Eliminate all references to M_PI.

OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj

@@ -7219,7 +7219,6 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				BUNDLE_LOADER = "$(TEST_HOST)";
-				CLANG_CXX_LANGUAGE_STANDARD = "c++17";
 				CLANG_ENABLE_MODULES = YES;
 				"CODE_SIGN_IDENTITY[sdk=macosx*]" = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;
@@ -7237,7 +7236,6 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				BUNDLE_LOADER = "$(TEST_HOST)";
-				CLANG_CXX_LANGUAGE_STANDARD = "c++17";
 				CLANG_ENABLE_MODULES = YES;
 				"CODE_SIGN_IDENTITY[sdk=macosx*]" = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;

OSBindings/Mac/Clock SignalTests/OPLTests.mm

@@ -11,6 +11,7 @@
 #include "Tables.hpp"
 
 #include <cmath>
+#include <numbers>
 
 @interface OPLTests: XCTestCase
 @end
@@ -24,7 +25,7 @@
 		const auto logSin = Yamaha::OPL::negative_log_sin(c);
 		const auto level = Yamaha::OPL::power_two(logSin);
 
-		double fl_angle = double(c) * M_PI / 512.0;
+		double fl_angle = double(c) * std::numbers::pi_v<double> / 512.0;
 		double fl_level = sin(fl_angle);
 
 		XCTAssertLessThanOrEqual(fabs(fl_level - double(level) / 4096.0), 0.01, "Sine varies by more than 0.01 at angle %d", c);

Outputs/OpenGL/ScanTargetGLSLFragments.cpp

@@ -9,10 +9,7 @@
 #include "ScanTarget.hpp"
 
 #include <cmath>
-
-#ifndef M_PI
-#define M_PI 3.1415926f
-#endif
+#include <numbers>
 
 using namespace Outputs::Display::OpenGL;
 
@@ -37,7 +34,7 @@ void ScanTarget::set_uniforms(ShaderType type, Shader &target) const {
 			for(int c = 0; c < 4; ++c) {
 				GLfloat angle = (GLfloat(c) - 1.5f) / 4.0f;
 				texture_offsets[c] = angle * clocks_per_angle;
-				angles[c] = GLfloat(angle * 2.0f * M_PI);
+				angles[c] = GLfloat(angle * 2.0f * std::numbers::pi_v<float>);
 			}
 			target.set_uniform("textureCoordinateOffsets", 1, 4, texture_offsets);
 			target.set_uniform("compositeAngleOffsets", 4, 1, angles);
@@ -70,7 +67,7 @@ void ScanTarget::set_sampling_window(int output_width, int, Shader &target) {
 		GLfloat angles[4];
 		for(int c = 0; c < 4; ++c) {
 			texture_offsets[c] = 1.0f * (((one_pixel_width * float(c)) / 3.0f) - (one_pixel_width * 0.5f));
-			angles[c] = GLfloat((texture_offsets[c] / clocks_per_angle) * 2.0f * M_PI);
+			angles[c] = GLfloat((texture_offsets[c] / clocks_per_angle) * 2.0f * std::numbers::pi_v<float>);
 		}
 		target.set_uniform("textureCoordinateOffsets", 1, 4, texture_offsets);
 		target.set_uniform("compositeAngleOffsets", 4, 1, angles);

SignalProcessing/FIRFilter.cpp

@@ -9,13 +9,9 @@
 #include "FIRFilter.hpp"
 
 #include <cmath>
+#include <numbers>
 #include <numeric>
 
-#ifndef M_PI
-static constexpr float M_PI = 3.1415926f;
-// TODO: use std::numbers::pi_v when switching to C++20.
-#endif
-
 using namespace SignalProcessing;
 
 /*
@@ -134,7 +130,7 @@ FIRFilter::FIRFilter(
 	std::vector<float> A(Np+1);
 	A[0] = 2.0f * (high_frequency - low_frequency) / input_sample_rate;
 	for(unsigned int i = 1; i <= Np; ++i) {
-		const float i_pi = float(i) * float(M_PI);
+		const float i_pi = float(i) * std::numbers::pi_v<float>;
 		A[i] =
 			(
 				sinf(two_over_sample_rate * i_pi * high_frequency) -