multiline literals doesn't work with CPP extension.

If LANGUAGE CPP is enabled then multiline literals stops working. Steps to reproduce.

1. write a program with multiline literal: cat 1.hs

test = "mutli\
   \line"

main = putStrLn test

1. it should compile without CPP:

ghc 1.hs [1 of 1] Compiling Main ( 1.hs, 1.o ) Linking 1 ...

1. compile it with CPP extension

Expected result: program compiles

ghc 1.hs
[1 of 1] Compiling Main             ( 1.hs, 1.o )
Linking 1 ...

Actual result: compilation breaks

ghc -XCPP 1.hs
[1 of 1] Compiling Main             ( 1.hs, 1.o ) [flags changed]

1.hs:1:18:
    lexical error in string/character literal at character 'l'

At least ghc-7.8.4 and ghc-7.10 are affected.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 5

added Tbug Trac import labels

closed

If you use -XCPP then you are responsible for ensuring that the output of the C preprocessor is a valid Haskell program. Line continuations (\ at the end of a line) are handled by the C preprocessor (so that you can define multi-line macros). See https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/options-phases.html#cpp-string-gaps.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedInvalid

See also Proposal/NativeCpp which may address this issue to some extent

added cpp label

Updated URL for the relevant bit of the GHC manual:

https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/phases.html?#cpp-and-string-gaps

mentioned in issue #16520 (closed)

marked #16520 (closed) as a duplicate of this issue

@hvr does Proposal/NativeCpp exist?

@cblp, I imagine that the original hyperlink was lost during the GitLab migration, but the new home for that wiki page is https://gitlab.haskell.org/ghc/ghc/wikis/proposal/native-cpp.

@RyanGlScott thanks

added Pnormal label