From:	"A. Sinan Unur" <asu1 AT cornell DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: posible bug in GCC syntax checker?
Date:	11 Oct 2001 22:09:37 GMT
Organization:	Cornell University
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"Tim Nicholson" <T DOT J DOT Nicholson AT btinternet DOT com> wrote in
news:9q4nm9$lc9$1 AT plutonium DOT btinternet DOT com: 

> Warning: Passing arg 1 of draw_item from incompatible pointer type
> 
> ------------- source code ---------
> //Local function prototype
> void draw_item(const int point_array[ ][2]);
> 
> //function main
> int main(void)
> {
> int item[5][2];
> 
>    {some code to initialise item};
>    draw_item(item);
> 
>    return;
> }
> 
> //function draw_item
> void draw_item(const int point_array[ ][2])
> {
>     {some code to draw a point_array};
> }
> 
> ----------- end of code --------
> 
> This seemed very strange so I tried changing the prototype to see if I
> could understand what was happening. Eventually, I discovered that I no
> longer got the warning when I defined the prototype as:
> 
> void draw_item(int (* const point_array) [2]);
> 
> Now, correct me if I am wrong, but is this not the same thing in
> practical terms?
> 
> I do not understand why the compiler complains about the first
> definition. Is it a GCC bug? I am using DJGPP GCC-2.95.2 : GNU C
> compiler binaries with no compiler flags.

It probably isn't a bug with GCC although I am no expert in rules regarding 
the decay of multi-dimensional arrays to pointers. Your code compiles 
without warnings if const is removed.

Note that the code also compiles without warnings if compiled as C++.

The answer to your question is tied to these facts but I do not know what 
the answer is. You may want to check with the folks on 
comp.lang.c.moderated.

sinan.
-- 
--------------------------------
A. Sinan Unur
http://www.unur.com/

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