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Clément Fournier
2024-04-05 15:59:12 +02:00
parent 277601f9ec
commit 6f1f72de1e
1 changed files with 9 additions and 1 deletions
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pmd-java/src/main/java/net/sourceforge/pmd/lang/java/types/TypeSystem.java
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@ -697,12 +697,20 @@ public final class TypeSystem {
* <li>The intersection has a single component that is a
* class, array, or type variable. If all components are interfaces,
* then that component is {@link #OBJECT}.
* <li>If several components are arrays, then their components
* are intersected: {@code A[] & B[] = (A & B)[]}
* </ul>
*
* <p>If after these transformations, only a single component remains,
* then that is the returned type. Otherwise a {@link JIntersectionType}
* is created. Note that the intersection may be unsatisfiable (eg {@code A[] & Runnable}),
* but we don't attempt to minimize this to {@link #NULL_TYPE}.
* but we don't attempt to minimize this to {@link #NULL_TYPE}. Similarly,
* we do not attempt to minimize valid intersections. For instance {@code List<?> & Collection<Number>}
* can technically be minimized to {@code List<Number>}, but doing this
* requires inference of a fitting parameterization in general, which is
* complex, and not necessary in the internal tasks where intersection types are
* useful. In fact intersection types are precisely useful because they are
* simple to build.
*
* <p>See also JLS§4.9 (Intersection types).
*