I'm using Mac to compile "rewritersample.cpp" from https://github.com/eliben/llvm-clang-samples/tree/master/src_clang with clang and I get the following error,
fatal error: 'clang/AST/ASTConsumer.h' file not found
I don't know why I'm getting this error even though I have clang installed on my Mac.
I was getting the same error and I fixed it by installing the libclang-dev library for the version of clang/llvm I was using.
On Linux with LLVM version 5.0 that was (not sure what the command is on a mac - sorry):
sudo apt-get install libclang-5.0-dev
Note that the documentation suggests that these examples are designed to be run with a version of llvm/clang that you have built from source (either by downloading a tarred release or cloning the llvm repository). I was able to get them to build exclusively from a version of LLVM and Clang I installed via my package manager. I had to set the configuration variables for the Makefile as follows:
CXX := /usr/bin/clang++
LLVM_SRC_PATH := /usr/lib/llvm-5.0
LLVM_BUILD_PATH := /usr/lib/llvm-5.0/build
LLVM_BIN_PATH := /usr/lib/llvm-5.0/bin
Again, it's probably a little different on a mac, but hopefully this can help point you in the right direction.