Merge branch 'feature/robust-build' into 'master'

More robust build instructions

See merge request frama-c/frama-clang!217

framaCIRGen_src/CMakeLists.txt

@@ -20,7 +20,7 @@
 #                                                                        #
 ##########################################################################
 
-cmake_minimum_required(VERSION 3.6)
+cmake_minimum_required(VERSION 3.20)
 
 project(FramaCIRGen C CXX)
 
@@ -28,6 +28,17 @@ set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+find_program(LLVM_CONFIG
+  NAMES $ENV{OPAM_LLVM_CONFIG} llvm-config llvm-config-15 llvm-config-14
+        llvm-config-13 llvm-config-12 llvm-config-11
+  REQUIRED)
+
+execute_process(COMMAND ${LLVM_CONFIG} --cmakedir OUTPUT_VARIABLE CMAKE_LLVM_PREFIX)
+
+cmake_path(GET CMAKE_LLVM_PREFIX PARENT_PATH CMAKE_LLVM_CLANG_PREFIX)
+set(Clang_DIR ${CMAKE_LLVM_CLANG_PREFIX}/clang)
+set(LLVM_DIR ${CMAKE_LLVM_CLANG_PREFIX}/llvm)
+
 find_package(Clang REQUIRED)
 find_package(LLVM REQUIRED)
 

framaCIRGen_src/build.sh

-#! /usr/bin/bash
+#! /bin/sh
 ##########################################################################
 #                                                                        #
 #  This file is part of Frama-Clang                                      #