build: fix clang 10 build

some distros already packaging clang 10 (checked fedora and arch) no longer
ship all the individual libclang*.so component libraries.
Instead, clang from 9.0 onwards provides a new lib, libclang-cpp.so, which
includes everything we need.

Tell cmake to use it if the individual libraries are no longer found.
(Build-wise, if both are present it is more efficient to use the individual
components so keep these first)

CMakeLists.txt

@@ -55,19 +55,19 @@ endif()
 # clang is linked as a library, but the library path searching is
 # primitively supported, unlike libLLVM
 set(CLANG_SEARCH "/opt/local/llvm/lib;/usr/lib/llvm-3.7/lib;${LLVM_LIBRARY_DIRS}")
-find_library(libclangAnalysis NAMES clangAnalysis HINTS ${CLANG_SEARCH})
-find_library(libclangAST NAMES clangAST HINTS ${CLANG_SEARCH})
-find_library(libclangBasic NAMES clangBasic HINTS ${CLANG_SEARCH})
-find_library(libclangCodeGen NAMES clangCodeGen HINTS ${CLANG_SEARCH})
-find_library(libclangDriver NAMES clangDriver HINTS ${CLANG_SEARCH})
-find_library(libclangEdit NAMES clangEdit HINTS ${CLANG_SEARCH})
-find_library(libclangFrontend NAMES clangFrontend HINTS ${CLANG_SEARCH})
-find_library(libclangLex NAMES clangLex HINTS ${CLANG_SEARCH})
-find_library(libclangParse NAMES clangParse HINTS ${CLANG_SEARCH})
-find_library(libclangRewrite NAMES clangRewrite HINTS ${CLANG_SEARCH})
-find_library(libclangSema NAMES clangSema HINTS ${CLANG_SEARCH})
-find_library(libclangSerialization NAMES clangSerialization HINTS ${CLANG_SEARCH})
-find_library(libclangASTMatchers NAMES clangASTMatchers HINTS ${CLANG_SEARCH})
+find_library(libclangAnalysis NAMES clangAnalysis clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangAST NAMES clangAST clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangBasic NAMES clangBasic clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangCodeGen NAMES clangCodeGen clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangDriver NAMES clangDriver clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangEdit NAMES clangEdit clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangFrontend NAMES clangFrontend clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangLex NAMES clangLex clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangParse NAMES clangParse clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangRewrite NAMES clangRewrite clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangSema NAMES clangSema clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangSerialization NAMES clangSerialization clang-cpp HINTS ${CLANG_SEARCH})
+find_library(libclangASTMatchers NAMES clangASTMatchers clang-cpp HINTS ${CLANG_SEARCH})
 if(libclangBasic STREQUAL "libclangBasic-NOTFOUND")
   message(FATAL_ERROR "Unable to find clang libraries")
 endif()