Review Request JDK-8160286: jmod hash is creating unlinkable modules.

[Mandy Chung]

Updated webrev:
   http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8160286/webrev.01/

I did a further clean up and ModuleHashesBuilder now has one constructor.
Also updated the comment to avoid using the term “base”.  Due to the 
refactoring, I moved the location of the tmp jmod file to be in the
tmp directory rather than the same directory of the jmod file; 
otherwise, it would confuse the ModuleFinder with the tmp file.

I added a few more test cases that remind me that a packaged user 
module can’t tie with a specific JDK build since a module requiring 
a JDK module that would be a leaf node of the subgraph rather than 
that module.  The `jar` tool locating JMOD files on the module path 
allows to tie a modular JAR with a module requiring it but packaged
as JMOD file (e.g. with native library).

Mandy

> On Jan 12, 2017, at 7:52 AM, Mandy Chung <mandy.chung at oracle.com> wrote:
> 
> 
>> On Jan 12, 2017, at 7:08 AM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
>> 
>> On 11/01/2017 23:47, Mandy Chung wrote:
>> 
>>> Webrev:
>>>  http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8160286/webrev.00/
>>> 
>>> jmod and jar -—hash-modules option to specify a pattern of modules
>>> to be hashed in the module M being created.  It records the modules
>>> that depend on M directly and indirectly.
>>> 
>> This looks quite good.  At some point then we'll need to move the tool support out of jdk.internal.module but is something for another day.
>> 
>> For ModuleHashesBuilder then it might be useful to put a comment on the constructors as it's not immediately obvious why both are needed. Also I wonder if we should use a term other than "base" for the modules that don't have references to other modules in the sub-graph (they are sort of leaf modules in the sub-graph).  A typo at L96 "in topological orders" -> "order”.
> 
> I’ll take a pass and update the comments.  I can see “base” can be confusing.
> 
>> One of the changes in this patch is that the `jar` tool will locate JMOD files on the module path. I assume this is to provide flexibility to those creating a modular JAR that want to tie it to a specific JDK build. I guess it's okay but I suspect will not be widely used.
> 
> Right and another case is packaged module with a native library (security providers). It will not be widey used.
> 
> Mandy