[PATCH][4.3] Deprecate -ftrapv

[Robert Dewar]

David Daney wrote:
> Mark Mitchell wrote:
>> Richard Guenther wrote:
>>> This is a request to depcrecate -ftrapv which has numerous problems
>>> making it not work as expected since a long time.  As nobody seems
>>> to have the energy to ensure it is working I propose to deprecate it
>>> for GCC 4.3 to make it possible to remove it during 4.4 (and not
>>> block removing libcall notes by it).
>> Why doesn't it work?  Can it be made to work relatively easily?  Do we 
>> need functionality like this for Ada or Java?
>>
> 
> Java only traps on integer division by zero.  As I understand it, this 
> is handled by a different mechanism.

The situation is:

Ada: integer overflow checking required (it's off by default in GNAT,
but you get required standard behavior by using -gnato, the reason
it is off by default is that the code is so horrible).

Java: integer overflow checking is prohibited, wrap around semantics
is required (IMO a horrible choice, but there you are!)

C: integer overflow undefined, checking desirable at least for
debugging purposes.

I think latest Fortran is same as C, can someone confirm?
> 
> David Daney