SONAME introduce option CLANG_FORCE_MATCHING_LIBCLANG_SOVERSION

This reverts commit bc39d7b.

rename CLANG_SONAME to LIBCLANG_SOVERSION

[clang][cmake] introduce option CLANG_FORCE_MATCHING_LIBCLANG_SOVERSION

Differential Revision: https://reviews.llvm.org/D132486

Author: h-vetinari

clang/CMakeLists.txt

@@ -463,6 +463,12 @@ if(CLANG_ENABLE_ARCMT)
   set(CLANG_ENABLE_OBJC_REWRITER ON)
 endif()
 
+# This option is a stop-gap, we should commit to removing this as
+# soon as possible. See discussion:
+# https://discourse.llvm.org/t/rationale-for-removing-versioned-libclang-middle-ground-to-keep-it-behind-option/
+option(CLANG_FORCE_MATCHING_LIBCLANG_SOVERSION
+  "Force the SOVERSION of libclang to be equal to CLANG_MAJOR" ON)
+
 # Clang version information
 set(CLANG_EXECUTABLE_VERSION
     "${CLANG_VERSION_MAJOR}" CACHE STRING

clang/docs/ReleaseNotes.rst

@@ -235,6 +235,8 @@ clang-extdef-mapping
 libclang
 --------
 
+- ...
+
 Static Analyzer
 ---------------
 

clang/tools/libclang/CMakeLists.txt

@@ -1,3 +1,21 @@
+# 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
+
+if(NOT CLANG_FORCE_MATCHING_LIBCLANG_SOVERSION)
+  # default is to use the SOVERSION according to ABI...
+  set(LIBCLANG_SOVERSION 13)
+else()
+  # ... unless explicily overridden
+  set(LIBCLANG_SOVERSION ${CLANG_VERSION_MAJOR})
+endif()
+
+# TODO: harmonize usage of LIBCLANG_SOVERSION / LIBCLANG_LIBARY_VERSION
+#       below; this was added under time-pressure to avoid reverting the
+#       better default from LLVM 14 for LLVM 15.0.0-rc3, hence no time
+#       to clean up previous inconsistencies.
+
 set(SOURCES
   ARCMigrate.cpp
   BuildSystem.cpp
@@ -64,7 +82,8 @@ 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_SOURCE_DIR}/libclang.exports)
+set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_CURRENT_BINARY_DIR}/libclang-generic.exports)
+set(LIBCLANG_VERSION_SCRIPT_FILE ${CMAKE_CURRENT_SOURCE_DIR}/libclang.map)
 
 if(MSVC)
   # Avoid LNK4197 by not specifying libclang.exports here.
@@ -73,6 +92,20 @@ 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 ${LIBCLANG_VERSION_SCRIPT_FILE})
+endif()
+
 if(LLVM_ENABLE_PIC OR (WIN32 AND NOT LIBCLANG_BUILD_STATIC))
   set(ENABLE_SHARED SHARED)
 endif()
@@ -145,6 +178,21 @@ if(ENABLE_SHARED)
         )
     endif()
   endif()
+  if (USE_VERSION_SCRIPT)
+    target_link_options(libclang PRIVATE "-Wl,--version-script,${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 ${LIBCLANG_SOVERSION})
+  endif()
 endif()
 
 if(INTERNAL_INSTALL_PREFIX)