Expression `toString" suffix"` should trigger a warning

[noresttherein]

Scala version: 2.13.16

#Reproduction

	class IntBox(val x :Int) {
		def plus(other :IntBox) :String = toString" + " + other.x
		override def toString = x.toString
	}
	println(new IntBox(2).plus(new IntBox(2)))

#Problem

StringContext(ArraySeq( + ))2

This is almost certainly not what the programmer wanted. I propose it triggers a compiler warning about a missing +.

[noresttherein]

I must say I am kind of amused, especially when a project-wide search revealed a number of these.

[som-snytt]

Similarly for the eq interpolator, et al.

Welcome to Scala 3.8.4-RC3 (25.0.2, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.

scala> extension (sc: StringContext) def eq(things: String*) = "oops"
1 warning found
-- [E194] Potential Issue Warning: ---------------------------------------------
1 |extension (sc: StringContext) def eq(things: String*) = "oops"
  |                                  ^
  |Extension method eq will never be selected from type StringContext
  |because StringContext already has a member with the same name and compatible parameter types.
  |
  | longer explanation available when compiling with `-explain`
def eq(sc: StringContext)(things: String*): String

scala> { val x = "X"; eq" $x" }
val x: String = "X"
val res0: Boolean = false

scala> { val x = "X"; eq" $x $x" }
val x: String = "X"
val res1: Boolean = false

scala> extension (sc: StringContext) def toString(things: String*) = "oops"
def toString(sc: StringContext)(things: String*): String

scala> { val x = "X"; toString" $x $x" }
val x: String = "X"
val res2: String = "oops"

[som-snytt]

I created a ticket on Scala 3 (rather than transferring this one), where they may lint it or outlaw it.

I find that your idiosyncratic use of colon prepares my eye to accept your use of the toString interpolator!

Thanks, this was indeed very amusing.