clang-tidy: modernize-concat-nested-namespaces (NFC)

wpimath/src/main/native/include/units/constants.h

@@ -43,13 +43,7 @@
 #include "units/time.h"
 #include "units/velocity.h"
 
-namespace units {
-/**
- * @brief namespace for physical constants like PI and Avogadro's Number.
- * @sa See unit_t for more information on unit type containers.
- */
-#if !defined(DISABLE_PREDEFINED_UNITS)
-namespace constants {
+namespace units::constants {
 /**
  * @name Unit Containers
  * @anchor constantContainers
@@ -105,6 +99,4 @@ static constexpr const unit_t<
           (15 * math::cpow<3>(h) * math::cpow<2>(c) *
            math::cpow<4>(N_A)));  ///< Stefan-Boltzmann constant.
 /** @} */
-}  // namespace constants
-#endif
-}  // namespace units
+}  // namespace units::constants

wpimath/src/main/native/include/units/math.h

@@ -34,7 +34,6 @@
 #include "units/base.h"
 #include "units/dimensionless.h"
 
-namespace units {
 //----------------------------------
 // UNIT-ENABLED CMATH FUNCTIONS
 //----------------------------------
@@ -45,7 +44,7 @@ namespace units {
  *          rounding functions, etc.
  * @sa See `unit_t` for more information on unit type containers.
  */
-namespace math {
+namespace units::math {
 //----------------------------------
 // TRIGONOMETRIC FUNCTIONS
 //----------------------------------
@@ -772,5 +771,4 @@ constexpr units::radian_t NormalizeAngle(units::radian_t theta) {
 
   return theta;
 }
-}  // namespace math
-}  // namespace units
+}  // namespace units::math