[C++] Gandiva exposes LLVM symbols

[asfimport]

Despite the fact the cmake seems to indicate the opposite, I see that gandiva on macOS is compiled with LLVM symbols exported. E.g.:

nm ../sw/osx_x86-64/arrow/latest/lib/libgandiva.dylib | grep _LLVMEnablePrettyStackTrace
000000000120b5a0 T _LLVMEnablePrettyStackTrace

is that expected?

Reporter: Giulio Eulisse

_{Note: This issue was originally created as ARROW-7241. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm: It is not our intent to expose any symbols from statically-linked dependencies

[asfimport]

Giulio Eulisse: Update on this.

On linux it seems to be sufficient to build LLVM with:

-DCMAKE_CXX_FLAGS=-fvisibility=hidden -DCLANG_TOOL_LIBCLANG_BUILD=OFF

on macOS this is not the case. So far we managed to get the wanted result by hacking:

set_target_properties(${LIB_NAME}_shared PROPERTIES LINK_FLAGS -Wl,-unexported_symbol,_LLVMEnablePrettyStackTrace)

into cmake_modules/BuildUtils.cmake. This is of course not an acceptable solution because it hides only the symbol we check for, not all of them. Any better ideas?

[asfimport]

Giulio Eulisse: In the end we settled to:

cat >no-llvm-symbols.txt << EOF
_LLVM*
__ZN4llvm*
__ZNK4llvm*
EOF
cmake ... -DCMAKE_SHARED_LINKER_FLAGS="-Wl,-unexported_symbols_list,$PWD/no-llvm-symbols.txt"

which hides everything from LLVM which does not come from Gandiva itself. In our limited tests this works fine. Is this of common interest? How do we proceed from here?

[asfimport]

Antoine Pitrou / @pitrou: [~ktf] Sorry  for the delay. Yes, this would be of interest. I've tried this patch: https://gist.github.com/pitrou/0e88d3d829175a6179b70671ed49a865

But unfortunately it crashes at the end of one of the Gandiva tests (in the llvm::LLVMContext destructor). Do you want to take it up and investigate?

[asfimport]

Giulio Eulisse: Sorry, by now we have fixed the dependency which was more under our control, so this is not particularly needed anymore on our side and I've other priorities.