tidy - modernize-use-std-numbers — Extra Clang Tools 22.0.0git documentation (original) (raw)

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::numbersconstant, 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:🔢:e,std:🔢:e_v<float> and std:🔢: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:🔢:pi const auto Use = Pi / 2; // no match for Pi static constexpr double Euler = 2.7182818; // static constexpr double Euler = std:🔢:e;

log2(exp(1));                               // std:🔢:log2e;
log2(Euler);                                // std:🔢:log2e;
1 / sqrt(MY_PI);                            // std:🔢:inv_sqrtpi;
sink(MY_PI);                                // sink(std:🔢:pi);
floatSink(MY_PI);                           // floatSink(std:🔢:pi);
floatSink(static_cast<float>(MY_PI));       // floatSink(std:🔢: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 ifabs(literal - constant) < DiffThreshold evaluates to true. Default is 0.001.

IncludeStyle¶

A string specifying which include-style is used, llvm or google. Default is llvm.