Re: ++x vs. atomicOp!"+="(x,1) with a shared int

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On Sunday, 1 June 2014 at 07:06:27 UTC, Chuck Allison wrote:

I was under the impression that calling ++x for a shared x is an error. Not only do I not get an error, the effect of ++x is identical to atomicOp"+="(x,1) in the following example (the variable is count here, not x):

shared int count;

void f(string s) {
    foreach (i; 0..100)
        writefln("%s: %s", ++count, s);
}

void main() {
    spawn(&f,"Dessert Topping");
    spawn(&f,"Floor Wax");
}

I get the same results if I change f like so:

void f(string s) {
    foreach (i; 0..100) {
        atomicOp!"+="(count,1);
        writefln("%s: %s", count, s);
    }
}

Is ++ now atomic for shared ints? I'm just wondering why the first version of f works at all, when TDPL says it should be an error.

Thanks.

It is a known bug with an open pull request to fix it.

https://github.com/D-Programming-Language/dmd/pull/3070