External preprocessor not used after TH name quote

Module

{-# LANGUAGE CPP, TemplateHaskell #-}

module Main where

main = do
  putStrLn $ show 'id
  putStrLn __FILE__

fails to compile with external preprocessor:

> ghc -pgmP cpphs -optP --cpp Main.hs
[1 of 1] Compiling Main             ( Main.hs, Main.o )

Main.hs:7:12: Not in scope: `__FILE__'

__FILE__ is not expanded:

> ghc -E -pgmP cpphs -optP --cpp Main.hs
> cat Main.hspp
{-# LINE 1 "Main.hs" #-}
#line 1 "Main.hs"
{-# LANGUAGE CPP, TemplateHaskell #-}

module Main where

main = do
  putStrLn $ show 'id
  putStrLn __FILE__

Without external preprocessor (just ghc Main.hs) module compiles successfully.

Move name quote after __FILE__, like this:

{-# LANGUAGE CPP, TemplateHaskell #-}

module Main where

main = do
  putStrLn __FILE__
  putStrLn $ show 'id

and it work with external preprocessor just fine:

> ghc -pgmP cpphs -optP --cpp Main.hs
[1 of 1] Compiling Main             ( Main.hs, Main.o )
Linking Main ...
> ./Main
Main.hs
GHC.Base.id

Trac metadata

Trac field	Value
Version	7.4.1
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

I suspect that cpp treats the 'id as opening a quotation, and doesn't interpret the FILE inside that quote. So this isn't a bug in GHC, more just that cpp isn't doing what you want.

Reopen if you think it's a bug in GHC

Simon

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedInvalid

added Pnormal label