Can I add include files into preprocessor?

Before parse the source file to Clang to parse, I would like to tell Clang preprocessor to include some header files.
What I want to do is to include headers that can expand forward declaration to full declaration.

So can I add include files to preprocessor, similar as how we add defines?

Thanks

I think what you're looking for is the -include flag

From: Matthew.Arsenault@amd.com
To: wqking@outlook.com; cfe-dev@cs.uiuc.edu
Subject: RE: [cfe-dev] Can I add include files into preprocessor?
Date: Tue, 2 Jul 2013 16:29:28 +0000

I think what you're looking for is the -include flag

Exactly, thanks.
I would have a look at Clang command line options.

Another way of doing this can be to use ‘HeaderSearchOptions’ as described in the post.

http://clang-developers.42468.n3.nabble.com/unable-to-parse-header-files-td2145004.html

What is the difference between using ‘HeaderSearchOptions’ and -include flag? Is it only that we use ‘HeaderSearchOptions’ when using clang as a library and ‘-include’ when using clang as executable ?

Regards,
Pankaj

Date: Tue, 2 Jul 2013 22:38:07 -0700
From: godepankaj@yahoo.com
To: cfe-dev@cs.uiuc.edu
Subject: Re: [cfe-dev] Can I add include files into preprocessor?

Another way of doing this can be to use 'HeaderSearchOptions' as
described in the post.

http://clang-developers.42468.n3.nabble.com/unable-to-parse-header-files-td2145004.html

What is the difference between using 'HeaderSearchOptions' and -include
flag? Is it only that we use 'HeaderSearchOptions' when using clang as
a library and '-include' when using clang as executable ?

I think HeaderSearchOptions can only add include search directories rather than header files?
Also, we can use -include in libclang, there is API to parse command line arguments.