Re: recasting an error to a warning?

[Matthew Woehlke <mw_triad at users dot sourceforge dot net>]

Mark Winstead wrote:
> Using gcc on a Itanium chip with Linux SUSE I get the error message (and 
> similar ones):
> /localviews/hpc/vc/src/ace/ace_virtual.cpp:1714: error: cast from 
> 'void*' to 'int' loses precision
>
> I know that what is happening is a 64 bit value is being cast to a 32 
> bit value. The problem is I've counted 427 instances of this or a like 
> error. The developer's say they've made this code work on other 64 bit 
> platforms -- what is going on is that they took a 32 bit value and 
> stored it in the larger, and this is coming back down. (no, I don't know 
> why they did this). So it just needs a simple truncation.
>
> Either there is a flag hidden in the makefiles that is promoting a 
> warning to an error here, or I hope there is a flag that casts this 
> error to a warning. Help?

I don't have this problem in any C++ code I maintain, but the way we 
suppress the warning in C code is by Writing Good Code; IOW, make it 
explicit what you are doing, like this:

int foo = (int)(long)ptr;

The cast from void* to long is usually correct (if not, replace it with 
something that you erliably typedef to be 'an integer whose size == 
sizeof(void*)'). Then you can safely downcast the larger integer to a 
(potentially) smaller integer (int).

--
Matthew
Microsoft: driving people fscking insane...