D Idioms

[Patrick Schluter]

On Friday, 2 October 2020 at 15:22:37 UTC, H. S. Teoh wrote:
> On Fri, Oct 02, 2020 at 03:12:01PM +0000, Guillaume Piolat via 
> Digitalmars-d wrote: [...]
>> For example, did you know that shifting an integer by more 
>> than 31 is Undefined Behaviour?
>
> This is not surprising; even in C/C++ it's well-known to be UB.
>
Yes, and the reason is due to the shift instruction in the CPU's. 
Some CPU's do the right thing like PowerPC and some do the wrong 
thing like x86. On x86 SHL instruction masks the shift number 
that is used, so

     uint x=1;
     x << 32

is equivalent to

     x << (32 & 0x1F)    // 0x3F in 64 bits mode

which is the same as

     x

and not 0 as

If the behaviour was fixed, the compiler would have to add a test 
in some implementations.