Improve parsing error message

Author: nicolasstucki

library/src/scala/annotation/newMain.scala

@@ -314,23 +314,23 @@ final class newMain extends MainAnnotation[FromString, Any]:
     }
   end explain
 
-  private def convert[T](argName: String, arg: String, p: FromString[T]): () => T =
-    p.fromStringOption(arg) match
-      case Some(t) => () => t
-      case None => error(s"invalid argument for $argName: $arg")
-
   def argGetter[T](param: Parameter, arg: String, defaultArgument: Option[() => T])(using p: FromString[T]): () => T = {
-    if arg.nonEmpty then convert(param.name, arg, p)
+    if arg.nonEmpty then parse[T](param, arg)
     else defaultArgument match
       case Some(defaultGetter) => defaultGetter
       case None => error(s"missing argument for ${param.name}")
   }
 
   def varargGetter[T](param: Parameter, args: Seq[String])(using p: FromString[T]): () => Seq[T] = {
-    val getters = args.map(arg => convert(param.name, arg, p))
+    val getters = args.map(arg => parse[T](param, arg))
     () => getters.map(_())
   }
 
+  private def parse[T](param: Parameter, arg: String)(using p: FromString[T]): () => T =
+    p.fromStringOption(arg) match
+      case Some(t) => () => t
+      case None => error(s"could not parse argument for `${param.name}` of type ${param.typeName.split('.').last}: $arg")
+
   def run(execProgram: () => Any): Unit = {
     if errors.nonEmpty then
       for msg <- errors do println(s"Error: $msg")

tests/run/main-annotation-help-override.check

@@ -4,7 +4,7 @@ Usage: helpOverride1 [--notHelp] <Int>
 A method that should let --help and -h display help.
 Arguments:
   --notHelp - Int
-Error: invalid argument for help: --help
+Error: could not parse argument for `help` of type Int: --help
 Usage: helpOverride2 [--help] <Int>
 Usage: helpOverride3 [-h] <Int>
 
@@ -13,7 +13,7 @@ Arguments:
   -h - Int
 Error: missing argument for h
 Usage: helpOverride4 [--help] <Int> [-h] <Int>
-Error: invalid argument for notHelp: --help
+Error: could not parse argument for `notHelp` of type Int: --help
 Usage: helpOverride5 [--notHelp | --help] <Int>
 Usage: helpOverride6 [--notHelp | -h] <Int>
 
@@ -22,7 +22,7 @@ Arguments:
   --notHelp (-h) - Int
 Error: missing argument for notH
 Usage: helpOverride7 [--notHelp | --help] <Int> [--notH | -h] <Int>
-Error: invalid argument for notHelp: --help
+Error: could not parse argument for `notHelp` of type Int: --help
 Usage: helpOverride8 [--notHelp | --help | -h] <Int>
 ##### -h
 Usage: helpOverride1 [--notHelp] <Int>
@@ -35,7 +35,7 @@ Usage: helpOverride2 [--help] <Int>
 A method that should let -h display help, but not --help.
 Arguments:
   --help - Int
-Error: invalid argument for h: -h
+Error: could not parse argument for `h` of type Int: -h
 Usage: helpOverride3 [-h] <Int>
 Error: missing argument for h
 Usage: helpOverride4 [--help] <Int> [-h] <Int>
@@ -44,9 +44,9 @@ Usage: helpOverride5 [--notHelp | --help] <Int>
 A method that should let -h display help, but not --help.
 Arguments:
   --notHelp (--help) - Int
-Error: invalid argument for notHelp: -h
+Error: could not parse argument for `notHelp` of type Int: -h
 Usage: helpOverride6 [--notHelp | -h] <Int>
 Error: missing argument for notH
 Usage: helpOverride7 [--notHelp | --help] <Int> [--notH | -h] <Int>
-Error: invalid argument for notHelp: -h
+Error: could not parse argument for `notHelp` of type Int: -h
 Usage: helpOverride8 [--notHelp | --help | -h] <Int>

tests/run/main-annotation-wrong-param-type.check

@@ -1,14 +1,14 @@
-Error: invalid argument for inc: true
+Error: could not parse argument for `inc` of type Int: true
 Usage: add [--num] <Int> [--inc] <Int>
-Error: invalid argument for num: 2.1
+Error: could not parse argument for `num` of type Int: 2.1
 Usage: add [--num] <Int> [--inc] <Int>
-Error: invalid argument for inc: 3.1415921535
+Error: could not parse argument for `inc` of type Int: 3.1415921535
 Usage: add [--num] <Int> [--inc] <Int>
-Error: invalid argument for num: 192.168.1.1
+Error: could not parse argument for `num` of type Int: 192.168.1.1
 Usage: add [--num] <Int> [--inc] <Int>
-Error: invalid argument for num: false
-Error: invalid argument for inc: true
+Error: could not parse argument for `num` of type Int: false
+Error: could not parse argument for `inc` of type Int: true
 Usage: add [--num] <Int> [--inc] <Int>
-Error: invalid argument for num: Hello
-Error: invalid argument for inc: world!
+Error: could not parse argument for `num` of type Int: Hello
+Error: could not parse argument for `inc` of type Int: world!
 Usage: add [--num] <Int> [--inc] <Int>