libclang.so: Make SONAME the same as LLVM version

This partially reverts c7b3a91.  Having
libclang.so with a different SONAME than the other LLVM libraries was
causing a lot of confusion for users.  Also, this change did not really
acheive it's purpose of allowing apps to use newer versions of
libclang.so without rebuilding, because a new version of libclang.so
requires a new version of libLLVM.so, which does not have a stable ABI.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D129160

Author: tstellar

clang/docs/ReleaseNotes.rst

@@ -670,7 +670,8 @@ clang-extdef-mapping
 libclang
 --------
 
-- ...
+- The soversion for libclang will now change for each new LLVM major release.  This matches
+  the behavior of clang <= 13.
 
 Static Analyzer
 ---------------

clang/tools/libclang/CMakeLists.txt

@@ -1,9 +1,3 @@
-# The SOVERSION should be updated only if a change is made to the libclang
-# ABI, and when it is updated, it should be updated to the current
-# LLVM_VERSION_MAJOR.
-# Please also see clang/tools/libclang/libclang.map
-set(CLANG_SONAME 13)
-
 set(SOURCES
   ARCMigrate.cpp
   BuildSystem.cpp
@@ -70,8 +64,7 @@ endif ()
 option(LIBCLANG_BUILD_STATIC
   "Build libclang as a static library (in addition to a shared one)" OFF)
 
-set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_CURRENT_BINARY_DIR}/libclang-generic.exports)
-set(LIBCLANG_VERSION_SCRIPT_FILE ${CMAKE_CURRENT_SOURCE_DIR}/libclang.map)
+set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_CURRENT_SOURCE_DIR}/libclang.exports)
 
 if(MSVC)
   # Avoid LNK4197 by not specifying libclang.exports here.
@@ -80,20 +73,6 @@ if(MSVC)
   set(LLVM_EXPORTED_SYMBOL_FILE)
 endif()
 
-if (UNIX AND NOT APPLE)
-  set(LLVM_EXPORTED_SYMBOL_FILE)
-  set(USE_VERSION_SCRIPT ${LLVM_HAVE_LINK_VERSION_SCRIPT})
-endif()
-
-if (LLVM_EXPORTED_SYMBOL_FILE)
-  add_custom_command(OUTPUT ${LLVM_EXPORTED_SYMBOL_FILE}
-                     COMMAND "${Python3_EXECUTABLE}"
-                       ARGS ${CMAKE_CURRENT_SOURCE_DIR}/linker-script-to-export-list.py
-                            ${LIBCLANG_VERSION_SCRIPT_FILE}
-                            ${LLVM_EXPORTED_SYMBOL_FILE}
-                     DEPENDS ${LIBCLANG_VERSION_SCRIPT_FILE})
-endif()
-
 if(LLVM_ENABLE_PIC OR (WIN32 AND NOT LIBCLANG_BUILD_STATIC))
   set(ENABLE_SHARED SHARED)
 endif()
@@ -166,21 +145,6 @@ if(ENABLE_SHARED)
         )
     endif()
   endif()
-  if (USE_VERSION_SCRIPT)
-    target_link_options(libclang PRIVATE "-Wl,--version-script,${CMAKE_CURRENT_SOURCE_DIR}/libclang.map")
-    # The Solaris 11.4 linker supports a subset of GNU ld version scripts,
-    # but requires a special option to enable it.
-    if (${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
-      target_link_options(libclang PRIVATE "-Wl,-z,gnu-version-script-compat")
-    endif()
-    # Ensure that libclang.so gets rebuilt when the linker script changes.
-    set_property(SOURCE ARCMigrate.cpp APPEND PROPERTY
-                 OBJECT_DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/libclang.map)
-
-    set_target_properties(libclang PROPERTIES
-                          VERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}${LLVM_VERSION_SUFFIX}
-                          SOVERSION ${CLANG_SONAME})
-  endif()
 endif()
 
 if(INTERNAL_INSTALL_PREFIX)