVararg(): Boolean =
       in.isIdent(nme.raw.STAR) && {
         val lookahead = in.LookaheadScanner()
@@ -890,7 +891,7 @@ object Parsers {
         || lookahead.token == COMMA
            && {
              lookahead.nextToken()
-             lookahead.token == RPAREN
+             lookahead.token == RPAREN || lookahead.token == EOF
            }
       }
 

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -659,8 +659,6 @@ object Scanners {
                  && (token == RPAREN || token == RBRACKET || token == RBRACE || token == OUTDENT)
               then
                 () /* skip the trailing comma */
-              else if token == EOF then // e.g. when the REPL is parsing "val List(x, y, _*,"
-                () /* skip the trailing comma */
               else
                 reset()
         case END =>

compiler/src/dotty/tools/dotc/parsing/Tokens.scala

@@ -285,7 +285,7 @@ object Tokens extends TokensCommon {
 
   final val endMarkerTokens = identifierTokens | BitSet(IF, WHILE, FOR, MATCH, TRY, NEW, THROW, GIVEN, VAL, THIS)
 
-  final val skipStopTokens = BitSet(SEMI, NEWLINE, NEWLINES, RBRACE, RPAREN, RBRACKET, OUTDENT)
+  final val skipStopTokens = BitSet(SEMI, NEWLINE, NEWLINES, RBRACE, RPAREN, RBRACKET, OUTDENT, COMMA)
 
   final val softModifierNames = Set(nme.inline, nme.opaque, nme.open, nme.transparent, nme.infix)
 }

compiler/src/dotty/tools/repl/Main.scala

@@ -1,6 +1,7 @@
 package dotty.tools.repl
 
 /** Main entry point to the REPL */
+// To test, run bin/scala
 object Main {
   def main(args: Array[String]): Unit =
     new ReplDriver(args).tryRunning

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -825,7 +825,11 @@ trait ParallelTesting extends RunnerOrchestration { self =>
       def sawDiagnostic(d: Diagnostic): Unit =
         d.pos.nonInlined match
           case srcpos if srcpos.exists =>
-            val key = s"${relativize(srcpos.source.file.toString)}:${srcpos.line + 1}"
+            // If an annotated // error is placed on the last line of the file, EOF errors can show up past the last.
+            // Without this adjustment, it's not possible to annotate // error on errors whose position is EOF
+            // in some cases.
+            val adjustedLine = if srcpos.point == srcpos.source.length && srcpos.point > 0 then srcpos.source.offsetToLine(srcpos.point - 1) else srcpos.line
+            val key = s"${relativize(srcpos.source.file.toString)}:${adjustedLine + 1}"
             if !seenAt(key) then unexpected += key
           case srcpos =>
             if !seenAt("nopos") then unpositioned += relativize(srcpos.source.file.toString)

tests/neg/arg-eof.scala

@@ -0,0 +1,3 @@
+object Test:
+  case class Widget(name: String, other: Int = 5)
+  Widget(name = "foo", // error // error

tests/neg/i1679.scala

@@ -1,5 +1,5 @@
 class A[T]
 object o {
   // Testing compiler crash, this test should be modified when named type argument are completely implemented
-  val x: A[T=Int, T=Int] = ??? // error: ']' expected, but '=' found
+  val x: A[T=Int, T=Int] = ??? // error: ']' expected, but '=' found // error
 }

tests/neg/t1625.scala

@@ -1,3 +1,3 @@
 trait T3 {
-  def foo(x: String*, y: String*, c: String*): Int // error: an identifier expected, but ',' found
-}
+  def foo(x: String*, y: String*, c: String*): Int // error: an identifier expected, but ',' found // error: an identifier expected, but ',' found
+}

tests/neg/trailing-comma-pattern.check

@@ -0,0 +1,6 @@
+-- [E032] Syntax Error: tests/neg/trailing-comma-pattern.scala:4:0 -----------------------------------------------------
+4 |
+  |^
+  |pattern expected
+
+longer explanation available when compiling with `-explain`

tests/neg/trailing-comma-pattern.scala

@@ -0,0 +1,3 @@
+object Test:
+  val List(x, y, _*,
+// error