Use linker tools on OSX & Linux to limit exports (#4651)

Makefile

@@ -921,6 +921,12 @@ else
 LIBHALIDE_SONAME_FLAGS=
 endif
 
+ifeq ($(UNAME), Linux)
+LIBHALIDE_EXPORTS=-Wl,--version-script=$(ROOT_DIR)/src/exported_symbols.linux
+else
+LIBHALIDE_EXPORTS=-Wl,-exported_symbols_list $(ROOT_DIR)/src/exported_symbols.osx
+endif
+
 $(BIN_DIR)/libHalide.$(SHARED_EXT): $(OBJECTS) $(INITIAL_MODULES)
 	@mkdir -p $(@D)
 	$(CXX) -shared $(OBJECTS) $(INITIAL_MODULES) $(LLVM_LIBS_FOR_SHARED_LIBHALIDE) $(LLVM_SYSTEM_LIBS) $(COMMON_LD_FLAGS) $(INSTALL_NAME_TOOL_LD_FLAGS) $(LIBHALIDE_SONAME_FLAGS) -o $(BIN_DIR)/libHalide.$(SHARED_EXT)

src/CMakeLists.txt

@@ -370,6 +370,18 @@ add_library(Halide
             $<TARGET_OBJECTS:Halide_initmod>)
 add_library(Halide::Halide ALIAS Halide)
 
+# TODO: there is probably a more elegant way to do these conditionals in CMake
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    # using Clang
+    target_link_options(Halide PRIVATE -Wl,-exported_symbols_list ${CMAKE_CURRENT_LIST_DIR}/exported_symbols.osx)
+elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    # using GCC
+    target_link_options(Halide PRIVATE -Wl,--version-script=${CMAKE_CURRENT_LIST_DIR}/exported_symbols.linux)
+else ()
+    # TODO: implement something similar for MSVC
+    # https://github.com/halide/Halide/issues/4651
+endif ()
+
 target_link_libraries(Halide PRIVATE Halide::LLVM)
 target_link_libraries(Halide PUBLIC Halide::LanguageOptions)
 target_compile_definitions(Halide

src/exported_symbols.linux

@@ -0,0 +1,19 @@
+{
+    global:
+        # Everything at global namespace beginning with halide_
+        halide_* ;
+
+        # Some C++ classes that are overloaded at global namespace
+        # TODO: should not be necessary
+        # _ZN28halide_handle_cplusplus_type* ;
+
+        # Everything in Halide:: namespace (including nested namespace)
+        # (Don't use _Z*6Halide as that can match things like std::sort()
+        # with Halide types in the specialization)
+        _Z?6Halide* ;
+        _Z??6Halide* ;
+        _Z???6Halide* ;
+
+    local: *;
+};
+

src/exported_symbols.osx

@@ -0,0 +1,11 @@
+# Everything at global namespace beginning with halide_
+halide_*
+
+# Some C++ classes that are overloaded at global namespace
+# TODO: should not be necessary
+# __ZN28halide_handle_cplusplus_type*
+
+# Everything in Halide:: namespace (including nested namespace)
+__Z?6Halide*
+__Z??6Halide*
+__Z???6Halide*