[libcxx] Make libc++.so a linker script by default on most platforms.
Summary:
This patch turns on `LIBCXX_ENABLE_ABI_LINKER_SCRIPT` by default whenever `LLVM_HAVE_LINK_VERSION_SCRIPT` is ON. This turns out to be whenever:
1. WIN32 is not defined.
2 UNIX is defined.
3. APPLE is not defined.
While `LLVM_HAVE_LINK_VERSION_SCRIPT` is meant to reflect exactly what we are asking I think it's close enough.
After committing this patch Linux users will no longer have to use "-lc++abi" explicitly!
Reviewers: mclow.lists, danalbert, compnerd, jroelofs
Subscribers: emaste, rengolin, cbergstrom, cfe-commits
Differential Revision: http://reviews.llvm.org/D13739
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@250469 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7017ce4..11958d9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,12 +67,22 @@
set(CXXABIS none libcxxabi libcxxrt libstdc++ libsupc++)
set_property(CACHE LIBCXX_CXX_ABI PROPERTY STRINGS ;${CXXABIS})
+# Use a static copy of the ABI library when linking libc++. This option
+# cannot be used with LIBCXX_ENABLE_ABI_LINKER_SCRIPT.
option(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "Statically link the ABI library" OFF)
# Generate and install a linker script inplace of libc++.so. The linker script
-# will link libc++ to the correct ABI library.
+# will link libc++ to the correct ABI library. This option is on by default
+# On UNIX platforms other than Apple unless 'LIBCXX_ENABLE_STATIC_ABI_LIBRARY'
+# is on.
+set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE OFF)
+if (LLVM_HAVE_LINK_VERSION_SCRIPT AND NOT LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
+ set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE ON)
+endif()
+
option(LIBCXX_ENABLE_ABI_LINKER_SCRIPT
- "Use and install a linker script for the given ABI library" OFF)
+ "Use and install a linker script for the given ABI library"
+ ${ENABLE_LINKER_SCRIPT_DEFAULT_VALUE})
# Build libc++abi with libunwind. We need this option to determine whether to
# link with libunwind or libgcc_s while running the test cases.
diff --git a/cmake/Modules/HandleOutOfTreeLLVM.cmake b/cmake/Modules/HandleOutOfTreeLLVM.cmake
index 0e12c88..6215be7 100644
--- a/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -109,6 +109,30 @@
message(STATUS "Sphinx disabled.")
endif()
+ # FIXME - This is cribbed from HandleLLVMOptions.cmake.
+ if(WIN32)
+ set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
+ if(CYGWIN)
+ set(LLVM_ON_WIN32 0)
+ set(LLVM_ON_UNIX 1)
+ else(CYGWIN)
+ set(LLVM_ON_WIN32 1)
+ set(LLVM_ON_UNIX 0)
+ endif(CYGWIN)
+ else(WIN32)
+ if(UNIX)
+ set(LLVM_ON_WIN32 0)
+ set(LLVM_ON_UNIX 1)
+ if(APPLE)
+ set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
+ else(APPLE)
+ set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
+ endif(APPLE)
+ else(UNIX)
+ MESSAGE(SEND_ERROR "Unable to determine platform")
+ endif(UNIX)
+ endif(WIN32)
+
# Add LLVM Functions --------------------------------------------------------
include(AddLLVM OPTIONAL)
endif()
diff --git a/docs/BuildingLibcxx.rst b/docs/BuildingLibcxx.rst
index 6e45578..a7366c5 100644
--- a/docs/BuildingLibcxx.rst
+++ b/docs/BuildingLibcxx.rst
@@ -170,6 +170,14 @@
If this option is enabled, libc++ will try and link the selected ABI library
statically.
+.. option:: LIBCXX_ENABLE_ABI_LINKER_SCRIPT:BOOL
+
+ **Default**: ``ON`` by default on UNIX platforms other than Apple unless
+ 'LIBCXX_ENABLE_STATIC_ABI_LIBRARY' is ON. Otherwise the default value is ``OFF``.
+
+ This option generate and installs a linker script as ``libc++.so`` which
+ links the correct ABI library.
+
.. option:: LIBCXXABI_USE_LLVM_UNWINDER:BOOL
**Default**: ``OFF``
diff --git a/docs/UsingLibcxx.rst b/docs/UsingLibcxx.rst
index 8de58d8..2a11791 100644
--- a/docs/UsingLibcxx.rst
+++ b/docs/UsingLibcxx.rst
@@ -54,10 +54,10 @@
Using libc++ on Linux
=====================
-On Linux libc++ typically links to a shared version of libc++abi. Unfortunately
-you can't simply run clang with "-stdlib=libc++" as clang is not set up to
-link for this configuration. To get around this you'll have to manually
-link libc++abi yourself. For example:
+On Linux libc++ can typically be used with only '-stdlib=libc++'. However
+some libc++ installations require the user manually link libc++abi themselves.
+If you are running into linker errors when using libc++ try adding '-lc++abi'
+to the link line. For example:
.. code-block:: bash
