RFR(L) 8136930: Simplify use of module-system options by custom launchers

[harold seigel]

Hi Dan,

This was discussed today and it was decided the the JVM will issue 
warnings if these specific properties are specified on the command line, 
provided that option PrintWarnings is TRUE.  This will probably be done 
as a separate bug.

Thanks, Harold


On 7/20/2016 3:42 PM, Daniel D. Daugherty wrote:
> On 7/17/16 5:05 PM, harold seigel wrote:
>> Hi,
>>
>> Please review these Hotspot VM only changes to process the seven 
>> module-specific options that have been renamed to have gnu-like 
>> names.  JDK changes for this bug will be reviewed separately.
>>
>> Descriptions of these options are here 
>> <http://openjdk.java.net/jeps/293>.  For these six options, 
>> --module-path, --upgrade-module-path, --add-modules, --limit-modules, 
>> --add-reads, and --add-exports, the JVM just sets a system property.  
>> For the --patch-module option, the JVM sets a system property and 
>> then processes the option in the same way as when it was named -Xpatch.
>>
>> Additionally, the JVM now checks properties specified on the command 
>> line.  If a property matches one of the properties used by one of the 
>> above options then the JVM ignores the property. This forces users to 
>> use the explicit option when wanting to do things like add a module 
>> or a package export.
>
> Based on conversations with Harold, the JVM will _silently_ ignore the
> specific properties if they are specified on the command line. Silently
> ignoring the properties will likely lead to bugs being filed even if we
> put a line or two in a man page somewhere. It seems useful for us to
> issue a warning or an error if the user tries to specify properties on
> the command line that we don't want to be specified.
>
> I poked around the bugs and I don't see a rationale for the silently
> ignore behavior. Can someone please explain?
>
> Dan
>
>
>>
>> The RFR contains two new tests.  Also, many existing tests were 
>> changed to use the new option names.
>>
>> JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8136930
>>
>> Webrev: http://cr.openjdk.java.net/~hseigel/bug_8136930.hs/
>>
>> The changes were tested with the JCK lang and VM tests, the JTreg 
>> hotspot tests, and the RBT hotspot nightlies.
>>
>> Thanks, Harold
>