link waring when using '-Wl, -dead_strip'

Question

using '-Wl, -dead_strip' can remove functions and data that are unreachable by the entry point or exported symbols. When I add '-Wl, -dead_strip' for link, got a warning: warning: cannot find entry symbol ad-strip; defaulting to 000000008000003c and the unsed function symbol is not found in target file, which is I wanted.

I want to know how to elimate the waring

I have using --function-section for compile, and -gc-sections for link, however, some functions symbol not needed are still in target file. After add '-Wl, -dead_strip', it works, but I got the warning,"warning: cannot find entry symbol ad-strip; defaulting to 000000008000003c."