2.4.0

• (!) feat: phase_velocity and group_velocity aliases removed from ISQ by ISO
• feat: iec::bit using-declared in iec::unit_symbols
• feat: common unit symbols now use EQUIV{u1, u2, ...} syntax
• feat: scaled_unit symbol printing improved ([] around the entire unit, small magnitude values do not use a power of 10 anymore)
• feat: scaled_unit does not have a priority over derived_unit anymore
• feat: fractional exponents support added to mag_power
• feat: tag types are now required to be empty
• feat: magnitude text now obeys formatting parameters and knows how to print constants
• feat: added support for printing powers of magnitude constants
• feat: SymbolicConstant concept added
• feat: common_unit selection algorithm improved to make rev + rad return rad
• feat: litre text symbol changed from l to L to avoid ambiguity with 1
• feat: alternative litre unit symbol L added to prevent ambiguities with 1
• feat: Unicode unit symbols
• feat: π added as an alias for pi
• feat: expr_pow extended to remove redundancy in callers
• feat: DerivedDimensionExpr, DerivedQuantitySpecExpr and DerivedUnitExpr removed
• feat: MagnitudeSpecExpr and PowerVBase removed and some functions renamed to limit possible ambiguity in overload resolution
• feat: std::is_object constraint applied to value_type_t
• feat: quantity_values are now defined on top of std::chrono::duration_values
• feat: from now on truncation is not allowed in compound assignment
• feat(example): currency example now uses chrono::time_point and has better interfaces
• feat(example): treat_as_floating_point specializations for examples' types removed
• (!) refactor: all iec quantity specifications are now deprecated and moved to isq
• (!) refactor: mag_constant now takes a symbol and a value and the class deriving from it must be final
• (!) refactor: op==(U1, U2) now checks for the same type (old behavior available as equivalent(U1, U2)) + convertible now verifies associated quantity_spec as well
• (!) refactor: ascii -> portable, unicode -> utf8, 'A' -> 'P'
• (!) refactor: char_traits removed from fixed_string
• (!) refactor: convertibility traits and concepts refactored to use bool flags instead of wrappers
• (!) refactor: tag types should not expose their members
• refactor: convertible(U1, U2) implementation simplified
• refactor: abs moved to constexpr_math.h
• refactor: unit_symbol_impl simplified
• refactor: unit_symbol_formatting moved to a dedicated header file
• refactor: shorten_T removed
• refactor: magnitude interface cleanup
• refactor: derived_from_the_same_base_dimension no longer needed
• refactor: one_of usage removed from the fixed_string deduction guides
• refactor: quantity.h is not needed in constants.h (unit.h is enough)
• refactor: SameDimension concept is not needed and can be inlined in DimensionOf
• refactor: framework Unicode symbols are now spelled using their codes
• refactor: QuantitySpecWithNoSpecifiers removed and kind_of definition simplified
• refactor: treat_as_floating_point simplified and extended to use std::chrono::treat_as_floating_point_v
• refactor: wrapped_type_t reuses std::indirectly_readable_traits
• refactor: expr_fractions takes direct OneType type now instead of a trait
• refactor: Unicode symbols description reworked based on the latest SG16 recommendations
• refactor: Mutable concept applied to quantity and quantity_point
• refactor: explicit cleanup for deduction guides of quantity and quantity_point
• refactor: point_origin_interface::op- cleanup
• refactor: QuantityLikeImpl refactored to conform to API Reference by @JohelEGP
• refactor: get_complexity refactored to be 0-based and not account for a number of arguments in a list
• refactor: get_complexity refactored to returned maximum complexity of an element (instead of the sum of elements)
• refactor(test): derived_quantity refactored to child_quantity
• fix: missing are_ingredients_convertible overloads added
• fix: constraints for magnitude added for scaled_unit and fixed common_unit instantiating it incorrectly
• fix: according to ISO 80000-16 % should always be prefixed with space
• fix: extraneous space in unit symbol having only denominators removed
• fix: explicit cast added to less for magnitudes to fix clang-arm64 conversion error
• fix: common_unit handling fixed for some corner cases
• fix: math functions constraints fixed
• fix: operator*(M, U u) fixed for U being scaled_unit
• fix: subsumption of QuantityKindSpec fixed
• fix: ValuePreservingTo fixed to apply std::remove_cvref_t on FromRep
• fix: compound assignment operations on quantities now behave the same as on the underlying representation types
• fix: QuantityConvertibleTo used in quantity_point compound assignment
• fix: convertible_kinds implementation fixed
• fix(tests): freestanding build fixed
• test: unit tests for the inverse of mag_constant added
• test: Unicode symbols used in unit tests
• test: more std::chrono tests added
• test: commutativity tests added to ISQ
• test: one kind_of test added to reference tests
• test: pow<0> and pow<1> tests added for dimensions
• test: more get_common_quantity_spec tests added
• build: setting of some test_package CMake options enabled only for a cxx_modules build
• ci: sudo apt update added for documentation.yml in hope that it will resolve missing system packages issue
• ci: MSVC added to the CI
• ci: the latest not-released docs will use "HEAD" as a version from now on
• ci: documentation action should run on a new tag as well
• ci: documentation action limited only to commits that change documentation files
• ci: non-documentation actions should not run on tags
• docs: missing systems added to the "Project Structure" chapter
• docs: graphs of ISQ kind hierarchies improved
• docs: category of the ISO meeting reports changed to "WG21 Updates"
• docs: blog comments support added
• docs: Part 1-5 articles of the ISQ series added
• docs: "Symbols of scaled units" chapter added + minor updates to scaled and common units chapters
• docs: conan profile updated to present gcc-14 instead of gcc-12 which is no longer supported
• docs: "Why derived units order is not preserved from the multiplication?" chapter added to FAQ
• docs: "Many shades of the same unit" extended with a note about the derived units order
• docs: API Reference now presents index.html instead of full.hml