JDK 9 RFR for JDK-8028543 Add SourceVersion.RELEASE_9

[Joseph Darcy]

Hi Martin,

On 12/6/2013 2:31 PM, Martin Buchholz wrote:
> We have found as users of this API, that these incrementing RELEASE_ 
> constants were not helpful.  If code supported jdkN and jdkN+1, it 
> couldn't claim to support jdkN+1 because that would not compile with 
> jdkN, since the corresponding RELEASE_N+1 symbol was not defined in 
> jdkN.  We felt compelled to rewrite code to always claim to support 
> the "latest" release.
>
> Perhaps it would work if you added RELEASE_XX for releases far into 
> the future.  But you can't go back and update all the old JDKs now. 
>  They've left the barn.
>
> Or perhaps we were using the API incorrectly.  Are we missing 
> something obvious?  I'm hardly the expert...

If you have taken the trouble to make a processor robust in the face of 
unknown future language versions, then returning latest is the right 
thing to do. However, this can be a nontrivial amount of extra work.

If you are in a situation where you are supporting N and N+1 only and 
want to run on either N or N+1 (and nothing else), you would just need 
to use a construct without direct reference to N+1 for the processor to 
communicate with the environment. You could so something a bit ugly like

if (SourceVersion.latest() > RELEASE_N)
     // Return RELEASE_(N+1) with a direct reference to RELEASE_(N+1)
     return SourceVersion.value()[RELEASE_N.ordinal()+1];
else
     return RELEASE_N;

HTH,

-Joe

>
>
>
> On Fri, Dec 6, 2013 at 2:11 PM, Joseph Darcy <joe.darcy at oracle.com 
> <mailto:joe.darcy at oracle.com>> wrote:
>
>     Hello,
>
>     With JDK 9 going to get underway soon, please review the patch
>     below to address
>
>         JDK-8028543 Add SourceVersion.RELEASE_9
>     https://bugs.openjdk.java.net/browse/JDK-8028543
>
>     http://cr.openjdk.java.net/~darcy/8028543.0/
>     <http://cr.openjdk.java.net/%7Edarcy/8028543.0/>
>
>     Thanks,
>
>     -Joe
>
>     --- old/src/share/classes/javax/lang/model/SourceVersion.java
>     2013-12-06 14:06:51.000000000 -0800
>     +++ new/src/share/classes/javax/lang/model/SourceVersion.java
>     2013-12-06 14:06:51.000000000 -0800
>     @@ -55,6 +55,7 @@
>           * 1.6: no changes
>           * 1.7: diamond syntax, try-with-resources, etc.
>           * 1.8: lambda expressions and default methods
>     +     * 1.9: To be determined
>           */
>
>          /**
>     @@ -138,7 +139,15 @@
>           * Additions in this release include lambda expressions and
>     default methods.
>           * @since 1.8
>           */
>     -    RELEASE_8;
>     +    RELEASE_8,
>     +
>     +    /**
>     +     * The version recognized by the Java Platform, Standard Edition
>     +     * 9.
>     +     *
>     +     * @since 1.9
>     +     */
>     +     RELEASE_9;
>
>          // Note that when adding constants for newer releases, the
>          // behavior of latest() and latestSupported() must be updated
>     too.
>     @@ -149,21 +158,23 @@
>           * @return the latest source version that can be modeled
>           */
>          public static SourceVersion latest() {
>     -        return RELEASE_8;
>     +        return RELEASE_9;
>          }
>
>          private static final SourceVersion latestSupported =
>     getLatestSupported();
>
>          private static SourceVersion getLatestSupported() {
>              try {
>     -            String specVersion =
>     System.getProperty("java.specification.version");
>     -
>     -            if ("1.8".equals(specVersion))
>     +            switch
>     (System.getProperty("java.specification.version")) {
>     +            case "1.9":
>     +                return RELEASE_9;
>     +            case "1.8":
>                      return RELEASE_8;
>     -            else if("1.7".equals(specVersion))
>     +            case "1.7":
>                      return RELEASE_7;
>     -            else if("1.6".equals(specVersion))
>     +            case "1.6":
>                      return RELEASE_6;
>     +            }
>              } catch (SecurityException se) {}
>
>              return RELEASE_5;
>     @@ -269,7 +280,6 @@
>           * @return {@code true} if {@code s} is a keyword or literal,
>     {@code false} otherwise.
>           */
>          public static boolean isKeyword(CharSequence s) {
>     -        String keywordOrLiteral = s.toString();
>     -        return keywords.contains(keywordOrLiteral);
>     +        return keywords.contains(s.toString());
>          }
>      }
>     --- old/test/tools/javac/processing/model/TestSourceVersion.java
>     2013-12-06 14:06:51.000000000 -0800
>     +++ new/test/tools/javac/processing/model/TestSourceVersion.java
>     2013-12-06 14:06:51.000000000 -0800
>     @@ -1,5 +1,5 @@
>      /*
>     - * Copyright (c) 2011, Oracle and/or its affiliates. All rights
>     reserved.
>     + * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All
>     rights reserved.
>       * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>       *
>       * This code is free software; you can redistribute it and/or
>     modify it
>     @@ -23,7 +23,7 @@
>
>      /*
>       * @test
>     - * @bug 7025809
>     + * @bug 7025809 8028543
>       * @summary Test latest and latestSupported
>       * @author  Joseph D. Darcy
>       */
>     @@ -36,8 +36,8 @@
>       */
>      public class TestSourceVersion {
>          public static void main(String... args) {
>     -        if (SourceVersion.latest() != RELEASE_8 ||
>     -            SourceVersion.latestSupported() != RELEASE_8)
>     +        if (SourceVersion.latest() != RELEASE_9 ||
>     +            SourceVersion.latestSupported() != RELEASE_9)
>                  throw new RuntimeException("Unexpected release
>     value(s) found:\n" +
>                                             "latest:\t" +
>     SourceVersion.latest() + "\n" +
>                                             "latestSupported:\t" +
>     SourceVersion.latestSupported());
>
>

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