ignoring -fPIC flag when not building with SIDE_MODULE or MAIN_MODULE

[courteous]

I have preparered a minimal CMAKE project containing 2 *.cpp files in order to show the problem

https://github.com/courteous/wasmSideModule

After a bran new installation of emscripten on ubuntu server 18.04.3 i have noticed the following problem

after i run:

cd  build
emconfigure cmake ../ -DCMAKE_BUILD_TYPE=WASM
emmake make

i get the following warrning/error:

shared:INFO: (Emscripten: Running sanity checks)
shared:WARNING: ignoring -fPIC flag when not building with SIDE_MODULE or MAIN_MODULE
shared:ERROR: treating warnings as errors (-Werror)

If i disable the line in the main CMakeLists.txt which is responsible for the -fPIC option, then the projects compiles successfully.

set(CMAKE_POSITION_INDEPENDENT_CODE ON)

However I would like to understand why setting the "MAIN_MODULE=1" in the set_target_properties CMAKE does not disable this warning/error

i.e. from the main CMakeLists.txt

set_target_properties(wasmExec PROPERTIES LINK_FLAGS "-std=c++17 -s MAIN_MODULE=1 -s WASM=1 -s TOTAL_MEMORY=512MB -s ALLOW_MEMORY_GROWTH=0 -s NO_EXIT_RUNTIME=1 -s VERBOSE=1 -s DEMANGLE_SUPPORT=1 -s DISABLE_EXCEPTION_CATCHING=0 -s ERROR_ON_UNDEFINED_SYMBOLS=0 -s EXTRA_EXPORTED_RUNTIME_METHODS='['cwrap', 'getValue', 'setValue']' " )

this is related to #10209

[sbc100]

You need to pass -s MAIN_MODULE=1 as compile flag as well as a link flag.

I'm about to remove that warning though.. at which point fPIC will be allowed again as an alternative to MAIN_MODULE=1 in the compile flags.

[sbc100]

The warning was removed in #10312

[courteous]

Sam, indeed adding a compiler flag does solve the problem, many thanks for your help