Merge pull request #227 from boostorg/refactoring_clean_code #561

Job	Run time
B2 gcc-11	4m 53s
CMake msvc-14.2 Debug C++17	5m 36s
CMake gcc-11 17 Debug	7m 33s
CMake msvc-14.2 Release C++17	8m 59s
B2 msvc-14.2	7m 24s
B2 clang-14	5m 50s
CMake gcc-11 20 Release	10m 12s
CMake msvc-14.3 Debug C++20	8m 40s
B2 msvc-14.3	8m 1s
CMake clang-11 17 Debug	5m 58s
CMake msvc-14.3 Release C++20	8m 36s
CMake clang-11 20 Debug	6m 31s
CMake clang-13 17 Release	8m 51s
CMake clang-13 20 Release	10m 23s
CMake clang-14 17 Debug -stdlib=libc++	7m 14s
CMake clang-14 20 Release -stdlib=libc++	11m 6s
	2h 5m 47s

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