MultilineStrings for interpolation

compiler/GHC/Driver/MultilineStrings.hs

@@ -17,10 +17,16 @@ convertMultilineStrings s = go s WaitingForString 0
   InString -> case s of
    "" -> error "we are in a mutline string, but text ended unexpectedly"
    '\n':'"':'"':'"':s -> '"':'\n' : go s WaitingForString 0
+   '#':'{':s -> '#':'{' : go s InInterpolationSection charCnt
    '"':s -> '\\':'"' : go s state charCnt
    '\\':s -> '\\':'\\' : go s state charCnt
    '\n':s -> "\\n\"\n" ++ replicate charCnt ' ' ++ "++ \"" ++ go s state charCnt
    c:s -> c : go s state charCnt
+  InInterpolationSection -> case s of
+   '\n':_ -> error "we are in an interpolation section in mutline string, but text line ended unexpectedly"
+   '}':s -> '}' : go s InString charCnt
+   c:s -> c : go s state charCnt
+
   where
   skipOneLineComment "" = go "" state charCnt
   skipOneLineComment s@('\n':_) = go s state charCnt
@@ -33,3 +39,4 @@ convertMultilineStrings s = go s WaitingForString 0
 data State
  = WaitingForString
  | InString
+ | InInterpolationSection