Fix emscripten build by removing dummy atexit function - #4435
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Since emscripten-core/emscripten#15905 landed emscripten now includes its own dummy atexit function when building with EXIT_RUNTIME=0. This dummy function conflicts with the emscripten-provided one: ``` wasm-ld: error: duplicate symbol: atexit >>> defined in CMakeFiles/binaryen_wasm.dir/src/binaryen-c.cpp.o >>> defined in ...wasm32-emscripten/lto/libnoexit.a(atexit_dummy.o) ``` Normally overriding symbols from libc does not causes issues but one needs to be sure to override all the symbols in a given object file so that the object in question (atexit_dummy.o) does not get linked in. In this case some other symbol being defined in in atexit_dummy.o (e.g. __cxa_atexit) is likely the cause of the conflict. Overriding symbols from libc is likely to break in this way as the libc evolves, and since emscripten is now providing a dummy, just as we want, its better/safer to simply remove our dummy.
kripken
approved these changes
Jan 9, 2022
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Since emscripten-core/emscripten#15905 landed
emscripten now includes its own dummy atexit function when building with
EXIT_RUNTIME=0.
This dummy function conflicts with the emscripten-provided one:
Normally overriding symbols from libc does not causes issues but one
needs to be sure to override all the symbols in a given object file so
that the object in question (atexit_dummy.o) does not get linked in. In
this case some other symbol being defined in in atexit_dummy.o (e.g.
__cxa_atexit) is likely the cause of the conflict.
Overriding symbols from libc is likely to break in this way as the libc
evolves, and since emscripten is now providing a dummy, just as we want,
its better/safer to simply remove our dummy.