RFR: 8306914: Implementation of JEP Launch Multi-File Source-Code Programs

[Joe Darcy]

On Fri, 28 Apr 2023 08:00:36 GMT, Christian Stein <cstein at openjdk.org> wrote:

> Please review this change set implementing [JEP 458](https://openjdk.org/jeps/458) "Launch Multi-File Source-Code Programs" by introducing a new entry-point `SourceLauncher` in package `com.sun.tools.javac.launcher` of module `jdk.compiler`. The former `Main` entry-point is kept as-is in order to preserve (and possibly fall back to) existing behaviour of launching single-file source-code programs.
> 
> The code of the new entry-point and other new classes introduced by this pull request is based on the original implementation. It extends it to dynamically resolve required types "on-the-fly" using an in-memory class loader capable to compile Java source files - applying a strict name-based pattern as described in the JEP.
> 
> To support modular programs with user-provided additional modules (launched for example via `java -p . pkg/Prog1.java`) `ALL-MODULE-PATH` is now also part of the implicit list of modules name in source launch mode.
> 
> ### Open Ends
> 
> - [ ] Tests with [JEP ?: Implicitly Declared Classes and Instance Main Method (2nd Preview)](https://bugs.openjdk.org/browse/JDK-8315398)
> 
> ### OpenJDK's Demo Programs
> 
> OpenJDK's demo programs can be found in the [src/demo/share/jfc](https://github.com/openjdk/jdk/tree/master/src/demo/share/jfc) directory. These multi-file source-code programs can be launched via `java ${PROGRAM}` once this implementation is integrated; with `${PROGRAM}` being one of the following files:
> 
> - [x] `src/demo/share/jfc/CodePointIM/CodePointIM.java`
> - [x] `src/demo/share/jfc/FileChooserDemo/FileChooserDemo.java`
> - [x] `src/demo/share/jfc/Font2DTest/Font2DTest.java`
> - [x] `src/demo/share/jfc/J2Ddemo/java2d/J2Ddemo.java`
> - [x] `src/demo/share/jfc/Metalworks/Metalworks.java`
> - [x] `src/demo/share/jfc/Notepad/Notepad.java`
> - [x] `src/demo/share/jfc/SampleTree/SampleTree.java`
> - [ ] `src/demo/share/jfc/Stylepad/Stylepad.java` — requires `src/demo/share/jfc/Notepad/Notepad.java`
> - [x] `src/demo/share/jfc/SwingSet2/SwingSet2.java`
> - [ ] `src/demo/share/jfc/TableExample/TableExample.java` — requires a database driver on the class path
> - [ ] `src/demo/share/jfc/TableExample/TableExample2.java` —  requires a database driver on the class path
> - [x] `src/demo/share/jfc/TableExample/TableExample3.java`
> - [x] `src/demo/share/jfc/TableExample/TableExample4.java`
> - [x] `src/demo/share/jfc/TransparentRuler/transparentruler/Ruler.java`

A few high-level comments after an initial read over the PR:

I recommend declared the new top-level cases final (or sealed) where possible.

I suggest leaving some "breadcrumbs" in other option-handling locations in the code base to provide maintenance reminders that if a "relevant" option is added, it should be added to the RelevantJavacOptions list.

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PR Comment: https://git.openjdk.org/jdk/pull/13712#issuecomment-1548925681