ArithmeticConversion

pub fn ArithmeticConversion(comptime A: type, comptime B: type) type

File

Code

pub fn ArithmeticConversion(comptime A: type, comptime B: type) type {
    if (A == c_longdouble or B == c_longdouble) return c_longdouble;
    if (A == f80 or B == f80) return f80;
    if (A == f64 or B == f64) return f64;
    if (A == f32 or B == f32) return f32;

    const A_Promoted = PromotedIntType(A);
    const B_Promoted = PromotedIntType(B);
    comptime {
        std.debug.assert(integerRank(A_Promoted) >= integerRank(c_int));
        std.debug.assert(integerRank(B_Promoted) >= integerRank(c_int));
    }

    if (A_Promoted == B_Promoted) return A_Promoted;

    const a_signed = @typeInfo(A_Promoted).int.signedness == .signed;
    const b_signed = @typeInfo(B_Promoted).int.signedness == .signed;

    if (a_signed == b_signed) {
        return if (integerRank(A_Promoted) > integerRank(B_Promoted)) A_Promoted else B_Promoted;
    }

    const SignedType = if (a_signed) A_Promoted else B_Promoted;
    const UnsignedType = if (!a_signed) A_Promoted else B_Promoted;

    if (integerRank(UnsignedType) >= integerRank(SignedType)) return UnsignedType;

    if (std.math.maxInt(SignedType) >= std.math.maxInt(UnsignedType)) return SignedType;

    return ToUnsigned(SignedType);
}