Sigbjorn, Stef
Stef has tripped over a genuine bug in GHC 5.04. It's already fixed in
the head, but we hadn't back-patched it into 5.04. Since it has come up
again, its convinced us to back-patch, and the fix will be in the next
release of GHC, both on the 5.04 branch and in the HEAD.
The bug relates to a class method that constrains the class type
variable:
class Foo a where
op :: Eq a => ....
Notice the "Eq a" constrains the class variable 'a'. This is not
actually legal in Haskell 98. GHC claims to accept it, but actually
there's a nasty bug.
Simon
| -----Original Message-----
| From: Sigbjorn Finne [mailto:[EMAIL PROTECTED]]
| Sent: 14 February 2003 15:25
| To: Simon Peyton-Jones
| Subject: Fw: ghc crashes
|
| I haven't had the time to look at this one..perhaps it will crash
| similarly on non-win32 boxes too?
|
| --sigbjorn
|
| ----- Original Message -----
| From: <[EMAIL PROTECTED]>
| To: <[EMAIL PROTECTED]>
| Sent: Wednesday, February 05, 2003 05:36
| Subject: ghc crashes
|
|
| > Sigbjorn,
| >
| > Since I know how keen you people are to keep ghc as bugfree as
possible, I
| > thought you might find it interesting to learn that I ran into a
crash. I
| > am running ghc 5.04 on a windows 2000 professional computer. I have
made a
| > successful effort to render the error reproducible, so now you can
have a
| > go. I have attached all the files you need to reproduce the error.
Please
| > put them in a directory, and this is what happens:
| >
| > c:\> ghc -package text -fglasgow-exts -fallow-undecidable-instances
--make
| > SemTry -o SemTry.exe
| > ghc: chasing modules from: SemTry
| > Compiling UU_BinaryTrees ( UU_BinaryTrees.hs, UU_BinaryTrees.o )
| > Compiling UU_Pretty ( UU_Pretty.hs, UU_Pretty.o )
| > Compiling UU_Parsing ( UU_Parsing.hs, UU_Parsing.o )
| > Compiling UU_Scanner ( UU_Scanner.hs, UU_Scanner.o )
| > Compiling Auxiliaries ( Auxiliaries.lhs, Auxiliaries.o )
| > Compiling Classification ( Classification.lhs, Classification.o )
| > Compiling Typology ( Typology.lhs, Typology.o )
| > Compiling CC_aux ( CC_aux.lhs, CC_aux.o )
| >
| > CC_aux.lhs:141:
| > Warning: No explicit method nor default method for `flp'
| > In the instance declaration for `Morphic Morph'
| > Compiling AGtry ( AGtry.hs, AGtry.o )
| > Compiling CC ( CC.hs, CC.o )
| > Compiling Main ( SemTry.hs, ./SemTry.o )
| > ghc: linking ...
| >
| > <COMMENT: So far so good. The program has compiled well, and the
result
| > works: >
| >
| > c:\> SemTry arch
| > Element
| > OObject
| > Actor
| > Service
| > Object
| > MessageInst
| > Data_Object
| > Set
| > Class
| > Store
| > Parameter
| > Message
| > Event
| > UpdateEvent
| > StoreEvent
| > DeleteEvent
| > Location
| > Store
| > Time
| > Application
| >
| > <COMMENT: Now watch when I do a partial compilation. At this point I
have
| > saved the file CC.hs again, forcing recompilation>
| >
| > c:\> ghc -package text -fglasgow-exts -fallow-undecidable-instances
--make
| > SemTry -o SemTry.exe
| > ghc: chasing modules from: SemTry
| > Skipping UU_BinaryTrees ( UU_BinaryTrees.hs, UU_BinaryTrees.o )
| > Skipping UU_Pretty ( UU_Pretty.hs, UU_Pretty.o )
| > Skipping UU_Parsing ( UU_Parsing.hs, UU_Parsing.o )
| > Skipping UU_Scanner ( UU_Scanner.hs, UU_Scanner.o )
| > Skipping Auxiliaries ( Auxiliaries.lhs, Auxiliaries.o )
| > Skipping Classification ( Classification.lhs, Classification.o )
| > Skipping Typology ( Typology.lhs, Typology.o )
| > Skipping CC_aux ( CC_aux.lhs, CC_aux.o )
| > Skipping AGtry ( AGtry.hs, AGtry.o )
| > Compiling CC ( CC.hs, CC.o )
| > Skipping Main ( SemTry.hs, ./SemTry.o )
| > ghc: linking ...
| >
| > <COMMENT: everything seems fine, but the result (which should be
| identical)
| > no longer works!
| >
| > c:\> SemTry arch
| >
| > This is where the story ends. I get a windows error (in Dutch),
telling me
| > that SemTry has generated an application error. It explains that the
| > instruction on 0xc704768b refers to memory on 0xc704768b and that a
| > read-operation on memory has failed. (Click OK to end the program or
| CANCEL
| > to debug)
| >
| > A curious mistake, which forces me to recompile everything all the
time. I
| > thought you might like to know. Notice that "main" did not
recompile,
| > whereas I would expect it to. On other occasions, I noticed that
| everything
| > from "Typology" and up recompiled for no apparent reason. I don't
know if
| > this has something to do with it.
| >
| > Best regards, and please say hello from me to Simon PJ.
| > Stef Joosten
| > (See attached file: ghcbugsources.zip)
| >
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