For the 'minimal' stdlib, disable Objective-C interop (swiftlang#33427)

Author: kubamracek

CMakeLists.txt

@@ -369,6 +369,10 @@ option(SWIFT_REPORT_STATISTICS
     "Create json files which contain internal compilation statistics"
     FALSE)
 
+option(SWIFT_DISABLE_OBJC_INTEROP
+    "Disable Objective-C interoperability even on platforms what would normally have it"
+    FALSE)
+
 #
 # User-configurable experimental options.  Do not use in production builds.
 #

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -329,6 +329,10 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-D_WASI_EMULATED_MMAN")
   endif()
 
+  if(SWIFT_DISABLE_OBJC_INTEROP)
+    list(APPEND result "-DSWIFT_OBJC_INTEROP=0")
+  endif()
+
   set("${CFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
 endfunction()
 

stdlib/cmake/modules/SwiftSource.cmake

@@ -450,6 +450,10 @@ function(_compile_swift_files
     list(APPEND swift_flags "-warn-swift3-objc-inference-complete")
   endif()
 
+  if(SWIFT_DISABLE_OBJC_INTEROP)
+    list(APPEND swift_flags "-Xfrontend" "-disable-objc-interop")
+  endif()
+
   list(APPEND swift_flags ${SWIFT_EXPERIMENTAL_EXTRA_FLAGS})
 
   if(SWIFTFILE_OPT_FLAGS)

stdlib/public/runtime/ImageInspectionMachO.cpp

@@ -21,6 +21,7 @@
 #if defined(__APPLE__) && defined(__MACH__)
 
 #include "ImageInspection.h"
+#include "swift/Runtime/Config.h"
 #include <mach-o/dyld.h>
 #include <mach-o/getsect.h>
 #include <objc/runtime.h>
@@ -121,7 +122,7 @@ void addImageCallback2Sections(const mach_header *mh, intptr_t vmaddr_slide) {
 
 } // end anonymous namespace
 
-#if OBJC_ADDLOADIMAGEFUNC_DEFINED
+#if OBJC_ADDLOADIMAGEFUNC_DEFINED && SWIFT_OBJC_INTEROP
 #define REGISTER_FUNC(...)                                               \
   if (__builtin_available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)) { \
     objc_addLoadImageFunc(__VA_ARGS__);                                  \

utils/build-presets.ini

@@ -2389,6 +2389,7 @@ enable-experimental-concurrency=0
 build-swift-dynamic-sdk-overlay=0
 build-swift-dynamic-stdlib=0
 build-swift-static-stdlib=1
+swift-objc-interop=0
 
 [preset: stdlib_S_standalone_minimal_macho_x86_64,build]
 mixin-preset=

utils/build-script-impl

@@ -192,6 +192,7 @@ KNOWN_SETTINGS=(
     report-statistics                             "0"               "set to 1 to generate compilation statistics files for swift libraries"
     sil-verify-all                                "0"               "If enabled, run the SIL verifier after each transform when building Swift files during this build process"
     stdlib-deployment-targets                     ""                "space-separated list of targets to configure the Swift standard library to be compiled or cross-compiled for"
+    swift-objc-interop                            ""                "whether to enable interoperability with Objective-C, default is 1 on Apple platfors, 0 otherwise"
 
     ## FREESTANDING Stdlib Options
     swift-freestanding-sdk                      ""                "which SDK to use when building the FREESTANDING stdlib"
@@ -1816,6 +1817,13 @@ for host in "${ALL_HOSTS[@]}"; do
                     )
                 fi
 
+                if [[ "${SWIFT_OBJC_INTEROP}" == "0" ]] ; then
+                    cmake_options=(
+                        "${cmake_options[@]}"
+                        -DSWIFT_DISABLE_OBJC_INTEROP:BOOL=True
+                    )
+                fi
+
                 if [[ "${SWIFT_PRIMARY_VARIANT_SDK}" ]] ; then
                     cmake_options=(
                         "${cmake_options[@]}"