Fix various warnings detected with msvc17 #839

Job	Run time
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 11)	16m 55s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 14)	18m 2s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 17)	18m 29s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 11)	17m 4s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 14)	15m 39s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 17)	17m 11s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 11)	18m 47s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 14)	18m 48s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 17)	20m 55s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 11)	14m 5s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 14)	13m 59s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 17)	15m 46s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 11)	15m 9s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 14)	15m 33s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 17)	16m 45s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 11)	19m 36s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 14)	20m 38s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 17)	21m 58s
	5h 15m 19s

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