Fix type of length out parameter #2102

Job	Run time
build on ubuntu:23.10 (gcc,false)	1m 13s
build on ubuntu:23.10 (clang,false)	1m 24s
build on ubuntu:23.04 (gcc,false)	1m 21s
build on ubuntu:23.04 (clang,false)	1m 43s
build on ubuntu:22.04 (gcc,false)	1m 17s
build on ubuntu:22.04 (clang,true)	1m 29s
build on ubuntu:20.04 (gcc,false)	1m 24s
build on ubuntu:20.04 (clang,false)	1m 58s
build on ubuntu:18.04 (gcc,false)	1m 19s
build on ubuntu:16.04 (gcc,false)	1m 12s
build on ubuntu:14.04 (gcc,false)	1m 28s
build on debian:12 (gcc,false)	1m 19s
build on debian:12 (clang,false)	1m 32s
build on debian:11 (gcc,false)	1m 20s
build on debian:11 (clang,false)	1m 43s
build on fedora:38 (gcc, false)	1m 58s
build on debian:10 (gcc,false)	1m 17s
build on macos (macos-latest)	1m 36s
build on fedora:38 (clang, false)	2m 2s
build on macos (macos-latest-xlarge)	44s
build on fedora:37 (gcc, false)	8m 14s
build on fedora:37 (clang, false)	1m 58s
build on centos:7 (gcc, true)	1m 52s
run unit tests (ubuntu:22.04, clang)	13m 51s
run unit tests (centos:7, gcc)	10m 7s
	1h 5m 21s

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