Various cleanup

Some of them were clang-tidy messages, some compiler warnings.

.clang-tidy

@@ -30,6 +30,7 @@ Checks: '
     -misc-include-cleaner,
     -modernize-use-trailing-return-type,
     -modernize-use-designated-initializers,
+    -portability-avoid-pragma-once,
     -readability-identifier-length,
     -readability-isolate-declaration,
     -readability-magic-numbers,

src/core/include/mp-units/ext/inplace_vector.h

@@ -76,7 +76,7 @@ public:
   constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(cend()); }
   constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(cbegin()); }
 
-  [[nodiscard]] constexpr bool empty() const noexcept { return size() == 0; };
+  [[nodiscard]] constexpr bool empty() const noexcept { return size() == 0; }
   [[nodiscard]] constexpr size_type size() const noexcept { return size_; }
   [[nodiscard]] static constexpr size_type max_size() noexcept { return N; }
   [[nodiscard]] static constexpr size_type capacity() noexcept { return N; }

src/core/include/mp-units/framework/dimension.h

@@ -43,7 +43,6 @@
 #ifdef MP_UNITS_IMPORT_STD
 import std;
 #else
-#include <array>
 #include <cstdint>
 #include <iterator>
 #include <string_view>
@@ -69,13 +68,13 @@ struct dimension_interface {
   template<Dimension Lhs, Dimension Rhs>
   [[nodiscard]] friend consteval Dimension auto operator*(Lhs, Rhs)
   {
-    return expr_multiply<derived_dimension, struct dimension_one>(Lhs{}, Rhs{});
+    return expr_multiply<derived_dimension, dimension_one>(Lhs{}, Rhs{});
   }
 
   template<Dimension Lhs, Dimension Rhs>
   [[nodiscard]] friend consteval Dimension auto operator/(Lhs, Rhs)
   {
-    return expr_divide<derived_dimension, struct dimension_one>(Lhs{}, Rhs{});
+    return expr_divide<derived_dimension, dimension_one>(Lhs{}, Rhs{});
   }
 
   template<Dimension Lhs, Dimension Rhs>

src/core/include/mp-units/framework/quantity_spec.h

@@ -46,7 +46,6 @@ import std;
 #include <concepts>
 #include <cstdint>
 #include <optional>
-#include <tuple>
 #include <type_traits>
 #endif
 #endif
@@ -181,7 +180,7 @@ struct quantity_spec_interface_base {
   [[nodiscard]] friend consteval QuantitySpec auto operator*(Lhs lhs, Rhs rhs)
   {
     return detail::clone_kind_of<Lhs{}, Rhs{}>(
-      detail::expr_multiply<derived_quantity_spec, struct dimensionless, type_list_of_quantity_spec_less>(
+      detail::expr_multiply<derived_quantity_spec, dimensionless, type_list_of_quantity_spec_less>(
         detail::remove_kind(lhs), detail::remove_kind(rhs)));
   }
 
@@ -189,7 +188,7 @@ struct quantity_spec_interface_base {
   [[nodiscard]] friend consteval QuantitySpec auto operator/(Lhs lhs, Rhs rhs)
   {
     return detail::clone_kind_of<Lhs{}, Rhs{}>(
-      detail::expr_divide<derived_quantity_spec, struct dimensionless, type_list_of_quantity_spec_less>(
+      detail::expr_divide<derived_quantity_spec, dimensionless, type_list_of_quantity_spec_less>(
         detail::remove_kind(lhs), detail::remove_kind(rhs)));
   }
 

src/core/include/mp-units/framework/symbol_text.h

@@ -61,7 +61,7 @@ constexpr bool is_basic_literal_character_set_char(char ch)
 {
   // https://en.cppreference.com/w/cpp/language/charset
   return ch == 0x00 || (0x07 <= ch && ch <= 0x0D) || (0x20 <= ch && ch <= 0x7E);
-};
+}
 
 template<typename InputIt>
 constexpr bool is_basic_literal_character_set(InputIt begin, InputIt end) noexcept

src/core/include/mp-units/framework/symbolic_expression.h

@@ -161,7 +161,7 @@ template<typename T>
     return T::exponent;
   else
     return ratio{1};
-};
+}
 
 template<SymbolicArg T, ratio R>
 [[nodiscard]] consteval auto power_or_T_impl()

src/core/include/mp-units/framework/unit.h

@@ -184,7 +184,7 @@ struct unit_interface {
   template<Unit Lhs, Unit Rhs>
   [[nodiscard]] friend MP_UNITS_CONSTEVAL Unit auto operator*(Lhs lhs, Rhs rhs)
   {
-    return expr_multiply<derived_unit, struct one>(lhs, rhs);
+    return expr_multiply<derived_unit, one>(lhs, rhs);
   }
 
   /**
@@ -195,7 +195,7 @@ struct unit_interface {
   template<Unit Lhs, Unit Rhs>
   [[nodiscard]] friend MP_UNITS_CONSTEVAL Unit auto operator/(Lhs lhs, Rhs rhs)
   {
-    return expr_divide<derived_unit, struct one>(lhs, rhs);
+    return expr_divide<derived_unit, one>(lhs, rhs);
   }
 
   template<Unit Lhs, Unit Rhs>