Clang Frontend

Capturing source files

Start at ClangFrontend.Capture for how Infer uses Clang to parse source files, using our Clang plugin. For more information on our clang plugin itself, refer to the relevant documentation in facebook-clang-plugins:

• facebook-clang-plugins/libtooling/ATD_GUIDELINES.md
• facebook-clang-plugins/clang-ocaml/README.md

Quick guide to changing the AST format

1. Create a simple example (example.cpp) source file with construct that needs to be exported. The smaller the better.
2. Export the extra information by changing the code in libtooling/ASTExporter.h. For more information, refer to the ATD_GUIDELINES.
3. Compile Infer with the new version of facebook-clang-plugins. Running make from top level of Infer repository will do that. Sometimes there may be compilation errors due to .atd file changes --they need to be fixed.
4. Use newly-exported information in the frontend as you please.

Tips & Tricks

• To view the AST in a human readable version, Infer can generate .bdump files: infer -g -- clang -c example.cpp && sh example.cpp.ast.sh. Then open example.cpp.ast.bdump.
• To inspect the AST visually: clang -c example.cpp -Xclang -ast-dump. It doesn't include all the information that Infer sees, but it's often a good place to start.
• If running bdump is failing (it happens on huge sources sometimes), there is a way to view it in "Yojson" format. To do that, replace all occurrences of BiniouASTExporter with YojsonASTExporter in the .ast.sh debug script.