f interpolator doesn't process backslash escapes

[lrytz]

Scala 2:

scala> f"yes\\\no"
val res0: String =
yes\
o

Scala 3:

scala> f"yes\\\no"
val res0: String = yes\\\no

[odersky]

I don't think it's the parser. Interpolated strings do not process "\" escapes. That's for the interpolator to do. Or did I get that wrong?

[lrytz]

yes, the interpolator should handle the escapes. i haven't checked why it doesn't do so in dotty

[odersky]

Why is this a "transform" issue? Isn't the F-interpolator a macro?

[abgruszecki]

Assigning Nico, since his student worked on the interpolator.

[som-snytt]

By coincidence, my dotty repo is on the branch for #9939 where I've only collected examples of divergent behavior. Every 6 months or so, I intend to take a look.

[smarter]

It used to be a macro but it's been intrinsified in the compiler: https://github.com/lampepfl/dotty/blob/master/compiler/src/dotty/tools/dotc/transform/localopt/StringContextChecker.scala

[nicolasstucki]

We still want to port the Scala 2 implementation of the f interpolation checker. We should probably not fix this one and just port it, which should fix the issue.

[nicolasstucki]

Same solution as in #9939 (comment)