RFR: 8365878: jshell TOOLING's javap should use binary names

[altrisi]

On Wed, 20 Aug 2025 16:14:34 GMT, Chen Liang <liach at openjdk.org> wrote:

>> This PR makes TOOLING.jsh's `javap` function support anonymous, local and built-in nested classes.
>> 
>> Note that nested classes created in jshell would previously work, but not JDK ones as they'd miss the is built-in check (wrong name for `Class.forName`) and later throw an exception because of a null classloader.
>> 
>> The rest of classes would fail the canonical name check, which wouldn't allow them to be disassembled.
>> 
>> This change makes them work by changing the check from canonicalName != null to specific checks for unsupported types of classes, and doing Class.forName using the result of getName(), not the canonical name, for the built-in check.
>
> test/langtools/jdk/jshell/ToolingTest.java line 100:
> 
>> 98:             a -> assertCommand(a, "/open TOOLING",
>> 99:                         ""),
>> 100:             a -> assertCommandUserOutputContains(a, "javap(Class.forName(\"sun.util.PreHashedMap$1\"))", // arbitrary built-in anonymous class
> 
> I recommend the case to test against a generic class without a canonical name, such as `java.lang.invoke.DirectMethodHandle$Holder` generated by jlink; arbitrary javac artifacts is subject to renames because they have no linkage exposure, and these generic packages with antique code may be removed in a future maintenance and cause unexpected failures.

`java.lang.invoke.DirectMethodHandle$Holder` seems to have a canonical name, it's not anonymous:


jshell> Class.forName("java.lang.invoke.DirectMethodHandle$Holder").getCanonicalName()
$13 ==> "java.lang.invoke.DirectMethodHandle$Holder"
jshell> Class.forName("java.lang.invoke.DirectMethodHandle$Holder").isAnonymousClass()
$14 ==> false


Wasn't too sure on this test either way, considering I also added a test for user created anonymous classes, I think I'll just remove it instead. Any anonymous class can be refactored anytime and would have the same problem.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26864#discussion_r2288746130