[Issue 13981] std.algorithm: inconsistent handling of static arrays

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13981

--- Comment #1 from markus at oberhumer.com ---
As metaprogramming in D is so much fun (esp. when coming from C++), I've hacked
together some experimental code.

Remember that I'm a D newcomer, so please be gentle :-)


// dmd 2.066.1
import std.algorithm, std.traits;

private auto _rangeForStaticArray(R)(const ref R r)
if (isStaticArray!R) {
    // pseudo code - no idea if it is possible to express hasHeapStorage!R or
hasStackStorage!R
    // - could also test for immutable, but no sure if that's the correct
semantics ?
    // - could also test for something like isGC!R ???
    static if (1 || hasHeapStorage!R) {
        return r[]; // safe
    } else static if (hasStackStorage!R) {
        static assert(false, "stack storage for static array not allowed - pass
a slice");
        return r[]; // possibly unsafe ???
    } else {
        static assert(false, "unknown storage for static array - pass a
slice");
    }
}

auto sum(R)(const ref R r)
if (isStaticArray!R) {
    return std.algorithm.sum(_rangeForStaticArray(r));
}
auto sum(R)(R r)
if (!isStaticArray!R) {
    return std.algorithm.sum(r);
}

void test_dynamic_array() {
    int[] arr1 = [1, 2, 3, 4, 5];
    immutable int[] arr2 = [1, 2, 3, 4, 5];

    sum(arr1);                  // OK
    sum(arr2);                  // OK
}

void test_static_array() {
    int[5] arr1 = [1, 2, 3, 4, 5];
    immutable int[5] arr2 = [1, 2, 3, 4, 5];

    sum(arr1);                  // seems OK
    sum(arr2);                  // seems OK
}

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