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

[Harold David Seigel]

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


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