While compiling libexpat to run under WebAssembly System Interface (WASI for short), I run into following error:

wasm-ld: error: libexpat.a(xmlparse.c.obj): undefined symbol: getpid

The only place where getpid is used in libexpat is this line:

entropy = gather_time_entropy() ^ getpid();

The problem is that WASI-libc defines getpid in headers, but provides no implementation for it.
While libwasi-emulated-getpid.a exists, I guess it is an unneeded dependency that provides no entropy at all.

So I believe it makes sense to remove dependency on getpid when targeting WASI