Turn existing ifdefs around backtrace() API into a CMake SWIFT_SUPPORTS_BACKTRACE_REPORTING flag

stdlib/CMakeLists.txt

@@ -52,6 +52,16 @@ else()
   set(SWIFT_STDLIB_ENABLE_PRESPECIALIZATION_default FALSE)
 endif()
 
+if("${SWIFT_HOST_VARIANT_SDK}" MATCHES "CYGWIN")
+  set(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING_default FALSE)
+elseif("${SWIFT_HOST_VARIANT_SDK}" MATCHES "HAIKU")
+  set(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING_default FALSE)
+elseif("${SWIFT_HOST_VARIANT_SDK}" MATCHES "WASI")
+  set(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING_default FALSE)
+else()
+  set(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING_default TRUE)
+endif()
+
 #
 # User-configurable options for the standard library.
 #
@@ -75,6 +85,10 @@ option(SWIFT_STDLIB_HAS_DLADDR
        "Build stdlib assuming the runtime environment runtime environment provides dladdr API."
        TRUE)
 
+option(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING
+       "Build stdlib assuming the runtime environment provides the backtrace(3) API."
+       "${SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING_default}")
+
 option(SWIFT_RUNTIME_STATIC_IMAGE_INSPECTION
        "Build stdlib assuming the runtime environment runtime environment only supports a single runtime image with Swift code."
        FALSE)

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -347,6 +347,10 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_RUNTIME_OS_VERSIONING")
   endif()
 
+  if(SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING)
+    list(APPEND result "-DSWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING")
+  endif()
+
   set("${CFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
 endfunction()
 

stdlib/public/runtime/Errors.cpp

@@ -14,12 +14,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if defined(__CYGWIN__) || defined(__HAIKU__) || defined(__wasi__)
-#define SWIFT_SUPPORTS_BACKTRACE_REPORTING 0
-#else
-#define SWIFT_SUPPORTS_BACKTRACE_REPORTING 1
-#endif
-
 #if defined(_WIN32)
 #include <mutex>
 #endif
@@ -73,7 +67,7 @@ enum: uint32_t {
 
 using namespace swift;
 
-#if SWIFT_SUPPORTS_BACKTRACE_REPORTING && SWIFT_STDLIB_HAS_DLADDR
+#if SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING && SWIFT_STDLIB_HAS_DLADDR
 static bool getSymbolNameAddr(llvm::StringRef libraryName,
                               const SymbolInfo &syminfo,
                               std::string &symbolName, uintptr_t &addrOut) {
@@ -136,7 +130,7 @@ static bool getSymbolNameAddr(llvm::StringRef libraryName,
 
 void swift::dumpStackTraceEntry(unsigned index, void *framePC,
                                 bool shortOutput) {
-#if SWIFT_SUPPORTS_BACKTRACE_REPORTING && SWIFT_STDLIB_HAS_DLADDR
+#if SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING && SWIFT_STDLIB_HAS_DLADDR
   SymbolInfo syminfo;
 
   // 0 is failure for lookupSymbol
@@ -224,7 +218,7 @@ static _Unwind_Reason_Code SwiftUnwindFrame(struct _Unwind_Context *context, voi
 
 SWIFT_ALWAYS_INLINE
 static bool withCurrentBacktraceImpl(std::function<void(void **, int)> call) {
-#if SWIFT_SUPPORTS_BACKTRACE_REPORTING
+#if SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING
   constexpr unsigned maxSupportedStackDepth = 128;
   void *addrs[maxSupportedStackDepth];
 #if defined(_WIN32)
@@ -325,7 +319,7 @@ reportNow(uint32_t flags, const char *message)
 #elif defined(__ANDROID__)
   __android_log_print(ANDROID_LOG_FATAL, "SwiftRuntime", "%s", message);
 #endif
-#if SWIFT_SUPPORTS_BACKTRACE_REPORTING
+#if SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING
   if (flags & FatalErrorFlags::ReportBacktrace) {
     fputs("Current stack trace:\n", stderr);
     printCurrentBacktrace();

utils/build-presets.ini

@@ -2464,6 +2464,7 @@ swift-objc-interop=0
 swift-enable-compatibility-overrides=0
 swift-enable-reflection=0
 swift-stdlib-has-dladdr=0
+swift-stdlib-supports-backtrace-reporting=0
 swift-stdlib-has-darwin-libmalloc=0
 swift-stdlib-has-stdin=0
 swift-runtime-static-image-inspection=1

utils/build-script-impl

@@ -207,6 +207,7 @@ KNOWN_SETTINGS=(
     swift-enable-compatibility-overrides          "1"               "whether to support back-deploying compatibility fixes for newer apps running on older runtimes"
     swift-enable-reflection                       "1"               "whether to support reflection and mirrors"
     swift-stdlib-has-dladdr                       "1"               "whether to build stdlib assuming the runtime environment provides dladdr API"
+    swift-stdlib-supports-backtrace-reporting     ""                "whether to build stdlib assuming the runtime environment provides the backtrace(3) API, if not set defaults to true on all platforms except for Cygwin, Haiku and wasm"
     swift-runtime-static-image-inspection         "0"               "whether to build stdlib assuming the runtime environment only supports a single runtime image with Swift code"
     swift-stdlib-single-threaded-runtime          "0"               "whether to build stdlib as a single-threaded runtime only"
     swift-stdlib-os-versioning                    "1"               "whether to build stdlib with availability based on OS versions (Darwin only)"
@@ -2103,6 +2104,13 @@ for host in "${ALL_HOSTS[@]}"; do
                     )
                 fi
 
+                if [[ "${SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING}" ]] ; then
+                    cmake_options=(
+                        "${cmake_options[@]}"
+                        -DSWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING:BOOL=$(true_false "${SWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING}")
+                    )
+                fi
+
                 if [ "${SWIFT_INSTALL_COMPONENTS}" ] ; then
                     cmake_options=(
                         "${cmake_options[@]}"

utils/check_freestanding_dependencies.py

@@ -50,7 +50,7 @@
 ]
 common_expected_dependencies = [
     "___bzero", "___divti3", "___error", "___stderrp", "___stdoutp",
-    "___truncsfhf2", "___udivti3", "_abort", "_arc4random_buf", "_backtrace",
+    "___truncsfhf2", "___udivti3", "_abort", "_arc4random_buf",
     "_calloc", "_close", "_environ", "_flockfile", "_floorl", "_fprintf",
     "_fputc", "_fputs", "_free", "_funlockfile", "_fwrite", "_malloc",
     "_malloc_size", "_memchr", "_memcmp", "_memcpy", "_memmove", "_memset",