Re: Re: Setting positions for annotation generated trees

Hi Eugene,

it's actually a pretty straightforward problem and my current solution 
works really well.
The use case is an annotated object containing several case classes as 
schematic for database/app models that are expanded into several classes 
and objects each. The original tree is discarded completely, so 
effectively, I'm turning a single file into another, which contains a 
single object hosting all of the model classes.
Just before the final reification, I simple recurse into the result tree 
and set the offset by calculating the child tree size using 
'showCode().length', then applying a crude heuristic to handle templates 
and other internal structures.
This yields adequate precision for error messages, but I assume that the 
compiler must be capable of doing that perfectly.
I actually just thought about just discarding the macro expansion and 
compiling the file containing the debug output as regular source; that 
ought to be the pragmatic approach…

On Monday, 17 August 2015 00:58:57 UTC+2, Eugene Burmako wrote:
>
> Hi!
>
> Good error messages for macro expansions are hard, because it's usually 
> hard to automatically classify/position parts of expansions. However, it 
> might very well be that there's a heuristics that works for an important 
> class of use cases.
>
> Could you give an example of how you would the compiler to calculate the 
> positions for your use case? 
>
> Cheers,
> Eugene
>
> On 16 August 2015 at 18:07, Torsten Schmits <[email protected] 
> <javascript:>> wrote:
>
>>
>> update 2: Noticed that I could cast internal.util.Position to 
>> c.universe.Position, and similarly for SourceFile.
>> Creating those from scratch led to a completely satisfactory result, 
>> although using `atPos` somehow screws it up, while it works great when 
>> reflecting `setPos`.
>> Anyhoo, I still have to calculate the positions manually, would be nice 
>> to have this done by the compiler.
>>
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