Cleanup CMake configuration for external blocks runtime support (#355)

* remove unused CMake directory

* Add FindBlocksRuntime.cmake from the libdispatch project

This is a slightly modified version of the file found in swift-corelibs-libdispatch. Notabily, the non-existent HINTS are removed.

* CMakeLists.txt: Use FindBlocksRuntime

Use cmake/FindBlocksRuntime.cmake to locate the external blocks runtime,
and do not compile the internal one.

* Only call init_trampolines when using the internal blocks rt

* Conditionally include BlockImpTest.m

* External symbols should be imported from the DLL

Author: hmelder

CMake/CMakeLists.txt

@@ -26,6 +26,9 @@ if (MINGW)
 	set(CMAKE_OBJCXX_IMPLICIT_INCLUDE_DIRECTORIES ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES})
 endif ()
 
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+list(APPEND CMAKE_PREFIX_PATH ${CMAKE_INSTALL_PREFIX})
+
 INCLUDE (CheckCXXSourceCompiles)
 INCLUDE (FetchContent)
 INCLUDE (CheckSymbolExists)
@@ -50,7 +53,6 @@ add_compile_definitions(GNUSTEP __OBJC_RUNTIME_INTERNAL__=1 __OBJC_BOOL)
 set(CMAKE_CXX_STANDARD 17)
 
 set(libobjc_ASM_SRCS 
-	block_trampolines.S
 	objc_msgSend.S)
 set(libobjc_OBJCXX_SRCS 
 	arc.mm
@@ -62,7 +64,6 @@ set(libobjc_OBJC_SRCS
 	properties.m)
 set(libobjc_C_SRCS 
 	alias_table.c
-	block_to_imp.c
 	builtin_classes.c
 	caps.c
 	category_loader.c
@@ -105,6 +106,7 @@ set(libobjc_HDRS
 set(libobjc_CXX_SRCS
 	selector_table.cc
 	)
+
 # Windows does not use DWARF EH, except when using the GNU ABI (MinGW)
 if (WIN32 AND NOT MINGW)
 	list(APPEND libobjc_CXX_SRCS eh_win32_msvc.cc)
@@ -154,6 +156,11 @@ add_compile_definitions($<$<BOOL:${STRICT_APPLE_COMPATIBILITY}>:STRICT_APPLE_COM
 configure_file(objc/objc-config.h.in objc/objc-config.h @ONLY)
 include_directories("${PROJECT_BINARY_DIR}/objc/")
 
+if (EMBEDDED_BLOCKS_RUNTIME)
+	list(APPEND libobjc_ASM_SRCS block_trampolines.S)
+	list(APPEND libobjc_C_SRCS block_to_imp.c)
+endif()
+
 if (OLDABI_COMPAT)
 	list(APPEND libobjc_C_SRCS legacy.c abi_version.c statics_loader.c)
 	add_definitions(-DOLDABI_COMPAT=1)
@@ -242,18 +249,9 @@ if (EMBEDDED_BLOCKS_RUNTIME)
 	list(APPEND libobjc_HDRS objc/blocks_runtime.h)
 	add_definitions(-DEMBEDDED_BLOCKS_RUNTIME)
 else ()
-	find_library(BLOCKS_RUNTIME_LIBRARY BlocksRuntime)
-	if (BLOCKS_RUNTIME_LIBRARY)
-		set(CMAKE_REQUIRED_LIBRARIES ${BLOCKS_RUNTIME_LIBRARY})
-		check_symbol_exists(_Block_use_RR2 "Block_private.h" HAVE_BLOCK_USE_RR2)
-		if (HAVE_BLOCK_USE_RR2)
-			add_definitions(-DHAVE_BLOCK_USE_RR2)
-		else ()
-			message(FATAL_ERROR "_Block_use_RR2() could not be found in libBlocksRuntime. Did you install libdispatch with INSTALL_PRIVATE_HEADERS=ON? Alternatively, enable EMBEDDED_BLOCKS_RUNTIME to use the built-in blocks runtime.")
-		endif ()
-		unset(CMAKE_REQUIRED_LIBRARIES)
-	else ()
-		message(FATAL_ERROR "libBlocksRuntime not found. Enable EMBEDDED_BLOCKS_RUNTIME to use the built-in blocks runtime.")
+	find_package(BlocksRuntime)
+	if (NOT BlocksRuntime_FOUND)
+		message(FATAL_ERROR "An external blocks runtime is required when not using the embedded one.")
 	endif ()
 endif ()
 
@@ -270,6 +268,22 @@ if (WIN32 AND NOT MINGW)
 	target_link_libraries(objc PUBLIC ntdll.dll)
 endif()
 
