[Mingw-notify] [ mingw-Bugs-497495 ] code doesnt compile

[<no...@so...>]

Bugs item #497495, was opened at 2001-12-28 18:18
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=102435&aid=497495&group_id=2435

Category: gcc
Group: None
>Status: Closed
>Resolution: Invalid
Priority: 5
Submitted By: vedad kajtaz (vedad)
Assigned to: Danny Smith (dannysmith)
Summary: code doesnt compile

Initial Comment:
Hello,

i've got a problem porting a piece of code from linux 
(gcc version egcs-2.90.27 980315 (egcs-1.0.2 release), 
yes it is _very_ old) to mingw. The code simply doesnt 
compile.

The problem is about using a class method as a 
callback.
In my project, i'm using a 'void *' as first argument 
to all callbacks thus being able to 'plug' both c and 
c++ (by passing class' "this" pointer as first 
argument) code to my application.


This is a sample of code which will raise compiling 
error:

--->8--->8--->8--->8--->8--->8--->8
#include <stdio.h>

typedef	void	(*cback)(void *, unsigned int x);

class	Test
{
private:
	unsigned int	me;

public:

	Test(unsigned int me)
	{
		this->me = me;
	}	
	void	Callback(int x)
	{
		printf("Test::Callback(%d), me=%d\n", 
x, me);
	}
};

void	TestCallback(cback function, void *ptr, 
unsigned int x)
{
	function(ptr, x);
}

int main(int argc, char *argv[])
{
	Test	*t1, *t2;

	t1 = new Test(10);
	t2 = new Test(20);

	TestCallback(Test::Callback, t1, 50);
	TestCallback(Test::Callback, t2, 100);
	
	return 0;
}

--->8--->8--->8--->8--->8--->8--->8

This compiles nicely on linux (except the 
warning "converting from `void (Test::*)(int)' to 
`void (*)(void *, unsigned int)") and prints, as 
expected:

Test::Callback(50), me=10
Test::Callback(100), me=20

With g++/mingw, i got a couple of lines that seem to 
be warnings, but g++ exits with error.


thanks
-- vedad kajtaz


----------------------------------------------------------------------

>Comment By: Danny Smith (dannysmith)
Date: 2002-01-03 01:32

Message:
Logged In: YES 
user_id=11494

It shouldn't compile.  The types do not match.

void Test::Callback(int) does not not match
type void (*)(void*, unsigned int)'

and that should throw an error in C++.  

If there is a bug in mingw version of gcc-2.95  it is in 
the reporting of the error. In 3.1 this diagnostic is 
provided:

bug.cpp: In function `int main(int, char**)':
bug.cpp:36: no matches converting function `Callback' to 
type `void (*)(void*,
   unsigned int)'
bug.cpp:17: candidates are: void Test::Callback(int)
bug.cpp:37: no matches converting function `Callback' to 
type `void (*)(void*,
   unsigned int)'
bug.cpp:17: candidates are: void Test::Callback(int)

Danny 

----------------------------------------------------------------------

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