[12] RFR (M) JDK-8205611: Improve the wording of LinkageErrors to include module and class loader information

[Lois Foltan]

On 7/5/2018 10:06 AM, Harold David Seigel wrote:

> Hi Lois,
>
> This change looks good!
>
> Can you fix the indentation at lines 523 - 525 and 1262 - 1264 in 
> klassVtable.cpp?  No need for a new webrev.

Thanks Harold for the review! I fixed the indentation.
Lois

>
> Thanks, Harold
>
>
> On 6/27/2018 9:20 AM, Lois Foltan wrote:
>> Please review this change to migrate existing loader constraint 
>> LinkageErrors to the new error message format proposal.  The actual 
>> wording of the loader constraint messages has not changed. Module and 
>> class loader information have been moved into the error message's 
>> REASON section.  This change also removes the method 
>> java_lang_ClassLoader::describe_external() in favor of 
>> Klass::class_in_module_of_loader().
>>
>> open webrev at 
>> http://cr.openjdk.java.net/~lfoltan/bug_jdk8205611/webrev/
>> bug link https://bugs.openjdk.java.net/browse/JDK-8205611
>>
>> JDK-8166633 outlines a new proposal where error messages follow a 
>> format of ERRROR: PROBLEM (REASON) where the PROBLEM is aggressively 
>> simple (and definitely avoids arbitrary-length loader names) so the 
>> REASON bears all the cost of explaining the PROBLEM with more 
>> specifics.  See the proposal in more detail at 
>> https://bugs.openjdk.java.net/browse/JDK-8166633. The new utility 
>> method Klass::class_in_module_of_loader() implements the proposed 
>> format.
>>
>> Some example text:
>>
>> (JDK 11) 'DuplicateLE_Test_Loader_IF' @<id> (instance of 
>> PreemptingClassLoader, child of 'app' 
>> jdk.internal.loader.ClassLoaders$AppClassLoader) attempted duplicate 
>> interface definition for test.J.
>> to
>> (JDK 12) loader 'DuplicateLE_Test_Loader_IF' @6eeee674 attempted 
>> duplicate interface definition for test.J. (test.J is in unnamed 
>> module of loader 'DuplicateLE_Test_Loader_IF' @6eeee674, parent 
>> loader 'app')
>>
>>
>> (JDK 11) loader constraint violation: loader PreemptingClassLoader 
>> @<id> (instance of PreemptingClassLoader, child of 'app' 
>> jdk.internal.loader.ClassLoaders$AppClassLoader) wants to load class 
>> test.D_ambgs. A different class with the same name was previously 
>> loaded by 'app' (instance of 
>> jdk.internal.loader.ClassLoaders$AppClassLoader).
>> to
>> (JDK 12) loader constraint violation: loader PreemptingClassLoader 
>> @5bc79a1c wants to load class test.D_ambgs. A different class with 
>> the same name was previously loaded by 'app'. (test.D_ambgs is in 
>> unnamed module of loader 'app')
>>
>>
>> (JDK 11) loader constraint violation for class test.Task: when 
>> selecting overriding method test.Task.m()Ltest/Foo; the class loader 
>> PreemptingClassLoader @<id> (instance of PreemptingClassLoader, child 
>> of 'app' jdk.internal.loader.ClassLoaders$AppClassLoader) of the 
>> selected method's type test.Task, and the class loader 'app' 
>> (instance of jdk.internal.loader.ClassLoaders$AppClassLoader) for its 
>> super type test.J have different Class objects for the type test.Foo 
>> used in the signature
>> to
>> (JDK 12) loader constraint violation for class test.Task: when 
>> selecting overriding method test.Task.m()Ltest/Foo; the class loader 
>> PreemptingClassLoader @7884e077 of the selected method's type 
>> test.Task, and the class loader 'app' for its super type test.J have 
>> different Class objects for the type test.Foo used in the signature 
>> (test.Task is in unnamed module of loader PreemptingClassLoader 
>> @7884e077, parent loader 'app'; test.J is in unnamed module of loader 
>> 'app')
>>
>>
>> Testing: hs-tier(1-3), jdk-tier(1-3) complete
>>                hs-tier(4,5) in progress
>>                JCK vm, lang in progress
>>
>> Thanks,
>> Lois
>