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Diffstat (limited to 'libcxx/docs')
| -rw-r--r-- | libcxx/docs/Abi.rst | 17 | ||||
| -rw-r--r-- | libcxx/docs/BuildingLibcxx.rst | 19 |
2 files changed, 36 insertions, 0 deletions
diff --git a/libcxx/docs/Abi.rst b/libcxx/docs/Abi.rst new file mode 100644 index 00000000000..5960dd18610 --- /dev/null +++ b/libcxx/docs/Abi.rst @@ -0,0 +1,17 @@ + +==================== +Libc++ ABI stability +==================== + +Libc++ aims to preserve stable ABI to avoid subtle bugs when code built to the old ABI +is linked with the code build to the new ABI. At the same time, libc++ allows ABI-breaking +improvements and bugfixes for the scenarios when ABI change is not a issue. + +To support both cases, libc++ allows specifying the ABI version at the +build time. The version is defined with a cmake option +LIBCXX_ABI_VERSION. Another option LIBCXX_ABI_UNSTABLE can be used to +include all present ABI breaking features. These options translate +into C++ macro definitions _LIBCPP_ABI_VERSION, _LIBCPP_ABI_UNSTABLE. + +Any ABI-changing feature is placed under it's own macro, _LIBCPP_ABI_XXX, which is enabled +based on the value of _LIBCPP_ABI_VERSION. _LIBCPP_ABI_UNSTABLE, if set, enables all features at once. diff --git a/libcxx/docs/BuildingLibcxx.rst b/libcxx/docs/BuildingLibcxx.rst index e343dfddbf9..6e45578dbb9 100644 --- a/libcxx/docs/BuildingLibcxx.rst +++ b/libcxx/docs/BuildingLibcxx.rst @@ -193,6 +193,25 @@ libc++ Feature options Build libc++ with run time type information. + +libc++ Feature options +---------------------- + +The following options allow building libc++ for a different ABI version. + +.. option:: LIBCXX_ABI_VERSION:STRING + + **Default**: ``1`` + + Defines the target ABI version of libc++. + +.. option:: LIBCXX_ABI_UNSTABLE:BOOL + + **Default**: ``OFF`` + + Build the "unstable" ABI version of libc++. Includes all ABI changing features + on top of the current stable version. + .. _LLVM-specific variables: LLVM-specific options |
