[Caml-list] Different behaviour in native and bytecode compilations (Compiler Bug?)

[Caml-list] Different behaviour in native and bytecode compilations (Compiler Bug?)

[nickgrey]

Hi Camlers. 

I have a program which uses the ncurses library.  It runs as expected when 
compiled natively, and when bytecode compiled in custom runtime mode.  But 
when compiled with ncurses bindings as a shared library, it produces 
different, seemingly incorrect output. 

I've created a minimal example of this behaviour.  The code is too still too 
big to attach, as it obviously includes bindings for ncurses. but I've 
archived it here (60KiB): 

http://draco.dyndns.org/~nick/bug.tar.gz 

Running make will build 3 executables. 

bug_native and bug_bytecode1 produce the output I expect (2 vertical rows of 
Xs), something like this: 

    X
    X
    X

    X
    X
    X 

but with bug_bytecode2, which is exactly the same code, but linked 
differently, the second row of Xs are horizontal, rather than vertical: 

    X
    X
    X



  XXX 

Any suggestions as to why this might happen?  I'm not an expert in O'Caml 
and especially not in using C bindings, so I could be doing something wrong, 
but the fact that it only happens with certain linking options makes me 
suspect it is a compiler bug.  Or could it be something wrong with the C 
bindings for ncurses?  (I didn't write them myself.) 

I've checked in the ocamlopt documentation, and I'm not using any of the 
constructs which behave differently under native compilation, but I don't 
think that's relevant anyway. 

I'm using O'Caml 3.07+2 and ncurses 5.4. 

Thanks in advance,
Nick 

PS. Thanks to all those who replied to my previous query on polymorphic 
variants.

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[Caml-list] Re: Different behaviour in native and bytecode compilations (Compiler Bug?)

[nickgrey]

John Gerard Malecki writes: 

> I built your program "out of the box" and I get the exact behavior for
> all executables. 
>
>      X
>      X
>      X 
>
>      X
>      X
>      X 
>
> :; ocamlc.opt -version
> 3.07
> :; ocamlopt.opt -version
> 3.07 
> 

Thanks John... your message prompted me to try another version.  I couldn't 
find a plain 3.07 (as it's been replaced by 3.07+2 on the website), but I 
downloaded and installed 3.06.  My demo program compiled with 3.06 this also 
displays the correct output.  (Correct as in the bug doesn't happen.)  So it 
seems that 3.06 and 3.07 work correctly, but 3.07+2 doesn't, for me at 
least. 

Perhaps someone on the list with 3.07+2 installed can compile my demo 
program and let me know what happens.  This will tell me if this is a bug 
introduced in 3.07+2 (or 3.07+1) or if it's a bug that just affects me.  
(Maybe I broke my O'Caml install somehow, although I don't really see how.) 

Regards,
Nick 

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