Java: Update Annotation predicate examples in language guide
#17026
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Marcono1234
commented
Jul 21, 2024
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| Here, we use ``getAValue()`` to retrieve any annotation value: in fact, annotation type ``SuppressWarnings`` only has a single annotation element, so every ``@SuppressWarnings`` annotation only has a single annotation value. Then, we ensure that it is a literal, obtain its string value using ``getLiteral``, and check whether it contains the string ``deprecation`` using a regular expression match. | ||
| Here, we use ``getAStringArrayValue("value")`` to retrieve any of the suppressed warnings: ``@SuppressWarnings`` defines the warnings to suppress using the annotation element named ``value`` of type ``String[]``, and ``getAStringArrayValue`` retrieves all of the array values; the CodeQL class ``Annotation`` also has similar convenience predicates for the other possible annotation element types. Afterwards we check whether one of the values is the string ``deprecation`` using a regular expression match. | ||
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| For real-world use, this check would have to be generalized a bit: for example, the OpenJDK Java compiler allows ``@SuppressWarnings("all")`` annotations to suppress all warnings. We may also want to make sure that ``deprecation`` is matched as an entire word, and not as part of another word, by changing the regular expression to ``".*\\bdeprecation\\b.*"``. |
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Side note: Not completely sure why a regex match is performed here in the first place. Maybe the original author thought the suppressions were a single String instead of a String[]?
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| Here, we use ``getAValue()`` to retrieve any annotation value: in fact, annotation type ``SuppressWarnings`` only has a single annotation element, so every ``@SuppressWarnings`` annotation only has a single annotation value. Then, we ensure that it is a literal, obtain its string value using ``getLiteral``, and check whether it contains the string ``deprecation`` using a regular expression match. | ||
| Here, we use ``getAStringArrayValue("value")`` to retrieve any of the suppressed warnings: ``@SuppressWarnings`` defines the warnings to suppress using the annotation element named ``value`` of type ``String[]``, and ``getAStringArrayValue`` retrieves all of the array values; the CodeQL class ``Annotation`` also has similar convenience predicates for the other possible annotation element types. Afterwards we check whether one of the values is the string ``deprecation`` using a regular expression match. | ||
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| For real-world use, this check would have to be generalized a bit: for example, the OpenJDK Java compiler allows ``@SuppressWarnings("all")`` annotations to suppress all warnings. We may also want to make sure that ``deprecation`` is matched as an entire word, and not as part of another word, by changing the regular expression to ``".*\\bdeprecation\\b.*"``. |
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Side note:
the OpenJDK Java compiler allows
@SuppressWarnings("all")annotations to suppress all warnings
This seems to be incorrect, javac does not support the value "all" but many IDEs support it, see JDK-7141469.
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#6246 added new predicates and deprecated some of the existing predicates, including
getAValue()which is currently used in the example.Please let me know if the new documentation text is too verbose or if I should adjust it in some way.