emcc: error: undefined exported symbol: "_logBuffer" [-Wundefined] [-Werror]

I try to export some C++ function into wasm so that I can use it in web
any tips to troubleshoot this problem

**Version of emscripten/emsdk:**

emcc -v
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.37 (d02c29f95e9e68f2f50c2b0432c56a671814d5c8)
clang version 17.0.0 (https://github.com/llvm/llvm-project 86339ef088e9aac6cf52cf9022d7a5bd144d4c42)
Target: wasm32-unknown-emscripten
Thread model: posix

**Failing command line in full:**

emcc libiscrypt.a -s EXPORTED_FUNCTIONS="['_logBuffer']" -o test.html
emcc: warning: libiscrypt.a: archive is missing an index; Use emar when creating libraries to ensure an index is created [-Wemcc]
emcc: warning: libiscrypt.a: adding index [-Wemcc]
cache:INFO: generating system asset: symbol_lists/e4e80e56fde68f702424e267726dc300ef1ab1fa.json... (this will be cached in "/Users/yujie_wu/Documents/study/emsdk/upstream/emscripten/cache/symbol_lists/e4e80e56fde68f702424e267726dc300ef1ab1fa.json" for subsequent builds)
cache:INFO: - ok
emcc: error: undefined exported symbol: "_logBuffer" [-Wundefined] [-Werror]

when I use nm to check the whole symbol_list
nm libiscrypt.a
I can find __logBuffer
I have tried _logBuffer __logBuffer logBuffer
none succeed!

**Full link command and output with `-v` appended:**

I try to export some C++ function into wasm so that I can use it in web
any tips to troubleshoot this problem