Targeted reorder fix

Author: tadeja

ci/scripts/python_build_emscripten.sh

@@ -40,12 +40,4 @@ unset LDFLAGS CFLAGS CXXFLAGS CPPFLAGS
 
 pushd "${python_build_dir}"
 pyodide build
-# Verify PyInit_lib export has been kept
-python -c "
-import glob, zipfile
-whl = glob.glob('dist/pyarrow-*.whl')[0]
-z = zipfile.ZipFile(whl)
-so = [n for n in z.namelist() if n.endswith('lib.cpython-312-wasm32-emscripten.so')][0]
-print(so, 'contains PyInit_lib:', b'PyInit_lib' in z.read(so))
-"
 popd

cpp/cmake_modules/SetupCxxFlags.cmake

@@ -733,8 +733,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
   # 1) Tell it to use JavaScript / WebAssembly 64 bit number support.
   # 2) Tell it to build with support for C++ exceptions
   # 3) Skip linker flags error which happens with -soname parameter
-  set(ARROW_EMSCRIPTEN_LINKER_FLAGS
-      "-sWASM_BIGINT=1 -fexceptions -Wno-error=linkflags --profiling-funcs")
+  set(ARROW_EMSCRIPTEN_LINKER_FLAGS "-sWASM_BIGINT=1 -fexceptions -Wno-error=linkflags")
   set(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS
       "-sSIDE_MODULE=1 ${ARROW_EMSCRIPTEN_LINKER_FLAGS}")
   set(CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS

cpp/src/arrow/CMakeLists.txt

@@ -1106,8 +1106,9 @@ else()
 endif()
 
 if(ARROW_BUILD_BUNDLED_DEPENDENCIES)
-  if(CMAKE_CROSSCOMPILING)
-    # Undo PREPEND-reversed order to not break Pyodide side-module loading (GH-50774)
+  if(CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
+    # Restore the archive order (pre-GH-50650). Otherwise, wasm-ld may select
+    # duplicate vague-linkage symbols from a different member (GH-50774).
     list(REVERSE ARROW_BUNDLED_STATIC_LIBS)
   endif()
   arrow_car(_FIRST_LIB ${ARROW_BUNDLED_STATIC_LIBS})