Allow passing of wasm file into EXPORTED_FUNCTIONS

[Mintyboi]

I have a transitive dependency in my project.

• Main module
  -- sidey1
  --- sidey2

And Sidey1 is dependent on Sidey2.
To make sure that all the functions are exported correctly in Sidey2, we can use wasm-objdump -x --section=import to get the list of imports and parse it with regex to eventually populate csv file to pass into EXPORTED_FUNCTIONS.

Would it be easier if we are able to pass in a wasm module in while building the side module? eg.

emcc side2.cpp -sSIDE_MODULE=2 -o Sidey2.wasm -sEXPORTED_FUNCTIONS=@Sidey1.wasm

[sbc100]

Interesting idea! So in this case you know that the only consumer of Sidey2.wasm is Sidey1.wasm so any function not needed by Sidey1.wasm can be DCE'd.

What happens if Sidey1.wasm also contains symbols from other module, e.g. libc/main module? i.e. what happens if Sidey1.wasm imports printf? Would that not result in "undefined symbol: printf" when linking Sidey2?