fix(shared_lib): force-load archive members into shared library

Passing libluos_engine.a directly to the linker produced a dylib/so
with zero symbols: a static archive is only searched for already-
referenced undefined symbols, and the output library starts empty so
no archive members are ever pulled in.

Use -Wl,--whole-archive / -Wl,--no-whole-archive on Linux and Windows
and -Wl,-force_load on macOS so every object in libluos_engine.a is
linked into the resulting shared library.

Ref: https://stackoverflow.com/questions/77983254/

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nicolas-rabault

src/shared_lib_build.py

@@ -22,18 +22,18 @@ def shared_lib(source, target, env):
                 break
 
     if libPath is not None:
-        # Convert the luos_engine.a archive to a shared library
+        # Convert the luos_engine.a archive to a shared library.
+        # A static archive is only searched for already-referenced symbols, so
+        # linking it into an otherwise empty shared lib yields zero symbols.
+        # Force the linker to include every object from the archive.
         if (pf.system() == 'Windows'):
-            env.Execute("gcc -shared -fPIC  -o $BUILD_DIR/libluos_engine.dll " + libPath)
+            env.Execute("gcc -shared -fPIC -o $BUILD_DIR/libluos_engine.dll -Wl,--whole-archive " + libPath + " -Wl,--no-whole-archive")
             click.secho("* Luos engine shared library available in " + str(env.subst("$BUILD_DIR")) + "/libluos_engine.dll .", fg="green")
         elif (pf.system() == 'Linux'):
-            env.Execute("gcc -shared -fPIC -o $BUILD_DIR/libluos_engine.so " + libPath)
+            env.Execute("gcc -shared -fPIC -o $BUILD_DIR/libluos_engine.so -Wl,--whole-archive " + libPath + " -Wl,--no-whole-archive")
             click.secho("* Luos engine shared library available in " + str(env.subst("$BUILD_DIR")) + "/libluos_engine.so .", fg="green")
         elif (pf.system() == 'Darwin'):
-            #for networklib in networklibs:
-                #env.Execute("gcc -v -dynamiclib -install_name $BUILD_DIR/" + os.path.basename(networklib)[0:-10] + "_luos_engine.dylib -o $BUILD_DIR/" + os.path.basename(networklib)[0:-10] + "_luos_engine.dylib " + libPath + " " + networklib)
-
-            env.Execute("gcc -v -dynamiclib -fPIC -fvisibility=default -install_name $BUILD_DIR -o $BUILD_DIR/libluos_engine.dylib " + libPath)
+            env.Execute("gcc -dynamiclib -fPIC -fvisibility=default -install_name $BUILD_DIR -o $BUILD_DIR/libluos_engine.dylib -Wl,-force_load," + libPath)
             click.secho("\n")
             click.secho("Luos engine shared libraries available in " + str(env.subst("$BUILD_DIR")) + "/ :", underline=True)
             for networklib in networklibs: