#6144: Preprocessor line control suppressed by comments
------------------------------+---------------------------------------------
Reporter: holzensp | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler (Parser)
Version: 7.4.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Other | Testcase:
Blockedby: | Blocking:
Related: |
------------------------------+---------------------------------------------
Using the preprocessor and "purely functional" parser from the GHC API,
SrcSpan annotations in the AST turned out wrong. I have created a minimal
example to reproduce. It comprises three files, PPBugDemo.hs, ppbug.hs and
ppbug.h. PPBugDemo is the program calling the GHC API. It prints the
contents of ppbug.hs and ppbug.h, to show clearly what goes wrong.
Here is PPBugDemo:
{{{
module PPBugDemo where
import GHC
import GHC.Paths
import DriverPipeline
import DriverPhases
import HscMain
import DynFlags
import ErrUtils
import Outputable
import System.Directory
main :: IO ()
main = do
{- Initialising Ghc and getting dynflags + environment -}
(df,env) <- defaultErrorHandler defaultLogAction $ runGhc (Just
libdir) $ do
fs' <- getSessionDynFlags
let fs = fs' { includePaths = includePaths fs' ++ ["."] }
setSessionDynFlags fs
s <- getSession
return (fs,s)
{- Running the preprocessor and cleaning up after it;
- it *must* (don't know why) go via a temp-file -}
(df,fn') <- preprocess env ("ppbug.hs", Just $ Cpp HsSrcFile)
cnt <- readFile fn'
removeFile fn'
{- Warnings aren't relevant to this example, so ignore them -}
let res = either (printBagOfErrors df >> fail "FAILED") snd
(parser cnt df "ppbug.hs")
{- Reporting results -}
let showCnt = unlines . zipWith (\n l -> show n ++ '\t':l) [1..] .
lines
org <- readFile "ppbug.hs"
hdr <- readFile "ppbug.h"
putStrLn $ "Original file:\n" ++ showCnt org
putStrLn $ "Header file:\n" ++ showCnt hdr
putStrLn $ "Preprocessed file:\n" ++ showCnt cnt
putStrLn . showSDocDebug . ppr $ res
}}}
and here is the resulting output:
{{{
Original file:
1 {-# LANGUAGE CPP #-}
2 {-
3 #include "ppbug.h"
4 -}
5 type Foo = Int
6
Header file:
1 bar [] = []
2 bar (x:xs) = bar xs
Preprocessed file:
1 # 1 "ppbug.hs"
2 # 1 "<built-in>"
3 # 1 "<command-line>"
4 # 1 "ppbug.hs"
5 {-# LANGUAGE CPP #-}
6 {-
7
8 # 1 "ppbug.h" 1
9 bar [] = []
10 bar (x:xs) = bar xs
11 # 4 "ppbug.hs" 2
12 -}
13 type Foo = Int
14
{ppbug.hs:1:1}
{ppbug.hs:9:1-14}
type {ppbug.hs:9:6-8}
Foo{tc} =
{ppbug.hs:9:12-14}
Int{tc}
}}}
The parser has annotated the AST with location information for Foo. It
says it's on line 9 of ppbug.hs, whilst it actually came from line 5. Line
11 from the output of the preprocessor sets the line number back to 4
(starting from line 12), but it seems this line control is ignored for
residing in {- -} comments.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6144>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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