RFR: JDK-8317635: Improve GetClassFields test to verify correctness of field order [v2]

[Serguei Spitsyn]

On Wed, 18 Oct 2023 01:40:18 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

>> All test cases in getclfld007 had 1 (or 0) field in test classes/interfaces.
>> The change adds several fields in one of the test classes to verify order of the returned fields (as described by GetClassFields spec: "in the order they occur in the class file").
>> Field order in the class file is not guaranteed to be the same as in the source, so information about expected fields and expected order is extracted by ASM (it parses class file sequentially).
>> This allows to drop hardcoded field name/type in native part.
>> 
>> Additionally did some test cleanup:
>> - dropped "printdump" stuff (the test always logs reported fields);
>> - removed unused `generic` in native check() method, added deallocation of `name` and `sig`
>
> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   get field order from class file

test/hotspot/jtreg/vmTestbase/nsk/jvmti/GetClassFields/getclfld007.java line 120:

> 118:             return explorer.fieldNameAndSig;
> 119:         }
> 120:     }

Nit: I'd suggest to make get() an instance method. It will be a little bit simpler and more natural.
It wiill look as below:

    static void check(Class cls) throws Exception {
        FieldExplorer explorer = new FieldExplorer(cls);
        List<String> fields = explorer.get();
        check(cls, fields.toArray(new String[0]));
    }
    . . .
        List<String> get() throws Exception {
            System.out.println("Class " + cls.getName());
            try (InputStream classBytes = getClassBytes()) {
                ClassReader classReader = new ClassReader(classBytes);
                classReader.accept(this, 0);
            }
            return fieldNameAndSig;
        }

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PR Review Comment: https://git.openjdk.org/jdk/pull/16131#discussion_r1364717745