Add a SWIFT_STDLIB_HAS_DARWIN_ASL config flag to allow removing asl_log() usage in freestanding build (#39584)

Author: kubamracek

stdlib/CMakeLists.txt

@@ -62,6 +62,12 @@ else()
   set(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING_default TRUE)
 endif()
 
+if("${SWIFT_HOST_VARIANT_SDK}" IN_LIST SWIFT_DARWIN_PLATFORMS)
+  set(SWIFT_STDLIB_HAS_ASL_default TRUE)
+else()
+  set(SWIFT_STDLIB_HAS_ASL_default FALSE)
+endif()
+
 #
 # User-configurable options for the standard library.
 #
@@ -97,6 +103,10 @@ option(SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
        "Build stdlib assuming the Darwin build of stdlib can use extended libmalloc APIs"
        TRUE)
 
+option(SWIFT_STDLIB_HAS_ASL
+       "Build stdlib assuming we can use the asl_log API."
+       "${SWIFT_STDLIB_HAS_ASL_default}")
+
 option(SWIFT_STDLIB_HAS_STDIN
        "Build stdlib assuming the platform supports stdin and getline API."
        TRUE)

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -335,6 +335,10 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC=0")
   endif()
 
+  if(SWIFT_STDLIB_HAS_ASL)
+    list(APPEND result "-DSWIFT_STDLIB_HAS_ASL")
+  endif()
+
   if(SWIFT_STDLIB_HAS_STDIN)
     list(APPEND result "-DSWIFT_STDLIB_HAS_STDIN")
   endif()

stdlib/public/LLVMSupport/ErrorHandling.cpp

@@ -41,7 +41,7 @@ void error(const char *fmt, ...) {
   vsnprintf(buffer, sizeof(buffer), fmt, argp);
   va_end(argp);
 
-#if defined(__APPLE__)
+#if SWIFT_STDLIB_HAS_ASL
   asl_log(nullptr, nullptr, ASL_LEVEL_ERR, "%s", buffer);
 #elif defined(__ANDROID__)
   __android_log_print(ANDROID_LOG_FATAL, "SwiftRuntime", "%s", buffer);

stdlib/public/runtime/Errors.cpp

@@ -314,7 +314,7 @@ reportNow(uint32_t flags, const char *message)
 #else
   write(STDERR_FILENO, message, strlen(message));
 #endif
-#if defined(__APPLE__)
+#if SWIFT_STDLIB_HAS_ASL
   asl_log(nullptr, nullptr, ASL_LEVEL_ERR, "%s", message);
 #elif defined(__ANDROID__)
   __android_log_print(ANDROID_LOG_FATAL, "SwiftRuntime", "%s", message);

utils/build-presets.ini

@@ -2466,6 +2466,7 @@ swift-enable-reflection=0
 swift-stdlib-has-dladdr=0
 swift-stdlib-supports-backtrace-reporting=0
 swift-stdlib-has-darwin-libmalloc=0
+swift-stdlib-has-asl=0
 swift-stdlib-has-stdin=0
 swift-runtime-static-image-inspection=1
 swift-stdlib-single-threaded-runtime=1

utils/build-script-impl

@@ -213,6 +213,7 @@ KNOWN_SETTINGS=(
     swift-stdlib-os-versioning                    "1"               "whether to build stdlib with availability based on OS versions (Darwin only)"
     swift-stdlib-stable-abi                       ""                "should stdlib be built with stable ABI, if not set defaults to true on Darwin, false otherwise"
     swift-stdlib-has-darwin-libmalloc             "1"               "whether the Darwin build of stdlib can use extended libmalloc APIs"
+    swift-stdlib-has-asl                          ""                "whether the stdlib can use the asl_log API, defaults to true on Darwin, false otherwise"
     swift-stdlib-has-stdin                        "1"               "whether to build stdlib assuming the platform supports stdin and getline API"
     swift-stdlib-lto                              ""                "enable LLVM LTO on the stdlib, valid values are empty string (no LTO), 'full' and 'thin'"
     swift-disable-dead-stripping                  "0"               "turns off Darwin-specific dead stripping for Swift host tools"
@@ -2111,6 +2112,13 @@ for host in "${ALL_HOSTS[@]}"; do
                     )
                 fi
 
+                if [[ "${SWIFT_STDLIB_HAS_ASL}" ]] ; then
+                    cmake_options=(
+                        "${cmake_options[@]}"
+                        -DSWIFT_STDLIB_HAS_ASL:BOOL=$(true_false "${SWIFT_STDLIB_HAS_ASL}")
+                    )
+                fi
+
                 if [ "${SWIFT_INSTALL_COMPONENTS}" ] ; then
                     cmake_options=(
                         "${cmake_options[@]}"

utils/check_freestanding_dependencies.py

@@ -60,7 +60,7 @@
 ] + icu_dependencies + cxx_dependencies + math_dependencies
 vendor_apple_specific_dependencies = [
     "__NSGetArgc", "__NSGetArgv", "___stack_chk_fail", "___stack_chk_guard",
-    "_asl_log", "_getsectiondata", "__dyld_register_func_for_add_image",
+    "_getsectiondata", "__dyld_register_func_for_add_image",
 ]
 ################################################################################