engine-dylib with singlepass compiler fails on Mac with ld: illegal text-relocation

[tzemanovic]

Hello, I'm trying to use engine-dylib together with the singlepass compiler.

Describe the bug

The simple wasm code in https://github.com/wasmerio/wasmer/blob/master/examples/engine_dylib.rs#L27 works fine, but when I tried to use some WASM code compiled from Rust instead, I noticed that this can in some cases fail in the linker with "ld: illegal text-relocation":

Shared object file generator failed with:
stderr:Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin19.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 \"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld\" -demangle -lto_library /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/libLTO.dylib -dynamic -dylib -arch x86_64 -platform_version macos 10.15.0 10.15.6 -syslibroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -o /var/folders/8n/xzxk5c154qzg_chndqmzgfdr0000gp/T/wasmer_dylib_aOgbIS.dylib -L/usr/local/lib /var/folders/8n/xzxk5c154qzg_chndqmzgfdr0000gp/T/wasmer_dylib_07B9ou.o -undefined dynamic_lookup -lSystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/12.0.0/lib/darwin/libclang_rt.osx.a
ld: illegal text-relocation to '_wasmer_function__61' in /var/folders/8n/xzxk5c154qzg_chndqmzgfdr0000gp/T/wasmer_dylib_07B9ou.o from '_wasmer_function__0' in /var/folders/8n/xzxk5c154qzg_chndqmzgfdr0000gp/T/wasmer_dylib_07B9ou.o for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Concretely, it seems that the text-relocation is applied on code that uses function pointers.

Steps to reproduce

I've updated the example to demonstrate the issue with WASM code compiled from Rust code that uses a function pointer: heliaxdev@cb1833f

Expected behavior

The example should successfully load, compile and run the exported function (works on linux - returns Results: [I32(23)]).

[epilys]

engine-dylib was removed in #2925 for the 3.0 release.