[ ghc-Bugs-1344553 ] GHC and GHCi hang when compiling simple program

Bugs item #1344553, was opened at 2005-11-01 05:40
Message generated for change (Comment added) made by simonpj
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Category: Compiler
Group: None
>Status: Closed
>Resolution: Wont Fix
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: GHC and GHCi hang when compiling simple program

Initial Comment:
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@xxxxxxxxxxxxxx

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>Comment By: Simon Peyton Jones (simonpj)
Date: 2005-11-01 10:12

Message:
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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You can respond by visiting: 
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