Inherent code performance advantages of D over C?

[Walter Bright]

On 12/8/2013 2:13 AM, Araq wrote:
> From this list only (7) is a valid point. All the others can be trivially dealt
> with whole program optimization (1,2,3)

If it's trivial, it's not happening. (1) would require solving the halting 
problem. (2) is impractical because there's no way for the programmer to detect 
if his call stack is pure or not, so he can't reasonably fix it to make it pure. 
(3) does require whole program analysis, which is done (as I said) by the 
linker, and is not normally done. Will gcc/ld do it? Nope. (It's not so trivial.)

> or coding conventions (4,5,6) (always
> pass a (char*, len) pair around for efficient slicing).

(4) just try retrofitting an existing C program to do this. I have. You'll give 
it up soon :-)

(5) it just doesn't happen in C code - it's too hard

(6) I pretty much never see this happening in real C code - it's not so trivial


> Interestingly, things
> that are encouraged in Ada (this is an array of integers of range 0..30, see
> value range propagation) are much harder to recompute with whole program
> optimization and D lacks them.

You can do these in D with a library type.