Missing header files in AST display

I can currently successfully compile and link C and C++ code on my Windows 10 system but I would also like to be able to separately generate the AST for each file. The command line below does display much of the AST but it contains errors regarding missing header files that my files have included. For normal compiling I use the -I dir option in the standard way to specify header file paths but that does not seem to work with the command line below. How should this be done?
clang -cc1 -ast-dump test.c

Do you mean the default include paths? Not sure how the Windows
version is handling this, but if a normal clang compilation works for
you, then this should make the ast-dump working with all include
default paths:

clang -Xclang -ast-dump -fsyntax-only -I/your/usual/extra/paths test.c

Note that there is no -cc1 but instead we only add the -ast-dump to
the -cc1 invocation via -Xclang. This way you also get your default
include paths from the driver.

Otherwise you should write an example invocation that fails to find a
certain header in a certain path, because with the current information
it's hard to say what exactly is going wrong.

- Raphael