A7-1-3: Triggered on static_cast

[nbusser]

Affected rules

• A7-1-3

Description

For some reason, A7-1-3 is triggered on basic varibales created from static_cast

Example

void false_positive() {
    std::uint8_t u8{0};

    auto const u32 = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning
    std::uint32_t const u32b = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning

    const auto u32c = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning
    const std::uint32_t u32d = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning
}

[lcartey]

Thanks for this report!

The following cases are false positives:

    auto const u32 = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning
    std::uint32_t const u32b = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning

    const auto u32c = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning

These are reported because we confuse the use of std::uint32_t in the cast with the potential use of std::uint_t in the variable declaration type. This can be adjusted.

The final case is interesting:

    const std::uint32_t u32d = static_cast<std::uint32_t>(u8); // Triggers A7-1-3 warning

std::uint32_t is a typedef, and the rule for A7-1-3 states:

CV-qualifiers shall be placed on the right hand side of the type that is a typedef or a using name.

So, strictly speaking this is a true positive. However, the rule contradicts itself, because it later gives this example as compliant:

void Fn(const std::uint8_t& input) // Compliant

I don't know whether they just forgot std::uint8_t was a typedef, or they intended to suggest an exclusion for standard library types but it's not clearly called out, so, for now, we're sticking with the strict definition of the rule.

[nbusser-sr]

Interesting! Thanks for the feedback