RFR: 8366028: MethodType::fromMethodDescriptorString should not throw UnsupportedOperationException for invalid descriptors

[Jorn Vernee]

On Sat, 23 Aug 2025 01:46:14 GMT, Chen Liang <liach at openjdk.org> wrote:

> A previous cleanup #14642 accidentally omitted the fact that an `Array.newInstance` call in `BytecodeDescriptor::parseSig` is intended to propagate `IllegalArgumentException` to `MethodType::fromMethodDescriptorString`. This bug is discovered in a recent cleanup for `BytecodeDescriptor` in #24978.
> 
> Instead of restoring the original `newInstance` call, this patch catches the `UnsupportedOperationException` thrown by `Class::arrayType` to because the cause IAE thrown by `newInstance` has no message at all. The existing reporting system in `BytecodeDescriptor::parseMethod` includes the whole malformed descriptor string in the error message, which can be triggered by returning `null` in `parseSig`.

Looks good

test/jdk/java/lang/invoke/MethodTypeTest.java line 232:

> 230:                 "(" + "[".repeat(256) + "J)I",
> 231:                 "(java/lang/Object)V",
> 232:         };

Maybe add a case with a bad return type as well?

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Marked as reviewed by jvernee (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26909#pullrequestreview-3151195935
PR Review Comment: https://git.openjdk.org/jdk/pull/26909#discussion_r2297954343