RPPL crashes on fresh names

[nicolasstucki]

minimized code

scala> def g[C[_

This issue was introduced in #7620. The problem is that there is no compilation unit set when parsing in the highlighter of the REPL.

Stack trace

cala> def g[C[Exception in thread "main" java.lang.NullPointerException
        at dotty.tools.dotc.core.NameKinds$UniqueNameKind.fresh(NameKinds.scala:218)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParam$1(Parsers.scala:2744)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClause$$anonfun$2$$anonfun$1(Parsers.scala:2752)
        at dotty.tools.dotc.parsing.Parsers$Parser.tokenSeparated(Parsers.scala:586)
        at dotty.tools.dotc.parsing.Parsers$Parser.commaSeparated(Parsers.scala:594)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClause$$anonfun$1(Parsers.scala:2752)
        at dotty.tools.dotc.parsing.Parsers$Parser.enclosed(Parsers.scala:554)
        at dotty.tools.dotc.parsing.Parsers$Parser.inBrackets(Parsers.scala:563)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClause(Parsers.scala:2753)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClauseOpt(Parsers.scala:2756)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParam$1(Parsers.scala:2747)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClause$$anonfun$2$$anonfun$1(Parsers.scala:2752)
        at dotty.tools.dotc.parsing.Parsers$Parser.tokenSeparated(Parsers.scala:586)
        at dotty.tools.dotc.parsing.Parsers$Parser.commaSeparated(Parsers.scala:594)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClause$$anonfun$1(Parsers.scala:2752)
        at dotty.tools.dotc.parsing.Parsers$Parser.enclosed(Parsers.scala:554)
        at dotty.tools.dotc.parsing.Parsers$Parser.inBrackets(Parsers.scala:563)
        at dotty.tools.dotc.parsing.Parsers$Parser.typeParamClause(Parsers.scala:2753)
        at dotty.tools.dotc.parsing.Parsers$Parser.defDefOrDcl(Parsers.scala:3137)
        at dotty.tools.dotc.parsing.Parsers$Parser.defOrDcl(Parsers.scala:3024)
        at dotty.tools.dotc.parsing.Parsers$Parser.localDef(Parsers.scala:3704)
        at dotty.tools.dotc.parsing.Parsers$Parser.blockStatSeq$$anonfun$1(Parsers.scala:3726)
        at dotty.tools.dotc.parsing.Parsers$Parser.checkNoEscapingPlaceholders(Parsers.scala:495)
        at dotty.tools.dotc.parsing.Parsers$Parser.blockStatSeq(Parsers.scala:3734)
        at dotty.tools.dotc.printing.SyntaxHighlighting$.highlight(SyntaxHighlighting.scala:122)
        at dotty.tools.repl.JLineTerminal$Highlighter.highlight(JLineTerminal.scala:76)
        at org.jline.reader.impl.LineReaderImpl.getHighlightedBuffer(LineReaderImpl.java:3633)
        at org.jline.reader.impl.LineReaderImpl.getDisplayedBufferWithPrompts(LineReaderImpl.java:3615)
        at org.jline.reader.impl.LineReaderImpl.redisplay(LineReaderImpl.java:3554)
        at org.jline.reader.impl.LineReaderImpl.doCleanup(LineReaderImpl.java:2340)
        at org.jline.reader.impl.LineReaderImpl.cleanup(LineReaderImpl.java:2332)
        at org.jline.reader.impl.LineReaderImpl.readLine(LineReaderImpl.java:626)
        at org.jline.reader.impl.LineReaderImpl.readLine(LineReaderImpl.java:404)
        at dotty.tools.repl.JLineTerminal.readLine(JLineTerminal.scala:68)
        at dotty.tools.repl.ReplDriver.readLine$1(ReplDriver.scala:115)
        at dotty.tools.repl.ReplDriver.loop$1(ReplDriver.scala:125)
        at dotty.tools.repl.ReplDriver.runUntilQuit$$anonfun$1(ReplDriver.scala:130)
        at dotty.tools.repl.ReplDriver.withRedirectedOutput(ReplDriver.scala:148)
        at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:130)
        at dotty.tools.repl.Main$.main(Main.scala:6)
        at dotty.tools.repl.Main.main(Main.scala)

[smarter]

Thanks for the repro, I pushed a fix as part of #7691