Pending Character-related work - Character-warnings

[Ulf Zibis]

Jonathan,

much thanks.

My question is not about the generated parts, it's about following lines

  652         private static Map<String, UnicodeBlock>  map
  653             = new HashMap<String, UnicodeBlock>(256);

in 
http://cr.openjdk.java.net/~martin/webrevs/openjdk7/Character-warnings/src/share/classes/java/lang/Character.java.sdiff.html 

where JDK-7 compiler returns a warning: "redundant type arguments in new 
expression (use diamond operator instead).".

If coded as:

  652         private static Map<String, UnicodeBlock>  map  = new 
HashMap<>(256);

Martin said, this doesn't work, because j.l.Character must be compilable 
by the bootstrap JDK which is JDK-6.
This I don't understand in reference to what you said: "... and all the 
code in the jdk/ repo can be built with the latest language features."

-Ulf



Am 02.07.2010 01:22, schrieb Jonathan Gibbons:
> Ulf,
>
> As complicated as the build is now, it used to be way more 
> complicated.  I suspect you're just seeing a bit of history leaking 
> into that part of the build.   Because some of the code in the 
> java.lang.Character area is automatically generated, it has its own 
> special Makefile rules, so I suspect it has slipped through the cracks 
> to make sure the files that get generated are compiled with the latest 
> compiler to -target 7 class files.
>
> -- Jon
>
>
> On 07/01/2010 04:11 PM, Ulf Zibis wrote:
>> Jonathan, Kelly,
>>
>> thanks for your short but excellent descriptive explanation.
>> It mainly reflects how I understood the build process in general.
>> Can you briefly answer my questions below?
>>
>> Am 01.07.2010 18:13, schrieb Kelly O'Hair:
>>>
>>> On Jul 1, 2010, at 7:56 AM, Jonathan Gibbons wrote:
>>>
>>>> On 07/01/2010 01:32 AM, Ulf Zibis wrote:
>>>>> Am 01.07.2010 09:38, schrieb Martin Buchholz:
>>>>>> On Wed, Jun 30, 2010 at 23:49, Ulf Zibis<Ulf.Zibis at gmx.de>  wrote:
>>>>>>> Am 30.06.2010 19:50, schrieb Martin Buchholz:
>>>>>>>> On Wed, Jun 30, 2010 at 01:22, Ulf Zibis<Ulf.Zibis at gmx.de>    
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Am 29.06.2010 02:29, schrieb Martin Buchholz:
>>>>>>>>>> I tried to do that, but Character.java is one of those classes
>>>>>>>>>> that needs to be compilable by the bootstrap JDK,
>>>>>>>>>> so this change ist leider nicht moeglich.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> I think, there should be a note about this in the sources of 
>>>>>>>>> those
>>>>>>>>> classes.
>>>>>>>>>
>>>>>>>> Such a note is likely to become obsolete soon.
>>>>>>>>
>>>>>>> How do you mean that? Will the build procedure change soon. Then 
>>>>>>> it would be
>>>>>>> anyway appropriate to update to new "style".
>>>>>> In jdk8, the bootstrap jdk will be at least jdk7.
>>>>>
>>>>> It would make me wonder if there wont come new language extensions.
>>>>> I was thinking about a comment (in all bootstrap compiled classes) 
>>>>> which couldn't become obsolete like:
>>>>> "Don't use latest language extensions in this class. It's one of 
>>>>> those which must be compilable by the bootstrap JDK while building 
>>>>> this JDK. Add @suppressWarnings if appropriate."
>>>>>
>>>>> Anyway, couldn't we use the latest existing JDK-7 build for 
>>>>> bootstrap? Then we could update the sources 2 weeks later.
>>>>> ... or use 2 versions for bootstrap and library as said before.
>>>>>
>>>>> -Ulf
>>>>>
>>>>>
>>>>
>>>> Ulf,
>>>>
>>>> I suggest you go read blogs by Kelly (http://blogs.sun.com/kto/) 
>>>> and myself (http://blogs.sun.com/jjg/) on the process of building 
>>>> the JDK. The boot JDK is always the latest available FCS product 
>>>> (i.e JDK 6 for JDK 7), but the first thing done in the build is to 
>>>> build a hybrid javac that runs on the boot JDK and which 
>>>> understands the latest language.  Therefore, with the exception of 
>>>> javac and related tools that are used during the bootstrap (e.g. 
>>>> javah) most of the JDK, and all the code in the jdk/ repo can be 
>>>> built with the latest language features.
>>
>> I understand this, that all classes in jdk7/tl are compiled by 
>> source=7 level.
>> Is that correct?
>> In particular, why should j.l.Character then be compilable by 
>> source=6 level, as Martin said?
>> If so, is it thinkable to have 2 versions, one for the bootstrap and 
>> one for the final JDK7 library, so the latter would be "clean" for 
>> the source=7 level?
>>
>> -Ulf
>>
>>
>>>>
>>>> There may however be historical reasons why some classes still get 
>>>> special treatment; those would need to be examined on a case by 
>>>> case basis.
>>>>
>>>
>>> I think some of the source generation tools may require a 'dumbing 
>>> down' of the source, I forget the exact details.
>>>
>>> The jdk/make/tools/src tools are supposed to be built with the BOOT 
>>> jdk (jdk6), and in general are small utility tools
>>> that need to be run before the jdk7 image exists, but are not 
>>> technically part of the jdk7 image.
>>> So like langtools, they need to be BOOT jdk flavored sources, or 
>>> have a way to run with a BOOT jdk.
>>>
>>> -kto
>>>
>>>> -- Jon
>>>>
>>>
>>>
>>>
>>
>
>
>