Revert "[libc++] Don't try to be compatible with libstdc++ in __libcpp_refstring on iOS (#170816)" #173099
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…p_refstring on iOS (llvm#170816)" This reverts commit b2ddb90. Sadly, I was wrong when I said that Apple didn't ship libstdc++.dylib on iOS. We actually still do, it's just not part of the shared cache, which is why I missed it. Hence, it is still possible to encounter libstdc++.dylib in processes running on iOS.
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@llvm/pr-subscribers-libcxx Author: Louis Dionne (ldionne) ChangesThis reverts commit b2ddb90. Sadly, I was wrong when I said that Apple didn't ship libstdc++.dylib on iOS. We actually still do, it's just not part of the shared cache, which is why I missed it. Hence, it is still possible to encounter libstdc++.dylib in processes running on iOS. Full diff: https://github.com/llvm/llvm-project/pull/173099.diff 1 Files Affected:
diff --git a/libcxx/src/include/refstring.h b/libcxx/src/include/refstring.h
index 1c73c60f9ced1..3e0ec7a97c7be 100644
--- a/libcxx/src/include/refstring.h
+++ b/libcxx/src/include/refstring.h
@@ -15,7 +15,7 @@
#include <cstring>
#include <stdexcept>
-// MacOS used to ship with libstdc++, and still support old applications
+// MacOS and iOS used to ship with libstdc++, and still support old applications
// linking against libstdc++. The libc++ and libstdc++ exceptions are supposed
// to be ABI compatible, such that they can be thrown from one library and caught
// in the other.
@@ -25,7 +25,7 @@
// string singleton before manipulating the reference count. This is done so that
// if an exception is created with a zero-length string in libstdc++, libc++abi
// won't try to delete the memory.
-#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) || defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
# define _LIBCPP_CHECK_FOR_GCC_EMPTY_STRING_STORAGE
# include <dlfcn.h>
# include <mach-o/dyld.h>
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ldionne
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Dec 19, 2025
| // if an exception is created with a zero-length string in libstdc++, libc++abi | ||
| // won't try to delete the memory. | ||
| #if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) | ||
| #if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) || defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) |
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That being said, I am still investigating whether we can get rid of this for macOS on arm64. I think we'll be able to.
If that's the case, we'd have to support this on iOS arm64 and on macOS x86_64.
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This reverts commit b2ddb90. Sadly, I was wrong when I said that Apple didn't ship libstdc++.dylib on iOS. We actually still do, it's just not part of the shared cache, which is why I missed it.
Hence, it is still possible to encounter libstdc++.dylib in processes running on iOS.