We need something like source_location in D

[Steven Schveighoffer]

On 7/30/19 9:39 PM, Andrej Mitrovic wrote:
>  From C++20: 
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1208r5.pdf
> 
> Instead of having to constantly declare "file = __FILE__, line = 
> __LINE__" everywhere, it would be so much more useful to just have a 
> single built-in type which we can default initialize . For example:
> 
> -----
> import std.algorithm;
> 
> void checkAndThrow (lazy bool expression, Loc loc = __LOCATION__)
> {
>      if (!expression)
>          throw new Exception("Failed", loc.file, loc.line);
> }
> 
> void main ()
> {
>      auto arr = [1, 1, 1, 1];
>      checkAndThrow(arr.sum == 4);
> 
>      // should throw with file+line of this statement
>      checkAndThrow(arr.sum == 5);
> }
> -----

This was my suggestion a while back:
https://issues.dlang.org/show_bug.cgi?id=18919

The biggest problem I see with using string and size_t is that those are 
common parameter types that can be confused with actual parameters. 
Having a Location type solves that.

-Steve