Require more precise type resolution in binary operation

[katat]

In type checking phase, the type of a binary operation expression is only determined by the left hand side:

noname/src/type_checker/checker.rs

Line 389 in a2d31f7

Op2::Addition

However, in the following case, it can mistakenly seen a non constant expression as constant;

fn is_not_constant(val: Field) -> Field {
    // val can be non constant
    return 1 + val;
}

1 + val can be a non constant field type as val can be a non constant.
Therefore, when computing the types for the binary operations, it should take cares of the both sides.

[mimoo]

mmm interesting, wondering if that means that "constant" shouldn't be in the type

[katat]

yeah, I think we still need to propagate whether it is a constant or not. For example, the functions support const attribute that enforce the argument to be constant.