Add an error message class for the method's missing arguments #3394
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| @@ -1908,7 +1908,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit | |||
| def methodStr = err.refStr(methPart(tree).tpe) | |||
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| def missingArgs(mt: MethodType) = { | |||
| ctx.error(em"missing arguments for $methodStr", tree.pos) | |||
| ctx.error(MissingArgumentsForMethod(methodStr), tree.pos) | |||
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This one is tricky. The idea of error messages is to contains useful information not only for the compiler but also for tools such as IDE. A string is not very helpful for an IDE. Ideally we would want to include the symbol of the method as well as the missing arguments. It should be something like:
case class MissingArgumentsForMethod(method: Symbol, missings: List[Symbol])(implicit ctx: Context)You should look at what def methodStr is doing in order to get this information.
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I totally agree that providing useful information for IDEs is a must, but here's the thing, this error message is about using a so-called nullary method which is described in this document.
So, there are actually no missing arguments which a user forgot to provide because a method doesn't accept any arguments.
Maybe the initial error message is a little bit ambiguous. Because when I see this:
scala> def greet(): String = "hello"
def greet(): String
scala> greet
1 |greet
|^^^^^
|missing arguments for method greet
It makes me think that I forgot to provide the actual arguments for the method when the actual problem is that Dotty is stricter than Scala in terms of calling nullary methods.
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I agree the error message as well as the name of the message is ambiguous. If this message only applies for missing empty parameter list, then I would update the message accordingly
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Superseded by #3407 |
This PR is related to #1589. Specifically, it adds a new error message class for the following case
Typer.scala:1898 (def missingArgs)