Fix #2426: Use Scala-2 syntax for annotations of class constructors #2432
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…onstructors Use Scala-2 compatible syntax for annotations of primary class constructors. In fact, we can drop Scala 2's restriction that such annotations may only have one parameter list.
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This change caused a lot of complexity. More than 100 loc to deal with this issue. |
| else { | ||
| td.copyFrom(following.head) | ||
| following = following.tail | ||
| } |
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Looks like a missing closing brace here.
| val mods = modifiers(accessModifierTokens, annotsAsMods()) | ||
| if (mods.hasAnnotations && !mods.hasFlags) | ||
| if (in.token == THIS) in.nextToken() | ||
| else syntaxError(AnnotatedPrimaryConstructorRequiresModifierOrThis(owner), mods.annotations.last.pos) |
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This means we can drop this Message subclass (but we must be careful to leave a dummy id in its place in the ErrorMessageID enum to avoid changing the error number of every subsequent message).
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| /** Handle first argument of an argument list to an annotation of | ||
| * a primary class constructor. If the current token either cannot | ||
| * start an expression or is an identifier and is followed by `:`, |
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But a : can legitimately appear in an argument list, e.g:
class ann(x: Any) extends scala.annotation.Annotation
object Test {
val elem: Int = 1
class Foo @ann(elem: Float) (x: String)
}Banning multiple param lists in constructor annotations still seems better to me than having complex rules to guess whether something is or isn't an argument list :).
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I don't see how banning multi param solves that problem?
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Indeed, it seems that scalac always expects a primary constructor annotation to have exactly one parameter list (having zero parameter lists won't be parsed correctly), which is a more annoying restriction. I'm still not super enthusiastic about adding so much special-casing in the parser (this will need to be replicated in scala.meta for example, /cc @xeno-by), but I'm not opposed to it. The main annoyance is that if seemingly valid code is misinterpreted, you'll get a very confusing error message, but that could be left as a future improvement.
This error can no longer be raised.
To maintain compatibility with Scala2 we a `()` argument list as belonging to a primary constructor annotation if it is the first argument list for that annotation.
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I tweaked it now so that the first |
When doing the indentation-based syntax, I found a better hammer: We can simply copy the Scanner at the current offset to create a lookahead Scanner. With that, the logic for handling primary constructor arguments could be greatly simplified. Most of scala#2432 could be reverted.
When doing the indentation-based syntax, I found a better hammer: We can simply copy the Scanner at the current offset to create a lookahead Scanner. With that, the logic for handling primary constructor arguments could be greatly simplified. Most of scala#2432 could be reverted.
Use Scala-2 compatible syntax for annotations of primary class constructors.
In fact, we can drop Scala 2's restriction that such annotations may only
have one parameter list.