There was also some talk in the math/bits proposal thread
https://github.com/golang/go/issues/18616 about creating a
math/checked library but to my knowledge no one's opened a proposal
for that yet
On Fri, Mar 17, 2017 at 6:49 AM, Ian Lance Taylor <i...@golang.org> wrote:
> On Thu, Mar 16, 2017 at 11:04 PM, Konstantin Khomoutov
> <flatw...@users.sourceforge.net> wrote:
>> On Tue, 14 Mar 2017 07:12:01 -0700
>> Ian Lance Taylor <i...@golang.org> wrote:
>>
>>> > I was thinking about the type safety of uint in go, and comparing
>>> > it for a similar problem.
>>> >
>>> > If I have this go code:
>>> >
>>> > var x uint
>>> > x--
>>> >
>>> > The value of x is then the maximal value of uint, which is probably
>>> > not what the gother wanted (I think, is there any particular use
>>> > cases for that that you know of?)
>>> >
>>> > So my question is: why does go allow that, and for example panics
>>> > on index out of range of an array? Doesn't it make sense that it
>>> > also should panic in this case?
>>>
>>> Well, there are also uses for modulo arithmetic. If we make this
>>> panic, writing the equivalent operation that doesn't panic seems
>>> awkward. I think there is a better case to be made that signed types
>>> should panic on overflow, the main question there being the run time
>>> efficiency cost.
>>
>> I think I might have asked this already but wouldn't it be possible to
>> add (in the future) a two-argument form for integer arithmetic
>> operations and bit shifts, so that the second argument, if used, is set
>> to the overflow status?
>>
>> Like in:
>>
>> var x uint
>> if x, of := x-1; of {
>> panic("Integer underflow");
>> }
>>
>> var y uint32
>> if y, cf := x << 33; cf {
>> panic("Bit carrying detected");
>> }
>>
>> I'm not too much versed in CPU hardware, so offhand I can only say that
>> Z80 and x86 do support overflow and carrying detection.
>
> See https://golang.org/issue/6815.
>
> Ian
>
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