[libcxx-commits] [PATCH] D118620: [SystemZ][z/OS] Build several exception derived classes as a separate library

[Fanbo Meng via Phabricator via libcxx-commits]

fanbo-meng added inline comments.


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Comment at: libcxx/include/__config:801-804
+#  else
+#    define _LIBCPP_BEGIN_NAMESPACE_STD_EXCEPTION _LIBCPP_BEGIN_NAMESPACE_STD
+#    define _LIBCPP_END_NAMESPACE_STD_EXCEPTION _LIBCPP_END_NAMESPACE_STD
+#  endif
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ldionne wrote:
> It seems to me that we *always* want the namespace for exceptions to be `namespace std` only, without the ABI namespace.
> 
> I think it only falls down for `bad_weak_ptr`, which we seem to have defined in `std::__1` instead of `std::`. Is that correct?
That's correct, in our case we want them to have `std::` namespace only so we define `_LIBCPP_BEGIN_NAMESPACE_STD_EXCEPTION` for `bad_weak_ptr `. 
For the other three classes they are already using only `std::` namespace, that's why we kept their existing `std::` namespace in the new files to avoid inconsistency. 


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Comment at: libcxx/src/CMakeLists.txt:296
 
+if (LIBCXX_EXCEPTION_ZOS_BUILD)
+  add_library(cxx_exception SHARED ${exclude_from_all} ${LIBCXX_EXCEPTION_SOURCES} ${LIBCXX_HEADERS})
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ldionne wrote:
> I think there's something greater trying to emerge here. We already define some exception types inside libc++abi in namespace `std`. We should have a consistent approach with all those. In fact, perhaps what we want is to create either a static archive or a shared library with all those exception types, from libc++ and libc++abi. The default configuration would be to statically link that library into libc++, but other configurations could be possible, like leaving it be its own dylib (your use case).
Our initial approach was to move all exception symbols from libc++ to libc++abi, but then we discovered some exception classes have dependencies on libcxx symbols, for example `runtime_error(const string& msg)` requires access to string methods. Therefore they have to be left in libc++ so I don't think it would be possible to move everything into a unified library.


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  https://reviews.llvm.org/D118620/new/

https://reviews.llvm.org/D118620