In the 9498 issue there is a discussion about such code:

string[string] myValues;

ref string getValue(string v) {
   return myValues[v];
}

void main() {
   getValue("myValue") = "myString";
}

Currently it throws range violation as myValues[v] is regarged as rvalue (in Andrei's notion it is a read operation).

On the one hand, returning some value from AA array is a read operation which should throw as it happens with non-ref function. It is also impossible to know whether some new value would be assigned or just be copied like this:

string s = getValue(); // obviously read operation which need throw. tl;dr it does not really matter how value is returned, only whether is exists or not.

On the other hand, as original code shows, it could be write operation, so function should not throw.

Spec is silent about this and TDPL barely discusses it, let alone ref corner case.

Thoughts?

http://d.puremagic.com/issues/show_bug.cgi?id=9498

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