Feature request: -ast-dump-filter for file paths

We're currently using Clang's -ast-dump to extract some information out of our headers. If the STL headers get included, this is hundreds of MiBs of JSON data. But we only care about the declarations from our own files, not the system headers.

I saw there is a -ast-dump-filter flag, but that assumes we already know the symbol names we want. Could there be a version of -ast-dump-filter that instead takes a file pattern for where the decl comes from?

Start by reviewing Clang's existing -ast-dump-filter behavior and the AST-dump command path, then determine how declaration source paths and file patterns should be matched. Done means a file-pattern form can limit dumped declarations to the requested project files while avoiding system-header output, with coverage for the behavior.

Written by the indexing model from the issue text.