Tips from the compiler

[Don]

Rainer Deyke wrote:
> On 10/19/2010 05:44, Don wrote:
>> Rainer Deyke wrote:
>>> Simple.  If the template is in a library file, it's library code,
>>> regardless of where it was instantiated.
>> The separation isn't clean. User code instantiates library code which
>> instantiates user code. Look at std.algorithm, for example.
>> Mixins and template alias parameters blur things even further.
> 
> There are exactly four possible situations:
>   - Template in library code instantiated by library code.
>   - Template in library code instantiated by user code.
>   - Template in user code instantiated by library code.
>   - Template in user code instantiated by user code.
> 
> These cases can be nested arbitrarily deep, but that doesn't add
> additional cases.  If we categorically ignore where a template is
> instantiated, the four cases reduce to just two:
>   - Template in library code.
>   - Template in user code.

Don't forget that delegate literals can be passed as template alias 
parameters; so can expressions. Problems get even more extreme when 
mixins are involved.

Example: Suppose we have warnings for possible numeric overflow. Then 
consider:
sort!"a*5<b"(x);
We should have a warning that 'a*5' may cause a numeric overflow. How 
can that be done?