From d74b8aa8cebb24e3a2f38a9b57704756052a22b8 Mon Sep 17 00:00:00 2001
From: Jonas Hahnfeld <jonas.hahnfeld@cern.ch>
Date: Wed, 30 Apr 2025 14:39:26 +0200
Subject: [PATCH 1/2] [CMake] Fix build with LLVM_LIBDIR_SUFFIX

This allows configuring with builtin_llvm=OFF and a system-provided
LLVM with LLVM_LIBDIR_SUFFIX, for example on Alma Linux.
---
 core/clingutils/CMakeLists.txt | 2 +-
 interpreter/CMakeLists.txt     | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/core/clingutils/CMakeLists.txt b/core/clingutils/CMakeLists.txt
index ec4024f1d9b14..493c89e89141d 100644
--- a/core/clingutils/CMakeLists.txt
+++ b/core/clingutils/CMakeLists.txt
@@ -82,7 +82,7 @@ endforeach()
 
 set(CLANG_RESOURCE_DIR_STEM)
 if (builtin_clang)
-  set(CLANG_RESOURCE_DIR_STEM ${CMAKE_BINARY_DIR}/interpreter/llvm-project/llvm/${CMAKE_CFG_INTDIR}/lib/clang)
+  set(CLANG_RESOURCE_DIR_STEM ${CMAKE_BINARY_DIR}/interpreter/llvm-project/llvm/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX}/clang)
   set(CLANG_RESOURCE_DIR_VERSION ${LLVM_VERSION_MAJOR})
 else ()
   set(CLANG_RESOURCE_DIR_STEM ${LLVM_LIBRARY_DIR}/clang)
diff --git a/interpreter/CMakeLists.txt b/interpreter/CMakeLists.txt
index e6512a888284c..4f5a3d2adddda 100644
--- a/interpreter/CMakeLists.txt
+++ b/interpreter/CMakeLists.txt
@@ -266,6 +266,7 @@ else()
   # Make some LLVM variables globally available.
   set(LLVM_INCLUDE_DIRS ${LLVM_INCLUDE_DIRS} CACHE PATH "Path to llvm/include")
   set(LLVM_LIBRARY_DIR ${LLVM_LIBRARY_DIR} CACHE PATH "Path to llvm/lib")
+  set(LLVM_LIBDIR_SUFFIX ${LLVM_LIBDIR_SUFFIX} CACHE STRING "Suffix of library directory name")
 
   find_program(LLVM_TABLEGEN_EXE "llvm-tblgen" ${LLVM_TOOLS_BINARY_DIR}
     NO_DEFAULT_PATH)
@@ -403,7 +404,7 @@ if (builtin_clang)
     ${CMAKE_CURRENT_SOURCE_DIR}/llvm-project/clang/include
     ${CLANG_BINARY_DIR}/include
     CACHE STRING "Clang include directories.")
-  set(CLANG_CMAKE_DIR "${CMAKE_BINARY_DIR}/lib/cmake/clang/")
+  set(CLANG_CMAKE_DIR "${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/cmake/clang/")
 else()
   find_package(Clang REQUIRED CONFIG)
   message(STATUS "Found Clang ${CLANG_PACKAGE_VERSION} in ${CLANG_CMAKE_DIR}")

From 711ab4e8cf8cd702aa2020af780a0a184aea6641 Mon Sep 17 00:00:00 2001
From: Jonas Rembser <jonas.rembser@cern.ch>
Date: Tue, 22 Apr 2025 13:18:14 +0200
Subject: [PATCH 2/2] [CMake] Get Clang directory from `CLANG_INSTALL_PREFIX`

If Clang was installed standalone (in particular, not in the LLVM tree),
use the CLANG_INSTALL_PREFIX variable to indicate where it is.

Actually, we can always use `CLANG_INSTALL_PREFIX`. It's defined by
`ClangConfig.cmake`. To make sure that this works, `find_package(Clang)`
has to be called in `core/clingutils/CMakeLists.txt`.
---
 core/clingutils/CMakeLists.txt | 2 +-
 interpreter/CMakeLists.txt     | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/core/clingutils/CMakeLists.txt b/core/clingutils/CMakeLists.txt
index 493c89e89141d..99342dc4b16df 100644
--- a/core/clingutils/CMakeLists.txt
+++ b/core/clingutils/CMakeLists.txt
@@ -85,7 +85,7 @@ if (builtin_clang)
   set(CLANG_RESOURCE_DIR_STEM ${CMAKE_BINARY_DIR}/interpreter/llvm-project/llvm/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX}/clang)
   set(CLANG_RESOURCE_DIR_VERSION ${LLVM_VERSION_MAJOR})
 else ()
-  set(CLANG_RESOURCE_DIR_STEM ${LLVM_LIBRARY_DIR}/clang)
+  set(CLANG_RESOURCE_DIR_STEM ${CLANG_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}/clang)
   # A user can define a clang version to use, otherwise find it (but will error if more than one version is present)
   if (NOT DEFINED CLANG_RESOURCE_DIR_VERSION)
     if (NOT EXISTS ${CLANG_RESOURCE_DIR_STEM})
diff --git a/interpreter/CMakeLists.txt b/interpreter/CMakeLists.txt
index 4f5a3d2adddda..a4fc805ce41b5 100644
--- a/interpreter/CMakeLists.txt
+++ b/interpreter/CMakeLists.txt
@@ -408,6 +408,9 @@ if (builtin_clang)
 else()
   find_package(Clang REQUIRED CONFIG)
   message(STATUS "Found Clang ${CLANG_PACKAGE_VERSION} in ${CLANG_CMAKE_DIR}")
+
+  # Forward CLANG_INSTALL_PREFIX so it can be used by core/clingutils/CMakeLists.txt
+  set(CLANG_INSTALL_PREFIX ${CLANG_INSTALL_PREFIX} PARENT_SCOPE)
 endif()
 
 # Reset the compiler flags after compiling LLVM and Clang