Safer D first draft

[Dukc]

On Tuesday, 24 September 2024 at 19:23:57 UTC, Quirin Schroll 
wrote:
>
> Maybe `Expression.ptr` can be `@safe` if the compiler can 
> statically prove that `Expression` has non-zero length or is a 
> string literal (which is always zero-terminated).

I don't think that's a good idea.

First off, it makes it implementation-defined if a particular 
piece of code complies. When you have `someString.ptr`, It might 
be that compiler A figures out `someString` is never `""`, but 
compiler B doesn't. Therefore, A will accept it in a `@safe` 
function, B won't. Worse, if the function has attribute 
auto-inference, A and B will infer different attributes for the 
function, leading to confusing breakage when switching compilers.

Second, you can work around this by writing `&Expression[0]`. If 
the compiler could figure out that `Expression.ptr` would be 
safe, it can just as well figure out that bounds checks for 
`&Expression[0]` aren't needed.