dotty.tools.dotc.transform.localopt

Drop unused trailing map calls in for comprehensions.

We can drop the map call if:

• it won't change the type of the expression, and
• the function is an identity function or a const function to unit.

The latter condition is checked in Desugar.scala#makeFor

MiniPhase to transform s and raw string interpolators from using StringContext to string concatenation. Since string concatenation uses the Java String builder, we get a performance improvement in terms of these two interpolators.

More info here: https://medium.com/@dkomanov/scala-string-interpolation-performance-21dc85e83afd

Formatter string checker.