Miscellaneous

Some students cannot access http://metaborg.org because the TU Delft DNS server fails to resolve. As a workaround you can access the documentation at http://spoofax.readthedocs.io.

Debugging

How do I know if building my language failed?

Make sure you have the console view open – use Window > Show View > Console to open it. If the build fails, the build process logs BUILD FAILED, otherwise it will show Reloading language project eclipse:///minijava.

Sometimes the build fails with the following exception:

  org.metaborg.core.MetaborgException:
    Previous build failed  and no change in the build input has been
    observed, not rebuilding. Fix the problem, or clean and rebuild
    the project to force a rebuild.

The build will run again after you clean you project.

Why do I get exceptions when hovering the file or trying to show analysis results?

Sometimes the Spoofax update seems incomplete, and you get exceptions about missing primitives (usually named something like SG_ast_...). This can be resolved by downloading a fresh Eclipse with Spoofax (see instructions).

Why do my tests fail?

There are several possible reasons why your tests do not work.

1. An error Unable to access the language under test: 'minijava'. at the top of the file means the language was not built, or the build failed (see here for more info).
2. An error Expected analysis to succeed on a test means analysis has crashed, and the test cannot be run. See here for info on analysis crashes.
3. Error Found unexpected matching messages outside the test region on the test occurs when you test for messages (e.g., no errors), but some messages of the expected severity appear in the fixture instead of the test. Because this could mean an error in the location of the messages, this is disallowed altogether.
4. The test expectation was not met. The error messages give more information on the cause (e.g., there were errors, when none were expected).

Protip: writing small example programs of the case you are investigating can be a quick way to see if your implementation behaves the way you expect.

Why does get-type fail?

If get-type fails when using the run get-type test expectation, it prints some debug information to the console that may help to resolve the problem.

If the console output says get-type: no analysis for node ...:

1. The program may have type errors. The run get-type expectation does not imply that the program is error free. Add a analysis succeeds before therun get-type to ensure there are no errors.

If the console output says get-type: no type on node ...:

1. Types may not be correctly associated with the AST nodes (using @e.type := T). See the lab description on how to do this.
2. The strategy may be run on the wrong part of the AST. Check that the node in the console error is the node that should have the type. For example, maybe get-type must be applied to a selection (with run get-type on #1 to ...) instead of on the whole fragment (with run get-type to ...).

If the console output says get-type: no className on scope ...:

1. The className relation may not be defined, or entries are not added (see lab description for details).
2. The className entries may be associated with the wrong scope. Ensure you add the className to the class scope, the one used in the class type.