bazel build seems to have having trouble with the trasition to true shared libraries.

[sbc100]

I'm seeing errors like this trying to integrate the latest emscripten changes that include emscripten-core/emscripten#25930

WARNING: For repository 'rules_cc', the root module requires module version rules_cc@0.2.16, but got rules_cc@0.2.17 in the resolved dependency graph. Please update the version in your MODULE.bazel or set --check_direct_dependencies=off
INFO: Analyzed target //long_command_line:long_command_line_wasm (3 packages loaded, 6209 targets configured).
ERROR: /root/project/bazel/test_external/long_command_line/BUILD.bazel:48:10: Linking long_command_line/liblong_command_line.so failed: (Exit 1): emcc_link.sh failed: error executing CppLink command (from cc_binary rule target //long_command_line:long_command_line) external/emsdk+/emscripten_toolchain/emcc_link.sh @bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line.so-0.params

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file01_a.a(long_command_line_file01.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file01_a.a(long_command_line_file01.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file01_a.a(long_command_line_file01.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::ctype<char>::id`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file02_a.a(long_command_line_file02.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file02_a.a(long_command_line_file02.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file03_a.a(long_command_line_file03.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file03_a.a(long_command_line_file03.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file04_a.a(long_command_line_file04.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file04_a.a(long_command_line_file04.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file05_a.a(long_command_line_file05.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file05_a.a(long_command_line_file05.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file06_a.a(long_command_line_file06.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file06_a.a(long_command_line_file06.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file07_a.a(long_command_line_file07.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file07_a.a(long_command_line_file07.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file08_a.a(long_command_line_file08.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file08_a.a(long_command_line_file08.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file09_a.a(long_command_line_file09.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file09_a.a(long_command_line_file09.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `.L.str`; recompile with -fPIC
wasm-ld: error: bazel-out/wasm-fastbuild-ST-97b75ba167b6/bin/long_command_line/liblong_command_line_file10_a.a(long_command_line_file10.o): relocation R_WASM_MEMORY_ADDR_SLEB cannot be used against symbol `std::__2::cout`; recompile with -fPIC
wasm-ld: error: too many errors emitted, stopping now (use -error-limit=0 to see all errors)

I guess what is happening here is that bazel has been historically been passing -shared but getting our fake dynamic libraries?

[sbc100]

@walkingeyerobot @DoDoENT why ideas about this?

[sbc100]

Actually it looks like the problem might just be that bazel/test_external/long_command_line/BUILD.bazel includes linkshared = True.

I wonder if that was a deliberate choice. It looks like at was added in #1373. @zaucy do you happen to remember why you added this line?

[DoDoENT]

I see it being added here as part of the PR you reference, but to me it just looks like a copy/paste from another (possibly desktop) example.

I've never seen linkshared working with emscripten.

EDIT: for cc_binary, linkshared doesn't even make sense. What does it mean to have a "shared binary"? I see in the Bazel C++ documentation that this option on cc_binary is specific to the GCC/Linux world and may even be a legacy from earlier versions of Bazel. (e.g., if you want to build a binary that can be used both as a standalone binary and as a shared library, like libc.so)

Anyway, for a modern CC Bazel project, it's recommended to avoid using this flag in cc_library or cc_binary and use dedicated cc_shared_library or cc_static_library rules to give a cc_library a "flavor" (thus, cc_library is most similar to "object library" in CMake).

[sbc100]

I remove the linkshared = True from the test in #1715.

Once emscripten 6.0.0 ships we can try to enable true shared libraries in bazel. I'll leave this bug open for that.

[zaucy]

@sbc100 I don't believe the choice was for any particular reason. It was just the test case in my project that was failing. We had a wasm cc_binary that was a shared library that triggered the long path issue on windows, but upon looking at it again I'm sure it would be fine to remove it. It has a main method afterall.

Forgive my memory as I added this a long time ago 😅