+if (NOT EMBEDDED_BLOCKS_RUNTIME)
+	# Check if the blocks runtime exports _Block_use_RR2 
+	set(CMAKE_REQUIRED_LIBRARIES ${BlocksRuntime_LIBRARIES})
+	set(CMAKE_REQUIRED_INCLUDES ${BlocksRuntime_INCLUDE_DIR})
+	check_symbol_exists(_Block_use_RR2 "Block_private.h" HAVE_BLOCK_USE_RR2)
+	unset(CMAKE_REQUIRED_LIBRARIES)
+	unset(CMAKE_REQUIRED_INCLUDES)
+
+	if (NOT HAVE_BLOCK_USE_RR2)
+		message(FATAL_ERROR "The external blocks runtime is not supported. It does not export _Block_use_RR2().")
+	endif()
+
+	target_compile_definitions(objc PRIVATE HAVE_BLOCK_USE_RR2)
+	target_link_libraries(objc PUBLIC BlocksRuntime::BlocksRuntime)
+endif()
+
 target_link_libraries(objc PRIVATE tsl::robin_map)
 
 set_target_properties(objc PROPERTIES
@@ -295,10 +309,6 @@ if (M_LIBRARY)
 	target_link_libraries(objc PUBLIC ${M_LIBRARY})
 endif ()
 
-if (BLOCKS_RUNTIME_LIBRARY)
-	target_link_libraries(objc PUBLIC ${BLOCKS_RUNTIME_LIBRARY})
-endif ()
-
 # Make weak symbols work on OS X
 if (APPLE)
 	set(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS

CMake/typeinfo_test.cc

@@ -7,10 +7,14 @@
 #include <assert.h>
 
 #ifdef EMBEDDED_BLOCKS_RUNTIME
-#define BLOCK_STORAGE OBJC_PUBLIC
+#	define BLOCK_STORAGE OBJC_PUBLIC
 #else
-#define BLOCK_STORAGE extern
-#endif
+#	if defined(_WIN32)
+#		define BLOCK_STORAGE __attribute__((dllimport))
+#	else
+#		define BLOCK_STORAGE extern
+#	endif // defined(_WIN32)
+#endif // EMBEDDED_BLOCKS_RUNTIME
 
 BLOCK_STORAGE struct objc_class _NSConcreteGlobalBlock;
 BLOCK_STORAGE struct objc_class _NSConcreteStackBlock;
@@ -76,4 +80,4 @@ PRIVATE void init_early_blocks(void)
 	_NSConcreteMallocBlock.info = objc_class_flag_is_block;
 	_NSConcreteAutoBlock.info = objc_class_flag_is_block;
 	_NSConcreteFinalizingBlock.info = objc_class_flag_is_block;
-}
+}

CMakeLists.txt

@@ -16,7 +16,6 @@ set(TESTS
 	AllocatePair.m
 	AssociatedObject.m
 	AssociatedObject2.m
-	BlockImpTest.m
 	BlockTest_arc.m
 	ConstantString.m
 	Category.m
@@ -54,6 +53,10 @@ set(TESTS
 	UnexpectedException.m
 )
 
+if (EMBEDDED_BLOCKS_RUNTIME)
+	list(APPEND TESTS BlockImpTest.m)
+endif()
+
 set(ENABLE_ALL_OBJC_ARC_TESTS On)
 
 if (WIN32)

NSBlocks.m

@@ -0,0 +1,44 @@
+#.rst:
+# FindBlocksRuntime
+# -----------------
+#
+# Find libBlocksRuntime library and headers.
+#
+# The module defines the following variables:
+#
+# ##
+#
+# BlocksRuntime_FOUND        - true if libBlocksRuntime was found
+# BlocksRuntime_INCLUDE_DIR  - include search path
+# BlocksRuntime_LIBRARIES    - libraries to link
+
+if(BlocksRuntime_INCLUDE_DIR AND BlocksRuntime_LIBRARIES)
+  set(BlocksRuntime_FOUND TRUE)
+else()
+  find_path(BlocksRuntime_INCLUDE_DIR
+            NAMES
+              Block.h Block_private.h)
+  find_library(BlocksRuntime_LIBRARIES
+               NAMES
+                 BlocksRuntime libBlocksRuntime)
+
+  include(FindPackageHandleStandardArgs)
+  find_package_handle_standard_args(BlocksRuntime
+                                    REQUIRED_VARS
+                                      BlocksRuntime_LIBRARIES
+                                      BlocksRuntime_INCLUDE_DIR)
+
+  mark_as_advanced(BlocksRuntime_LIBRARIES BlocksRuntime_INCLUDE_DIR)
+endif()
+
+if(BlocksRuntime_FOUND)
+  if(NOT TARGET BlocksRuntime::BlocksRuntime)
+    add_library(BlocksRuntime::BlocksRuntime UNKNOWN IMPORTED)
+    set_target_properties(BlocksRuntime::BlocksRuntime
+                          PROPERTIES
+                            IMPORTED_LOCATION
+                              ${BlocksRuntime_LIBRARIES}
+                            INTERFACE_INCLUDE_DIRECTORIES
+                              ${BlocksRuntime_INCLUDE_DIR})
+  endif()
+endif()

Test/CMakeLists.txt

@@ -59,7 +59,9 @@ static void init_runtime(void)
 		init_alias_table();
 		init_early_blocks();
 		init_arc();
+#if defined(EMBEDDED_BLOCKS_RUNTIME)
 		init_trampolines();
+#endif
 		init_builtin_classes();
 		first_run = NO;
 		if (getenv("LIBOBJC_MEMORY_PROFILE"))