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) < DiffThreshold
evaluates totrue
. Default is 0.001.
- IncludeStyle¶
A string specifying which include-style is used, llvm or google. Default is llvm.