RFR: JDK-8226585: Improve javac messages for using a preview API

[Jan Lahoda]

Thanks for the new code Erik!

A new webrev/patch that includes this better way of copying is here:
http://cr.openjdk.java.net/~jlahoda/8226585/webrev.01/

Any feedback is welcome!

Thanks,
     Jan

On 03. 10. 19 18:06, Erik Joelsson wrote:
> Hello Jan,
> 
> The build change looks ok, but I would recommend this construct for 
> copying the file instead:
> 
> $(eval $(call SetupCopyFiles, COPY_PREVIEW_FEATURES, \
>      FILES := 
> $(TOPDIR)/src/java.base/share/classes/jdk/internal/PreviewFeature.java, \
>      DEST := 
> $(BUILDTOOLS_OUTPUTDIR)/gensrc/java.base.interim/jdk/internal/PreviewFeature.java, 
> \
> ))
> 
> TARGETS += $(COPY_PREVIEW_FEATURES)
> 
> Then you automatically get all the corner case handling we have 
> implemented over the years for logging, making directories and copying 
> files. Your version is still correct for this case though.
> 
> /Erik
> 
> On 2019-10-03 02:57, Jan Lahoda wrote:
>> Hi,
>>
>> This is a continuation of Joe's patch from here:
>> https://mail.openjdk.java.net/pipermail/compiler-dev/2019-June/013498.html 
>>
>>
>> APIs associated with preview features are split into two groups: 
>> essential and non-essential. These are marked with an JDK-internal 
>> annotation, PreviewFeature, and a tag in the javadoc, @preview. The 
>> javac follows the PreviewFeature annotation, and produces either 
>> warnings or errors for the usages of such APIs. For the @preview tag, 
>> there is a taglet in the JDK build that adds the content of the tag 
>> into the documentation. The first part of the @preview's text goes 
>> into the summary, the second part goes into the detailed description.
>>
>> For build, a tricky problem is that the jdk.compiler module uses the 
>> PreviewFeature annotation as well, but that is not in the bootstrap 
>> JDK. So, for the intermediate langtools build, the PreviewFeature 
>> annotation is copied from java.base.
>>
>> Proposed webrev:
>> http://cr.openjdk.java.net/~jlahoda/8226585/webrev.00/
>>
>> Javadoc with the change:
>> http://cr.openjdk.java.net/~jlahoda/8226585/docs.00/api/index.html
>>
>> See for example:
>> http://cr.openjdk.java.net/~jlahoda/8226585/docs.00/api/java.base/java/lang/String.html 
>>
>> http://cr.openjdk.java.net/~jlahoda/8226585/docs.00/api/jdk.compiler/com/sun/source/tree/CaseTree.html 
>>
>>
>> JBS:
>> https://bugs.openjdk.java.net/browse/JDK-8226585
>>
>> CSR:
>> https://bugs.openjdk.java.net/browse/JDK-8231411
>>
>> Feedback is welcome!
>>
>> Thanks,
>>     Jan