modernize-use-std-numbers¶
Finds constants and function calls to math functions that can be replaced
with C++20’s mathematical constants from the numbers header and offers
fix-it hints.
Does not match the use of variables with that value, and instead,
offers a replacement for the definition of those variables.
Function calls that match the pattern of how the constant is calculated are
matched and replaced with the std::numbers constant.
The use of macros gets replaced with the corresponding std::numbers
constant, instead of changing the macro definition.
The following list of constants from the numbers header are supported:
- e
- log2e
- log10e
- pi
- inv_pi
- inv_sqrtpi
- ln2
- ln10
- sqrt2
- sqrt3
- inv_sqrt3
- egamma
- phi
The list currently includes all constants as of C++20.
The replacements use the type of the matched constant and can remove explicit
casts, i.e., switching between std::numbers::e,
std::numbers::e_v<float> and std::numbers::e_v<long double> where
appropriate.
double sqrt(double);
double log2(double);
void sink(auto&&) {}
void floatSink(float);
#define MY_PI 3.1415926
void foo() {
    const double Pi = 3.141592653589;           // const double Pi = std::numbers::pi
    const auto Use = Pi / 2;                    // no match for Pi
    static constexpr double Euler = 2.7182818;  // static constexpr double Euler = std::numbers::e;
    log2(exp(1));                               // std::numbers::log2e;
    log2(Euler);                                // std::numbers::log2e;
    1 / sqrt(MY_PI);                            // std::numbers::inv_sqrtpi;
    sink(MY_PI);                                // sink(std::numbers::pi);
    floatSink(MY_PI);                           // floatSink(std::numbers::pi);
    floatSink(static_cast<float>(MY_PI));       // floatSink(std::numbers::pi_v<float>);
}
Options¶
- DiffThreshold¶
- A floating point value that sets the detection threshold for when literals match a constant. A literal matches a constant if - abs(literal - constant) < DiffThresholdevaluates to- true. Default is 0.001.
- IncludeStyle¶
- A string specifying which include-style is used, llvm or google. Default is llvm.