[m-dev.] bugs?

Peter Schachte schachte at cs.mu.OZ.AU
Tue Feb 3 15:09:57 AEDT 2004

Firstly, there are several small typos in the reference manual section
on "Using C pointers".  I'm attaching a corrected version of that

Secondly, when I try to compile that code, I get several warnings from
the C compiler about missing int<->pointer casts:

    mudla% mmake pointer_example.o 14:57
    mmc --compile-to-c --grade asm_fast.gc pointer_example >
    pointer_example.err 2>&1
    mgnuc --grade asm_fast.gc -- -c pointer_example.c -o pointer_example.o
    pointer_example.m: In function `pointer_example_module0':
    pointer_example.m:27: warning: assignment makes integer from pointer
    without a cast
    pointer_example.m: In function `pointer_example_module1':
    pointer_example.m:31: warning: passing arg 2 of `perform_calculation'
    makes pointer from integer without a cast
    pointer_example.m:31: warning: assignment makes integer from pointer
    without a cast
    rm pointer_example.c

Any idea what the problem could be, or how to fix it?  I'm using gcc
3.3.2 (Debian).  I get similar messages for any foreign interface code
I compile.

Thanks for any help you can give.

Peter Schachte              The trouble with the rat race is that even if you
schachte at cs.mu.OZ.AU        win, you're still a rat.
www.cs.mu.oz.au/~schachte/      -- Lily Tomlin 
Phone: +61 3 8344 1338      
-------------- next part --------------
:- module pointer_example.

:- interface.

:- type complicated_c_structure.

% Initialise the abstract C structure that we pass around in Mercury.
:- pred initialise_complicated_structure(complicated_c_structure::uo) is det.

% Perform a calculation on the C structure.
:- pred do_calculation(int::in, complicated_c_structure::di, 
        complicated_c_structure::uo) is det.

:- implementation.

% Our C structure is implemented as a c_pointer.
:- type complicated_c_structure --->

:- pragma c_header_code("
        extern struct foo *init_struct(void);
        extern struct foo *perform_calculation(int, struct foo *);

:- pragma c_code(initialise_complicated_structure(Structure::uo),
        "Structure = init_struct();").

:- pragma c_code(do_calculation(Value::in, Structure0::di, Structure::uo),
        "Structure = perform_calculation(Value, Structure0);").

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