Range non-emptyness assertions and opIndex

[Rene Zwanenburg via Digitalmars-d-learn]

On Friday, 1 July 2016 at 10:35:04 UTC, Nordlöw wrote:
> I think this is a important issue since asserts are not 
> optimized away in release mode and D is very much about 
> performance.

Asserts are removed in release mode, enforce isn't. Here's an 
example:

=====
void main(string[] args)
{
	assert(args.length >= 1);
}
=====

dmd testfile.d

This calls the assert function as expected:
=====
_Dmain:
   0000000000000000: 55                 push        rbp
   0000000000000001: 48 8B EC           mov         rbp,rsp
   0000000000000004: 48 83 39 01        cmp         qword ptr 
[rcx],1
   0000000000000008: 73 0E              jae         
0000000000000018
   000000000000000A: B9 03 00 00 00     mov         ecx,3
   000000000000000F: 48 83 EC 20        sub         rsp,20h
   0000000000000013: E8 00 00 00 00     call        
_D5test28__assertFiZv
   0000000000000018: 31 C0              xor         eax,eax
   000000000000001A: 5D                 pop         rbp
   000000000000001B: C3                 ret
=====

Now compiling in release mode:
dmd -release testfile.d

No assert in sight:
=====
_Dmain:
   0000000000000000: 55                 push        rbp
   0000000000000001: 48 8B EC           mov         rbp,rsp
   0000000000000004: 31 C0              xor         eax,eax
   0000000000000006: 5D                 pop         rbp
   0000000000000007: C3                 ret
=====