Request for Comment assert(__ctfe)

[Steven Schveighoffer]

On 4/8/20 2:53 PM, Jacob Carlborg wrote:
> On 2020-04-07 22:43, Stefan Koch wrote:
>> On Tuesday, 7 April 2020 at 17:52:44 UTC, Jacob Carlborg wrote:
>>>
>>> void foo()
>>> {
>>>     assert(__ctfe);
>>> }
>>>
>>> void main() @system
>>> {
>>>     try
>>>         foo();
>>>     catch (AssertError)
>>>     {}
>>> }
>>
>> firstly Does anybody actually do this?
> 
> Ok, let me tweak the example a bit:
> 
> void foo()
> {
>      assert(__ctfe);
> }
> 
> unittest
> {
>      foo();
> }
> 
> druntime catches _all_ exceptions:
> 
> https://github.com/dlang/druntime/blob/46867186035fdf5ec2596efbb770627518ff0919/src/core/runtime.d#L617 
> 
> 
> Regardless if anyone does it or not, it's still a breaking change. Then 
> we can of course argue the impact of the breaking change, how much code 
> will actually break.
> 

I think it's a breaking change, just like flagging any obvious error 
case as a non-compilable error is a breaking change for code that wasn't 
aware of the problem.

I'm sure there was lots of code that did something equivalent to this 
before it was disallowed:

ref int foo()
{
   int x;
   return x;
}

That doesn't mean we shouldn't do it.

-Steve