Stop using C++ auto to assign results of arithmetic operations #4573

Job	Run time
ci (ubuntu-20.04, gcc, g++, 20, Release)	7m 48s
ci (ubuntu-20.04, gcc, g++, 20, Debug)	7m 36s
ci (ubuntu-20.04, clang, clang++, 20, Release)	8m 15s
ci (ubuntu-20.04, clang, clang++, 20, Debug)	6m 56s
ci (ubuntu-22.04, gcc, g++, 20, Release)	7m 13s
ci (ubuntu-22.04, gcc, g++, 20, Debug)	6m 38s
ci (ubuntu-22.04, clang, clang++, 20, Release)	8m 48s
ci (ubuntu-22.04, clang, clang++, 20, Debug)	7m 40s
ci (macos-12, gcc, g++, 20, Release)	13m 27s
ci (macos-12, gcc, g++, 20, Debug)	17m 4s
ci (macos-14, clang, clang++, 20, Release)	5m 6s
ci (macos-14, clang, clang++, 20, Debug)	4m 12s
ci (windows-2022, cl, cl, 20, Release)	7m 40s
ci (windows-2022, cl, cl, 20, Debug)	6m 28s
	1h 54m 51s

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