JDK-8231433 : 1.5: Robust handling of code using essential APIs associated with preview features
  • Type: Enhancement
  • Component: specification
  • Sub-Component: language
  • Affected Version: 13
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2019-09-24
  • Updated: 2020-07-15
  • Resolved: 2019-12-23
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JDK 14
14Fixed
Related Reports
Relates :  
JDK-8229211 - 9.6.4.10: PreviewFeature
Relates :  
JDK-8231147 - 9.6.4.5: Clarify that @SuppressWarnings requires unknown strings to be ignored
Relates :  
JDK-8195734 - JEP 12: Preview Features
Relates :  
JDK-8231411 - Improve javac messages for using an API associated with a preview feature
Relates :  
JDK-8249554 - 1.5: Expand preview features to include preview APIs
Description
Per http://openjdk.java.net/jeps/12#Relationship-to-Java-SE-APIs:

- The use of an essential API element associated with a preview feature must cause either a compile-time error or a suppressible warning, depending on whether preview features are disabled or enabled respectively. JLS 1.5 must specify the presence of the error/warning, and enumerate which types/methods in Java SE 14 cause it. JLS 9.6.4.5 must record that the warning is suppressible via `@SuppressWarnings("preview")`.

- The use of a reflective API element associated with a preview feature is worthy of a warning regardless of whether preview features are disabled or enabled -- but technically this is a compiler-specific warning, not a JLS-mandated warning. Reflective APIs, whether in java.*, javax.*, or com.sun.source.*, are outside the JLS's scope.