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Previously, we would define new/delete in both libc++ and libc++abi. Not only does this cause code bloat, but also it's technically an ODR violation since we don't know which operator will be selected. Furthermore, since those are weak definitions, we should strive to have as few of them as possible (to improve load times). My preferred choice would have been to put the operators in libc++ only by default, however that would create a circular dependency between libc++ and libc++abi, which GNU linkers don't handle. Folks who want to ship new/delete in libc++ instead of libc++abi are free to do so by turning on LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS at CMake configure time. On Apple platforms, this shouldn't be an ABI break because we re-export the new/delete symbols from libc++abi. This change actually makes libc++ behave closer to the system libc++ shipped on Apple platforms. On other platforms, this is an ABI break for people linking against libc++ but not libc++abi. However, vendors have been consulted in D68269 and no objection was raised. Furthermore, the definitions can be controlled to appear in libc++ instead with the CMake option. Differential Revision: https://reviews.llvm.org/D68269
This directory contains abi lists representing the symbols exported by the libc++ library. The lists are generated using sym_extract.py. Every time a symbol is added or removed from the libc++ library each of the lists *MUST* be updated to reflect the changes. TODO Add more documentation about generating and using the lists. TODO Add more documentation about the build configuration the lists are generated against.