c++11 error message when compiling c++14

fcarney

I am using literals from c++14 in my code:

// c++11
constexpr long double operator"" _m(long double m){
    assert(m >= 0.0l && m < 10.0l); // c++14
    return m;
}
constexpr long double operator"" _s(long double s){
    return s;
}


// c++14
constexpr long double operator""m(long double m){
    return m;
}
constexpr long double operator""s(long double s){
    return s;
}

I have changed my compiler setting in my pro file:

CONFIG += c++14

I get this error/warning:

C:\Users\\Documents\programming\testing\test_rules\testrules.h:18: error: invalid suffix on literal; C++11 requires a space between literal and identifier

Is there a way to suppress this error when compiling c++14?
BTW, it still seems to compile correctly. It just throws an error.

For reference.

hskoglund

Hi, if your code isn't inside a standard library header you'll still need that _ prefix even for c++14, i.e. perhaps try:

// c++14
constexpr long double operator""_m(long double m){
    return m;
}
constexpr long double operator""_s(long double s){
    return s;
}

fcarney

@hskoglund said in c++11 error message when compiling c++14:

Hi, if your code isn't inside a standard library header you'll still need that _ prefix even for c++14

Why would being in a standard library have any effect on using a literal as defined in c++14? The examples from CppCoreGuidelines show this exact example of using m and s. The point is to show intent through liberal use of literals. Where does it say you have to use underscores? I didnt see that in the other link I provided. Confused...

Maybe I was not clear: The code compiles just fine and runs just fine. It is Qt Creator complaining when there is actually no compilation error.

fcarney

Crap, it does say this:

may only appear as part of a standard library header

That is strange. Thanks for the heads up.

fcarney

Just as @hskoglund said all error messages go away if doing only this:

constexpr long double operator""_m(long double m){
    assert(m >= 0.0l && m < 100.0l); // c++14
    return m;
}
constexpr long double operator""_s(long double s){
    return s;
}

Note no spaces between " and _. Darn reserved names and stuff!

koahnig

@fcarney

Are talking about the "code model" warnings/errors in qt creator?

You can change it under "Tools"->"Options"->"{} C++"->"Code Model"
Under "Diagnostic Configuration" you can choose another configuration or adjust the one used. The same syntax can be used as you would in suppressing warnings for compilation.