assert semantic change proposal

[Matthias Bentrup via Digitalmars-d]

On Wednesday, 6 August 2014 at 13:31:54 UTC, Ola Fosheim Grøstad 
wrote:
> On Wednesday, 6 August 2014 at 12:41:16 UTC, Artur Skawina via 
> Digitalmars-d wrote:
>> The compiler can /assume/ that the condition never fails. 
>> Hence, it does
>> not need to generate any code to check that the assumption is 
>> valid.
>
> Exactly, worse example using a coroutine:
>
> «
> label:
> …
> while(running) { // forevah!
>    … yield …
> }
> …
> assume(anything local not assigned below label) // reachable, 
> but never executed
> »
>
> is equivalent to:
>
> «
> assume(anything local not assigned below label) // optimize 
> based on this
> label:
> …
> while(running) {
>    … yield …
> }
> »
>
> Woops?

But even if there is no explicit assert()/assume() given by the 
developer, I guess the optimizer is free to insert assumes that 
are provably correct, e.g.

   while(running) {
     ...don't assign to running, don't break...
   }

is equivalent to

   while(running) {
     ...don't assign to running, don't break...
   }
   assume(!running);

is equivalent to

   assume(!running);
   while(running) {
     ...don't assign to running, don't break...
   }

is equivalent to

   assume(!running);


So I take the compiler is allowed to throw away code without any 
asserts already ?