Constructor properties are not properly copied

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The matchesName method in scala.tools.nsc.transform.Constructors.scala currently matches any parameter which starts with the param.name, followed by the join symbol ($). This has the possibility of wrongly matching a parameter during compilation which will silently compile without warnings and introduce problems in runtime.

A minimal reproducible is easy, and will create the same problem in all use-case versions of Scala:

scala> case class Invoice(`total tax`: Int, total: Int)
defined class Invoice

scala> Invoice(`total tax` = 20, total = 120)
res0: Invoice = Invoice(20,20)

scala> res0.total
res1: Int = 20

A proposal would be to change the method from

def matchesName(param: Symbol) = param.name == name ||
  param.name.startsWith(name + nme.NAME_JOIN_STRING)

to

def matchesName(param: Symbol) = param.name == name ||
  param.name == name.append(nme.NAME_JOIN_STRING)

I'll make a PR with the failing test, to discuss the potential solution.

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Imported From: https://issues.scala-lang.org/browse/SI-9267?orig=1
Reporter: @melezov
Affected Versions: 2.9.3, 2.10.5, 2.11.6
See #8831
Attachments:

• ParamMatchTest.scala (created on Apr 10, 2015 2:55:30 AM UTC, 596 bytes)

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@retronym said:
Hi Marko,

I'm merging this with #8831. Could you please reference that ticket in your patch, and read through the comments over there?

Here was my prototype at a fix: scala/scala@2.11.x...retronym:ticket/8831

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@melezov said:
Ah, seems I only searched for constructor issues, my bad.
Also, my analysis seems to be a bit off as I didn't account for digits following $, so I closed the PR.