#532 GHC and GHCi hang when compiling simple program

closed-wont-fix
nobody
Compiler (190)
5
2005-11-01
2005-11-01
Anonymous
No

When interpreting the following four-line program using
GHCi on Windows, GHCi hangs, never completing
compilation and giving no output:

data Paradox = Roll (Paradox -> Int)
unroll (Roll x) = x
selfapply x = unroll x x
uhoh = selfapply (Roll selfapply)

If I add a simple main method of the form 'main = do
print (fst ("Hello world", uhoh))', and then compile
with GHC, it hangs as well. However, if I use a main
method which does not mention uhoh, such as 'main = do
print "Hello world"', and then compile with GHC,
compilation is successful. However, in this case,
compilation with GHCi still hangs.

As it happens, I have seen this bug in both versions
6.4 and 6.4.1 of GHC for Windows.

-Sridhar Ramesh, sramesh@andrew.cmu.edu

Discussion

  • Simon Peyton Jones

    • status: open --> closed-wont-fix
     
  • Simon Peyton Jones

    Logged In: YES
    user_id=50165

    This is a documented bug.
    http://www.haskell.org/ghc/docs/latest/html/users_guide/bugs.
    html#bugs-ghc

    Until it bites on a program someone really cares about, I'm
    not going to fix it! (The only way I know to fix it involves
    imposing some arbitrary bound on the number of inlinings,
    which will be bad for some legitimate programs; or something
    more elaborate, which has a complexity burden of its own.)

    Simon

     

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