How to view Clang AST?

Clang supports showing the AST with Graphviz's dotty -- you can grab the temporary .dot file generated (name is printed out) to get the graph source.

clang -cc1 -ast-view your_file.c

You can also print to the command line with:

clang -cc1 -ast-dump your_file.c

or:

clang -cc1 -ast-print your_file.c

or in 3.3:

clang -cc1 -ast-dump-xml your_file.c

but this was removed later as pointed by Lukas Kubanek in the comment.

The method with -cc1 invocation will have problem with includes and recognizing C++.

For full-featured parsing, use:

clang -Xclang -ast-dump file.cpp