Demo of Linux 'strip' command damaging emscripten .a files

readme.md

With the 'strip' in the Makefile:

$ make
emcc  -c -o b.o b.c
emcc  -c -o a.o a.c
emar crs liba.a a.o
# Removing this 'strip' results in not failing
strip liba.a
strip:liba.a(a_66244f1c.o): Unable to recognise the format of file: file format not recognized
emcc  -o b.js -L. -la b.o
wasm-ld: error: ./liba.a: archive has no index; run ranlib to add one
shared:ERROR: '/home/brion/src/emsdk/upstream/bin/wasm-ld -o /tmp/emscripten_temp_HVxR_2/b.wasm --allow-undefined --lto-O0 -L. ./liba.a -L/home/brion/src/emsdk/upstream/emscripten/system/local/lib b.o -L/home/brion/src/emsdk/upstream/emscripten/system/lib -L/home/brion/.emscripten_cache/wasm-obj /home/brion/.emscripten_cache/wasm-obj/libc.a /home/brion/.emscripten_cache/wasm-obj/libcompiler_rt.a /home/brion/.emscripten_cache/wasm-obj/libc-wasm.a /home/brion/.emscripten_cache/wasm-obj/libdlmalloc.a /home/brion/.emscripten_cache/wasm-obj/libpthread_stub.a /home/brion/.emscripten_cache/wasm-obj/libc_rt_wasm.a --import-memory --import-table -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --export __wasm_call_ctors --export __data_end --export main --export malloc --export free --export setThrew --export __errno_location --export fflush -z stack-size=5242880 --initial-memory=16777216 --no-entry --max-memory=16777216 --global-base=1024' failed (1)
make: *** [Makefile:21: b.js] Error 1

Without the 'strip' in the Makefile, it builds as expected.

Tested on Ubuntu 19.04 with emscripten 1.39.0 LLVM backend (where it fails) and Fastcomp backend (where it compiles through anyway).

a.c

#include "a.h"

int func_a(void) {
    return 42;
}

a.h

extern int func_a(void);

b.c

#include <stdio.h>
#include "a.h"

int main(int argc, const char **argv) {
    printf("%d\n", func_a());
    return 0;
}

Makefile

CFLAGS=

all : b.js

clean :
	rm -f a.o b.o liba.a b.js b.wasm

a.o : a.c a.h
	emcc $(CFLAGS) -c -o a.o a.c

b.o : b.c a.h
	emcc $(CFLAGS) -c -o b.o b.c


liba.a : a.o
	emar crs liba.a a.o
	# Removing this 'strip' results in not failing
	strip liba.a

b.js : b.o liba.a
	emcc $(CFLAGS) -o b.js -L. b.o -la