Preferring class files to source files in ClassReader.java

[Jeremy Manson]

Bump, because of JDK9 opening (I somehow missed the conversation after my
last message - sorry about abandoning the thread mid-stream).

I'd say that regardless of which you choose, it should probably be
consistently preferring source or classfile.  Right now, the preference
depends on what it happens to encounter first, which is rather
unpredictable.  Anyone actually relying on this behavior is doing something
deeply brittle, since a small refactoring of their build rules can change
which they get.

Once the decision has been taken to pin it down one way or the other, I'm
not averse to a flag or something.

Jeremy


On Thu, Nov 14, 2013 at 11:22 AM, Jonathan Gibbons <
jonathan.gibbons at oracle.com> wrote:

> On 11/14/2013 11:06 AM, Joel Borggrén-Franck wrote:
>
>> On 14 nov 2013, at 19:44, Jonathan Gibbons <jonathan.gibbons at oracle.com>
>> wrote:
>>
>>  On 11/14/2013 04:03 AM, Joel Borggren-Franck wrote:
>>>
>>>> Hi Jeremy,
>>>>
>>>> On 2013-11-13, Jeremy Manson wrote:
>>>>
>>>>> Hi folks,
>>>>>
>>>>> A bit of background:
>>>>>
>>>>> - We use a content-addressable storage around here, so to minimize the
>>>>> diffs between two JAR files (and get more hits in our
>>>>> content-addressable
>>>>> storage), we reset all timestamps in JAR files to the same values.
>>>>> - Some of our users include both source and class files in their JAR
>>>>> files.
>>>>> - When those users want to put those JAR files on the classpath for
>>>>> javac,
>>>>> and use them to compile other files, they may not have included enough
>>>>> on
>>>>> the classpath to compile the source files.
>>>>> - We've worked around this by favoring classfiles when the two files
>>>>> are of
>>>>> the same age.  This has the added benefit of not having to recompile
>>>>> the
>>>>> source files when they are found.
>>>>> - What do you think?  Too esoteric?  Wait for JDK9?
>>>>>
>>>>>  Thinking out loud here. While I do understand your usecase, don't we
>>>> want the opposite to be the default case? If javac finds a source and a
>>>> class file and the timestamps are suspect isn't the responsible thing to
>>>> do to compile the source again?
>>>>
>>>> cheers
>>>> /Joel
>>>>
>>> I think Jeremy would argue that the timestamps are not suspect -- they
>>> are exactly what they have set them to be!
>>>
>>>
>> Yes, but javac doesn't know that. In order to make a change like this I
>> think you need to argue it is correct in all cases. I'm not convinced of
>> that yet, but then again I'm not yet convinced of the opposite either.
>>
>> Could be interesting to compare with how make handles equal timestamps.
>>
>> cheers
>> /Joel
>>
>
>
> I think the general take on this discussion is that in JDK 9, we should
> examine the possibility of updating -Xprefer to have more policies
> available.  I'm also open to changing existing policies -- but with some
> concern for compatibility for those who like the existing policies.
>
> -- Jon
>
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