DIP 1010--Static foreach--Formal Review

[Steven Schveighoffer via Digitalmars-d]

On 7/11/17 7:21 PM, H. S. Teoh via Digitalmars-d wrote:
> On Tue, Jul 11, 2017 at 07:18:51PM -0400, Steven Schveighoffer via Digitalmars-d wrote:
> [...]
>> 3. The only controversial part I see is that `break` doesn't break
>> from the foreach loop. While I agree with the reasoning, and support
>> that concept, the truth is we currently have a "poor man's" static
>> foreach using a foreach over a tuple, and that DOES break from the
>> loop.
> 
> This is a false impression.  It actually does not break from the loop,
> but inserts a break in the generated code, and continues to unroll the
> rest of the loop.  It's only at codegen that the subsequent iterations
> are detected as dead code and elided. See:
> 
> 	https://wiki.dlang.org/User:Quickfur/Compile-time_vs._compile-time#.22static.22_foreach_does_NOT_interpret_break_and_continue

Yes, I know that it still generates all the code, but the break is still 
interpreted as breaking out of the loop. Timon's proposal says it "does 
not interact with break", so I interpret that as meaning it should break 
out of whatever construct is surrounding the loop, not the loop itself.

Currently this:

foreach(j; 0 .. 2)
foreach(i; AliasSeq!(0, 1))
{
     writeln(i);
     static if(i == 0)
       break;
}

will print
0
0

Whereas with my understanding, this:

foreach(j; 0 .. 2)
static foreach(i; 0 .. 2)
{
     writeln(i);
     static if(i == 0)
        break;
}

would print
0

This seems too confusing.

-Steve