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Add error message IdentifierExpected #1633

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Merged
merged 1 commit into from
Oct 31, 2016
Merged

Add error message IdentifierExpected #1633

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3 changes: 2 additions & 1 deletion src/dotty/tools/dotc/parsing/JavaParsers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ import Symbols._
import ast.Trees._
import Decorators._
import StdNames._
import dotty.tools.dotc.reporting.diagnostic.messages.IdentifierExpected
import dotty.tools.dotc.util.SourceFile
import util.Positions._
import annotation.switch
Expand Down Expand Up @@ -230,7 +231,7 @@ object JavaParsers {
case AppliedTypeTree(_, _) | Select(_, _) =>
tree
case _ =>
syntaxError("identifier expected", tree.pos)
syntaxError(IdentifierExpected(tree.show), tree.pos)
errorTypeTree
}
}
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2 changes: 1 addition & 1 deletion src/dotty/tools/dotc/parsing/Parsers.scala
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Expand Up @@ -316,7 +316,7 @@ object Parsers {
case id @ Select(qual, name) =>
cpy.Select(id)(qual, name.toTypeName)
case _ =>
syntaxError("identifier expected", tree.pos)
syntaxError(IdentifierExpected(tree.show), tree.pos)
tree
}

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24 changes: 24 additions & 0 deletions src/dotty/tools/dotc/reporting/diagnostic/messages.scala
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Expand Up @@ -691,4 +691,28 @@ object messages {
|${s"trait A[${mods.flags} type $identifier]"}
|""".stripMargin
}

case class IdentifierExpected(identifier: String)(implicit ctx: Context) extends Message(25) {
val kind = "Syntax"

val msg = "identifier expected"

val wrongIdentifier = s"def foo: $identifier = {...}"

val validIdentifier = s"def foo = {...}"

val explanation = {
hl"""|A valid identifier expected, but `$identifier` found.
|Let the compiler infer the type for you.
|For example, instead of:
|
|$wrongIdentifier
|
|Write your code like:
|
|$validIdentifier
|
|""".stripMargin
}
}
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So I have a couple of comments/questions on this explanation:

  • Does it make sense for all cases?
  • Could you show the user their code and the correct way to rewrite it? E.g: def foo: int = { ... } => def foo = { ... }
  • There are some weird things when it comes to the language like "Because of Scala's stronger type" - wat? Have a look through it and I'm sure you'll find places to correct :)
  • The line breaking is increasing, first line is something like 60 chars, the second 65 and third 90+, try to even it out.
  • The line with "Here we explicitly" is too long (84 chars). We want a line to be max 80 chars (the standard terminal width).

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@iamthiago iamthiago Oct 28, 2016 •
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Hi @felixmulder thanks for your comments. I'm going through your cases and explain to you what I thought right?

1 - Actually, to be honest, the only piece of code I could reproduce this error was this:

def foo: this = "bar"

and it goes to the Parsers class.

Is there any other case I could reproduce it, so I can make sure nothing was left behind?

2 - Get the user code, you mean I could use the Tree to show the user wrong code and give the correct one? In fact I could pass the Tree inside the class and use it. Don't know how to play with Trees but I will figure out.

3 - yeah, that one was difficult to write. I mean, Scala has a strong type system, which is good, everything has a type where it could be inferred by the compiler or not(in case the user provided it).

4 & 5 - No problem :)

}