Make const, immutable, inout, and shared illegal as function attributes on the left-hand side of a function

[Walter Bright via Digitalmars-d]

On 10/9/2014 1:50 AM, Martin Nowak wrote:
> Kenji just proposed a slightly controversial pull request so I want to reach out
> for more people to discuss it's tradeoffs.
> It's about deprecating function qualifiers on the left hand side of a function.

This has come up before, and has been debated at length.

const is used both as a storage class and as a type constructor, and is 
distinguished by the grammar:

    const(T) v; // type constructor, it affects the type T

    const T v;  // storage class, affects the symbol v and the type of v

In particular,

    const T *v;

does not mean:

    const(T)* v;

For functions, const-as-storage-class applies to the function symbol. And if it 
is misused, the compiler will very likely complain about a mismatched type.
Breaking this adds a special case inconsistency, besides breaking existing code.

(I understand that there's a lot of advocacy lately about "break my code", but 
I'm the one who bears the brunt of "you guys broke my code again, even though 
the code was correct and worked perfectly well! D sux.", besides, of course, 
those poor souls who have to go fix their code base, and I hear again about how 
D is unstable, another Reddit flame-fest about D being unsuitable because the 
designers can't make up their mind, etc.)

This endless search for the ideal syntax is consuming our time while we aren't 
working on issues that matter. (And this change will consume users' time, too, 
not just ours.)

If we're going to break things, it needs to be for something that matters. This 
doesn't make the cut.