[llvm] [llvm-shlib] Change libLLVM-$MAJOR.so symlink to point to versioned SO (PR #82660)

[Tom Stellard via llvm-commits]

https://github.com/tstellar updated https://github.com/llvm/llvm-project/pull/82660

>From 112e69dfdbbc2ef2f9ae88eea1a55180907cfbf4 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Thu, 22 Feb 2024 17:25:22 +0000
Subject: [PATCH 1/3] [llvm-shlib] Change libLLVM-$MAJOR.so symlink to point to
 versioned SO

This symlink was added in 91a384621e5b762d9c173ffd247cfeadd5f436a2 to
maintain backwards compatibility, but it needs to point to
libLLVM.so.$MAJOR.$MINOR rather than libLLVM.so.  This works better for
distros that ship libLLVM.so and libLLVM.so.$MAJOR.$MINOR in separate
packages and also prevents mistakes like
libLLVM-19.so -> libLLVM.so -> libLLVM.so.18.1

Fixes #82647
---
 llvm/cmake/modules/AddLLVM.cmake     | 8 ++++++--
 llvm/tools/llvm-shlib/CMakeLists.txt | 4 ++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index 5fc663d10b8f77..abd119f46aeb80 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -2074,7 +2074,7 @@ function(add_lit_testsuites project directory)
 endfunction()
 
 function(llvm_install_library_symlink name dest type)
-  cmake_parse_arguments(ARG "" "COMPONENT" "" ${ARGN})
+  cmake_parse_arguments(ARG "COMPONENT" "SOVERSION" ${ARGN})
   foreach(path ${CMAKE_MODULE_PATH})
     if(EXISTS ${path}/LLVMInstallSymlink.cmake)
       set(INSTALL_SYMLINK ${path}/LLVMInstallSymlink.cmake)
@@ -2088,7 +2088,11 @@ function(llvm_install_library_symlink name dest type)
   endif()
 
   set(full_name ${CMAKE_${type}_LIBRARY_PREFIX}${name}${CMAKE_${type}_LIBRARY_SUFFIX})
-  set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX})
+  if (ARG_SOVERSION)
+    set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX}.${ARG_SOVERSION})
+  else()
+    set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX})
+  endif()
 
   if(LLVM_USE_SYMLINKS)
     set(LLVM_LINK_OR_COPY create_symlink)
diff --git a/llvm/tools/llvm-shlib/CMakeLists.txt b/llvm/tools/llvm-shlib/CMakeLists.txt
index 09c15e304614c4..eba1672faee7fa 100644
--- a/llvm/tools/llvm-shlib/CMakeLists.txt
+++ b/llvm/tools/llvm-shlib/CMakeLists.txt
@@ -35,8 +35,8 @@ if(LLVM_BUILD_LLVM_DYLIB)
   endif()
   add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB OUTPUT_NAME LLVM ${INSTALL_WITH_TOOLCHAIN} ${SOURCES})
   # Add symlink for backwards compatibility with old library name
-  get_target_property(LLVM_DYLIB_FILENAME LLVM OUTPUT_NAME)
-  llvm_install_library_symlink(LLVM-${LLVM_VERSION_MAJOR}${LLVM_VERSION_SUFFIX} ${LLVM_DYLIB_FILENAME} SHARED COMPONENT LLVM)
+  get_target_property(LLVM_DYLIB_SOVERSION LLVM SOVERSION)
+  llvm_install_library_symlink(LLVM-${LLVM_VERSION_MAJOR}${LLVM_VERSION_SUFFIX} LLVM SHARED COMPONENT LLVM SOVERSION ${LLVM_DYLIB_SOVERSION})
 
   list(REMOVE_DUPLICATES LIB_NAMES)
   if("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")

>From 3623f6eefdbc08750de58a336499c10d18b02f92 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Thu, 22 Feb 2024 21:40:13 +0000
Subject: [PATCH 2/3] Fix typo

---
 llvm/cmake/modules/AddLLVM.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index abd119f46aeb80..b766d84bc252f3 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -2074,7 +2074,7 @@ function(add_lit_testsuites project directory)
 endfunction()
 
 function(llvm_install_library_symlink name dest type)
-  cmake_parse_arguments(ARG "COMPONENT" "SOVERSION" ${ARGN})
+  cmake_parse_arguments(ARG "" "COMPONENT;SOVERSION" ${ARGN})
   foreach(path ${CMAKE_MODULE_PATH})
     if(EXISTS ${path}/LLVMInstallSymlink.cmake)
       set(INSTALL_SYMLINK ${path}/LLVMInstallSymlink.cmake)

>From 208c65bdf093417a69f1ac0c591e242597cb65c9 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Thu, 22 Feb 2024 22:06:09 +0000
Subject: [PATCH 3/3] Fix typo

---
 llvm/cmake/modules/AddLLVM.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index b766d84bc252f3..3bc78b0dc9355a 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -2074,7 +2074,7 @@ function(add_lit_testsuites project directory)
 endfunction()
 
 function(llvm_install_library_symlink name dest type)
-  cmake_parse_arguments(ARG "" "COMPONENT;SOVERSION" ${ARGN})
+  cmake_parse_arguments(ARG "" "COMPONENT;SOVERSION" "" ${ARGN})
   foreach(path ${CMAKE_MODULE_PATH})
     if(EXISTS ${path}/LLVMInstallSymlink.cmake)
       set(INSTALL_SYMLINK ${path}/LLVMInstallSymlink.cmake)