Polyspace: expression must have a constant value
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Hello guys,
I have this C++17 code:
#define I2C_BUS_MAX_BUS_ITEMS 3
struct my_bus_t {
int bus{-1};
bool is_external;
};
static inline constexpr my_bus_t initBus(int bus)
{
my_bus_t ret{};
ret.bus = bus;
ret.is_external = false;
return ret;
}
constexpr my_bus_t buses[I2C_BUS_MAX_BUS_ITEMS] = {
initBus(1),
initBus(2),
};
This is the configuration setting.
It compiles well, but there is a problem in Polyspace: "expression must have a constant value".
Thank you in advance.
采纳的回答
You are initializing a three-element constexpr array with only two elements. If you change the line:
constexpr my_bus_t buses[I2C_BUS_MAX_BUS_ITEMS] = {
initBus(1),
initBus(2),
};
To something like:
constexpr my_bus_t buses[I2C_BUS_MAX_BUS_ITEMS] = {
initBus(1),
initBus(2),
initBus(2)
};
The error will go away. I am not sure why your compiler did not flag this.
3 个评论
Zulham Mr
2022-4-30
Anirban
2022-5-2
In this case, you have partially initialized the array. This is not an error by itself, and my guess is, that is why the compiler does not complain. If you try to initialize the uninitialized elements later, the compiler should show an error.
Indeed, Polyspace is being stricter than your compiler. But, as you can see, partially initializing a constexpr array is an error because it cannot be initialized fully later.
Zulham Mr
2022-5-3
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