System programming in D (Was: The God Language)

[Vladimir Panteleev]

On Wednesday, 4 January 2012 at 14:28:07 UTC, Andrei Alexandrescu 
wrote:
> Hmmm, I see that the other way around. D CTFE-generated macros 
> are much easier to debug because you can actually print the 
> code before mixing it in. If it looks like valid code... great.

Paging Don Clugston: would it be feasable to have the compiler 
remember the source position of every single char/string literal 
or compile-time-evaluated string expression?

I'm thinking that if the compiler tracks the source of every 
string/char literal in the source code, all across to any 
manipulations, debugging CTFE-generated code would be a lot 
easier - the compiler would emit error messages pointing inside 
string literals, and debuggers could step inside code in string 
literals. (The one thing this doesn't allow is allowing debuggers 
to step through a DSL with no D code in it.)

The naive implementation would store the position of every 
character, which would blow up the memory usage by about 13 times 
or so on 32-bit? (For every character, add a struct with 3 fields 
- char* filename; int line, column). A rope-like structure could 
cut down on that but possibly drastically complicating the 
implementation.