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Re: [rfa] handle integer downsizing correctly in C++ overloading
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: David Carlton <carlton at math dot stanford dot edu>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Tue, 4 Feb 2003 13:32:22 -0500
- Subject: Re: [rfa] handle integer downsizing correctly in C++ overloading
- References: <ro1fzr9gkie.fsf@jackfruit.Stanford.EDU>
On Fri, Jan 31, 2003 at 11:57:29AM -0800, David Carlton wrote:
> GDB currently won't let you do narrowing integer conversions when
> calling an overloaded C++ function: compile this,
>
> int overloadChar(char c)
> {
> return 29;
> }
>
> int main()
> {
> overloadChar(1);
> }
>
> break on main, and try to print overloadChar(1).
>
> The problem is that gdbtypes.h defines both INTEGER_COERCION_BADNESS
> and INTEGER_CONVERSION_BADNESS. The former is unacceptably bad; the
> latter isn't preferred, but isn't acceptable. And in all (or almost
> all) cases, the type comparison functions use INTEGER_COERCION_BADNESS
> when doing narrowing integer comparisons, when they should use
> INTEGER_CONVERSION_BADNESS.
>
> In fact, INTEGER_COERCION_BADNESS shouldn't exist: there's no such
> thing as an unacceptably bad integer conversion. So this patch
> changes all uses of INTEGER_COERCION_BADNESS to refer to
> INTEGER_CONVERSION_BADNESS, deletes INTEGER_COERCION_BADNESS, and also
> deletes FLOAT_COERCION_BADNESS (which is similarly unnecessary but
> which is already correctly unused). And there's a testsuite patch
> included to catch this as well.
>
> Tested on i686-pc-linux-gnu/GCC3.1/DWARF-2; OK to commit?
I (still) don't have a copy of the standard; I think I'll see about
getting one this week. However, your explanation makes sense, and
matches my reading of the conversion code that GCC uses for overload
resolution (gcc/cp/call.c:build_conv and standard_conversion). This
patch is OK.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer