RFR: 8258061: Improve diagnostic information about errors during class redefinition

[Chris Plummer]

On Thu, 17 Dec 2020 05:27:36 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> The error code during class redefinition might be not enough to easily diagnose the problem. Some more logging might be useful to understand it. I encountered this problem when redefined methods with lambda usage.
>> I run all existing tests with enabled logging and sanity verified error messages.
>
> src/hotspot/share/prims/jvmtiRedefineClasses.cpp line 936:
> 
>> 934:        scratch_class->super()->name())) {
>> 935:     log_trace(redefine, class, normalize)
>> 936:       ("redefined class %s superclass change error: superclass changed from %s to %s.",
> 
> I'm not so sure I like the style of the log message wording. I would prefer something like:
> 
>      error redefining class %s: superclass changed from %s to %s.
> 
> The same comment applies to pretty much every error message below. Besides being more concise and easier to read, I don't like using "superclass change error" when there is no such formally defined error. The error is `JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED`.

I see now that you are just being consistent with the style used in existing logs, so I guess it's ok.

-------------

PR: https://git.openjdk.java.net/jdk/pull/1811