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Java: Update Annotation predicate examples in language guide #17026

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6 changes: 3 additions & 3 deletions docs/codeql/codeql-language-guides/annotations-in-java.rst
Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,7 @@ As a first step, let's write a query that finds all ``@Override`` annotations. A

As always, it is a good idea to try this query on a CodeQL database for a Java/Kotlin project to make sure it actually produces some results. On the earlier example, it should find the annotation on ``Sub1.m``. Next, we encapsulate the concept of an ``@Override`` annotation as a CodeQL class:

::
.. code-block:: ql

class OverrideAnnotation extends Annotation {
OverrideAnnotation() {
Expand Down Expand Up @@ -213,11 +213,11 @@ To do so, we first introduce a class for representing all ``@SuppressWarnings``
class SuppressDeprecationWarningAnnotation extends Annotation {
SuppressDeprecationWarningAnnotation() {
this.getType().hasQualifiedName("java.lang", "SuppressWarnings") and
this.getAValue().(Literal).getLiteral().regexpMatch(".*deprecation.*")
this.getAStringArrayValue("value").regexpMatch(".*deprecation.*")
}
}

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.

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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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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