Specify the context type for the index in an increment/decrement operation #2271
Description
The context type for an expression of the form e1[e2]++, e1[e2]--, ++e1[e2], --e1[e2] is apparently not specified.
In the case where the corresponding operator declarations have parameter types T1 and T2 for the index, the most general type that would work is the greatest lower bound of T1 and T2, so we would most likely use the standard lower bound (which is an approximation of the greatest lower bound).
class C {
T0 operator[](T1 index) ...
operator[]=(T2 index, T3 value) ...
}
X whatever<X>() {
print(X);
throw 0;
}
void main() {
C()[whatever()]++; // Prints the standard lower bound of `T1` and `T2`.
}