On Tue, 28 Nov 2023 14:32:14 GMT, Pavel Rappo <pra...@openjdk.org> wrote:

> Please review this PR to support _JEP 463 Implicitly Declared Classes and 
> Instance Main Method (Second Preview)_ in JavaDoc.
> 
> [JEP 463](https://openjdk.org/jeps/463) is the next iteration of [JEP 
> 445](https://openjdk.org/jeps/445), which introduced the ability to have a 
> source file as a launchable, "classless" method bag
> 
> 
> % cat HelloWorld.java
> /** Run me. */
> void main() {
>     print("Hello, world!");
> }
> 
> /** Shortcut for printing strings. */
> void print(String arg) {
>     System.out.println(arg);
> }
> 
> 
> which the compiler interprets as a familiar class
> 
> 
> final class HelloWorld {
> 
>     HelloWorld() {
>     }
> 
>     /** Run me. */
>     void main() {
>         print("Hello, world!");
>     }
> 
>     /** Shortcut for printing strings. */
>     void print(String arg) {
>         System.out.println(arg);
>     }    
> }
> 
> 
> ### How JEP 445 works with JavaDoc today
> 
> In JDK 21, javadoc can document such a file **without any changes to the 
> javadoc tool**. The only thing that the user needs to do is to make sure that 
> the following options are present:
> 
> * `--enable-preview` and `--source=21`
> * `-package`
> 
> The first pair of options tells javadoc to use preview features, which JEP 
> 445 is one of. Without these preview-related options, javadoc will raise the 
> following error:
> 
> 
> % javadoc --version
> javadoc 21
> 
> % javadoc HelloWorld.java -d /tmp/throwaway
> Loading source file HelloWorld.java...
> HelloWorld.java:2: error: unnamed classes are a preview feature and are 
> disabled by default.
> void main() {
> ^
>   (use --enable-preview to enable unnamed classes)
> 1 error
> 
> 
> The second option, `-package`, tells javadoc to document classes that are 
> public, protected, or declared with package access (colloquially known as 
> "package private"). Without this option, javadoc will only document public 
> and protected classes, which do not include the interpreted class:
> 
> 
> % javadoc --enable-preview --source=21 HelloWorld.java -d /tmp/throwaway
> Loading source file HelloWorld.java...
> Constructing Javadoc information...
> error: No public or protected classes found to document.
> 1 error
> 
> 
> When those additional options are present, javadoc does its job:
> 
> 
> % javadoc --enable-preview --source=21 -package HelloWorld.java -d 
> /tmp/throwaway
> Loading source file HelloWorld.java...
> Constructing Javadoc information...
> Creating destination directory: "/tmp/throwaway/"
> Building index for all the packages and classes...
> Standard Doclet version 21+35-LTS-2513
> Building tree for all the packages and classes...
> Generating /tmp/throwaway/HelloWorld.htm...

Reviewers, please ignore changes to the following files as well as commits that 
brought them:

 * .github/workflows/main.yml
 * src/hotspot/share/utilities/nativeCallStack.cpp

Those changes seem to be transient artefacts of the workflow and should 
disappear on their own, eventually.

The reason those changes appeared in this PR is that this PR's branch is based 
on a more recent master than that of the PR that this PR depends on, 
https://github.com/openjdk/jdk/pull/16461.

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

PR Comment: https://git.openjdk.org/jdk/pull/16853#issuecomment-1829986363

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