which memory dynamic-linking libraries should use for host functions?

https://github.com/WebAssembly/WASI/blob/main/legacy/application-abi.md says:

Regardless of the kind, all modules accessing WASI APIs also export a linear memory with the name memory. Data pointers in WASI API calls are relative to this memory's index space.

i guess it's the convention used by many of host functions, not only WASI.

however, wasi-libc's libc.so doesn't export "memory".

actually, wasm-ld rejects -shared -export-memory.
https://github.com/llvm/llvm-project/blob/06a808c4f4014edfeb2517bddd0bcb63eb4a260b/lld/wasm/Driver.cpp#L658

am i missing something?

a. wasm-ld should be fixed.

b. application-abi.md doesn't apply to a module which is a shared library.
the memory exported from the "main" module should always be used.
i feel this a bit strange because the module calling wasi (eg. libc.so) doesn't know about the "main" module.

Read legacy/application-abi.md and inspect wasi-libc's libc.so export behavior. Then compare the shared-library handling in lld/wasm/Driver.cpp around the cited line with the two alternatives in the issue. Done means establishing and documenting the applicable memory convention, or identifying the specific tool change required.