I'm using google's cpplint.py to verify source code in my project meets the standards set forth in the Google C++ Style Guide. We use SCons to build so I'd like to automate the process by having SCons first read in all of our .h and .cc files and then run cpplint.py on them, only building a file if it passes. The issues are as follows:
- In SCons how do I pre-hook the build process? No file should be compiled until it passes linting.
- cpplint doesn't return an exit code. How do I run a command in SCons and check whether the result matches a regular expression? I.E., how do I get the text being output?
- The project is large, whatever the solution to #1 and #2 it should run concurrently when the -j option is passed to SCons.
- I need a whitelist that allows some files to skip the lint check.
One way to do this is to monkey patch the object emitter function, which turns C++ code into linkable object files. There are 2 such emitter functions; one for static objects and one for shared objects. Here is an example that you can copy paste into a SConstruct:
There's nothing too tricky about it really. You'd set LINT to the path to your cpplint.py copy, and set appropriate LINT_OPTIONS for your project. The only warty bit is creating a TARGET file if the check passes using the command line
date
program. If you want to be cross platform then that'd have to change.Adding a whitelist is now just regular Python code, something like:
It seems cpplint.py does output the correct error status. When there are errors it returns 1, otherwise it returns 0. So there's no extra work to do there. If the lint check fails, it will fail the build.
This solution works with -j, but the C++ files may compile as there are no implicit dependencies between the lint fake output and the object file target. You can add an explicit
env.Depends
in there to force that the ".lint" output depend on the object target. As is it's probably enough, since the build itself will fail (scons gives a non-zero return code) if there are any remaining lint issues even after all the C++ compiles. For completeness the depends code would be something like this in the DoLint function: