RFR: 8342206: Convenience method to check if a constant pool entry matches nominal descriptors

[Chen Liang]

On Tue, 11 Feb 2025 08:03:23 GMT, Adam Sotona <asotona at openjdk.org> wrote:

>> The ClassFile API promotes usage of constant nominal descriptors over literal strings. However, for `class` file parsing, currently the efficient way to check if a constant pool entry matches a desired descriptor is via unrolling them back to strings. However, string unrolling is ugly, and often times confusing, such as internal names versus field descriptors.
>> 
>> As a result, I propose to provide new methods that compare constant pool entries with the potential symbolic descriptors they represent. This is no less efficient as checking raw string equality, avoids exceptional failure behaviors of conversion to symbolic descriptors, and avoids potential programmer errors stemming from raw string handling. See the CSR for a full story.
>
> src/java.base/share/classes/java/lang/classfile/constantpool/Utf8Entry.java line 95:
> 
>> 93:      * @since 25
>> 94:      */
>> 95:     boolean equalsSymbol(ClassDesc desc);
> 
> Ambiguity of class internal name vs. descriptor serialization might be confusing:
> 
> classEntry.equalsSymbol(classDesc) != classEntry.name().equalsSymbol(classDesc)
> 
> I think it should be more highlighted to avoid mistakes.

I think the best way to avoid these confusions is, in addition to specifying in the docs, renaming the methods on `Utf8Entry` to include the word "descriptor", like `equalsDescriptorString`, but I fear this method name might be too long.

If the `equalsDescriptorString` on `Utf8Entry` is too inconvenient, a remedy may be to add `matches(String, ClassDesc)` or `matches(String, MethodTypeDesc)` to NameAndTypeEntry and/or MemberRefEntry.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23548#discussion_r1951191457