collectModuleName breaks in the presence of MagicHash

[isovector]

Consider the perfectly reasonable name under -XMagicHash: Jn#. This causes an error:

Unable to parse RdrNameStr: "Jn#"
CallStack (from HasCallStack):
  error, called at src/GHC/SourceGen/Name/Internal.hs:106:10 in ghc-source-gen-0.4.0.0-5bO8D09FGq6LIxEy1df7VD:GHC.SourceGen.Name.Internal

[judah]

Thanks for the report. This should be an straightforward fix for the IsString instance in GHC.SourceGen.Name.Internal. Would you like to send a patch?