Bring back C++17 minimal requirement. (#475)

src/ftxui/component/animation.cpp

@@ -1,5 +1,4 @@
 #include <cmath>    // IWYU pragma: keep
-#include <compare>  // for operator<=, operator>=, partial_ordering
 #include <ratio>    // for ratio
 #include <utility>  // for move
 

src/ftxui/component/radiobox.cpp

@@ -26,8 +26,7 @@ class RadioboxBase : public ComponentBase {
   RadioboxBase(ConstStringListRef entries,
                int* selected,
                Ref<RadioboxOption> option)
-      : entries_(entries), selected_(selected), option_(std::move(option)) {
-  }
+      : entries_(entries), selected_(selected), option_(std::move(option)) {}
 
  private:
   Element Render() override {

src/ftxui/component/screen_interactive.cpp

@@ -1,7 +1,6 @@
-#include <algorithm>  // for min
+#include <algorithm>  // for copy, max, min
 #include <array>      // for array
-#include <chrono>  // for operator-, milliseconds, duration, operator<=>, time_point, common_type<>::type
-#include <compare>  // for operator>=, strong_ordering
+#include <chrono>  // for operator-, milliseconds, duration, operator>=, time_point, common_type<>::type
 #include <csignal>  // for signal, raise, SIGTSTP, SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, SIGTERM, SIGWINCH
 #include <cstdio>   // for fileno, size_t, stdin
 #include <ftxui/component/task.hpp>  // for Task, Closure, AnimationTask

src/ftxui/component/slider.cpp

@@ -266,12 +266,12 @@ Component Slider(ConstStringRef label,
                  ConstRef<int> min,
                  ConstRef<int> max,
                  ConstRef<int> increment) {
-  auto slider = Make<SliderBase<int>>(SliderOption<int>({
-      .value = value,
-      .min = min,
-      .max = max,
-      .increment = increment,
-  }));
+  SliderOption<int> option;
+  option.value = value;
+  option.min = min;
+  option.max = max;
+  option.increment = increment;
+  auto slider = Make<SliderBase<int>>(option);
   return Make<SliderWithLabel>(label, slider);
 }
 
@@ -280,12 +280,12 @@ Component Slider(ConstStringRef label,
                  ConstRef<float> min,
                  ConstRef<float> max,
                  ConstRef<float> increment) {
-  auto slider = Make<SliderBase<float>>(SliderOption<float>({
-      .value = value,
-      .min = min,
-      .max = max,
-      .increment = increment,
-  }));
+  SliderOption<float> option;
+  option.value = value;
+  option.min = min;
+  option.max = max;
+  option.increment = increment;
+  auto slider = Make<SliderBase<float>>(option);
   return Make<SliderWithLabel>(label, slider);
 }
 Component Slider(ConstStringRef label,
@@ -293,12 +293,12 @@ Component Slider(ConstStringRef label,
                  ConstRef<long> min,
                  ConstRef<long> max,
                  ConstRef<long> increment) {
-  auto slider = Make<SliderBase<long>>(SliderOption<long>({
-      .value = value,
-      .min = min,
-      .max = max,
-      .increment = increment,
-  }));
+  SliderOption<long> option;
+  option.value = value;
+  option.min = min;
+  option.max = max;
+  option.increment = increment;
+  auto slider = Make<SliderBase<long>>(option);
   return Make<SliderWithLabel>(label, slider);
 }
 

src/ftxui/screen/color.cpp

@@ -145,7 +145,7 @@ Color Color::RGB(uint8_t red, uint8_t green, uint8_t blue) {
 // static
 Color Color::HSV(uint8_t h, uint8_t s, uint8_t v) {
   if (s == 0) {
-    return {0,0,0};
+    return {0, 0, 0};
   }
 
   uint8_t region = h / 43;                                        // NOLINT