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3 Libc++ ABI stability
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6 Libc++ aims to preserve stable ABI to avoid subtle bugs when code built to the old ABI
7 is linked with the code build to the new ABI. At the same time, libc++ allows ABI-breaking
8 improvements and bugfixes for the scenarios when ABI change is not a issue.
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10 To support both cases, libc++ allows specifying the ABI version at the
11 build time. The version is defined with a cmake option
12 LIBCXX_ABI_VERSION. Another option LIBCXX_ABI_UNSTABLE can be used to
13 include all present ABI breaking features. These options translate
14 into C++ macro definitions _LIBCPP_ABI_VERSION, _LIBCPP_ABI_UNSTABLE.
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16 Any ABI-changing feature is placed under it's own macro, _LIBCPP_ABI_XXX, which is enabled
17 based on the value of _LIBCPP_ABI_VERSION. _LIBCPP_ABI_UNSTABLE, if set, enables all features at once.
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