Fix #14796: FP assertWithSideEffect for member functions without definition #20304

Job	Run time
build_cmake (alpine:3.23, false, false)	3m 29s
build_make (alpine:3.23)	5m 57s
build_make (ubuntu:25.10)	4m 52s
build_make (ubuntu:24.04)	4m 37s
build_cmake (ubuntu:25.10, true, true)	3m 0s
build_cmake (ubuntu:24.04, true, true)	5m 49s
	27m 44s

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