8309235: Unnamed Variables (_) can't be used in JShell

[biboudis]

This PR addresses the issue of JShell not accepting unnamed local variables. This solution prints all local variables via the /vars command. e.g.,

jshell> int _ = 42;
 ==> 42

jshell> int _ = 43;
 ==> 43

jshell> String _ = "44";
 ==> "44"

jshell> /vars
|    int _ = 42
|    int _ = 43
|    String _ = "44"

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8309235: Unnamed Variables (_) can't be used in JShell (Bug - P4)

Reviewers

• Adam Sotona (@asotona - Reviewer) ⚠️ Review applies to 953b5846

Contributors

• Jan Lahoda <jlahoda@openjdk.org>
• Aggelos Biboudis <abimpoudis@openjdk.org>

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/14337/head:pull/14337
$ git checkout pull/14337

Update a local copy of the PR:
$ git checkout pull/14337
$ git pull https://git.openjdk.org/jdk.git pull/14337/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 14337

View PR using the GUI difftool:
$ git pr show -t 14337

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/14337.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back abimpoudis! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[biboudis]

/contributor add @lahodaj

[openjdk]

@biboudis The following label will be automatically applied to this pull request:

• kulla

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[openjdk]

@biboudis
Contributor Jan Lahoda <jlahoda@openjdk.org> successfully added.

[biboudis]

/contributor add @biboudis

[openjdk]

@biboudis
Contributor Aggelos Biboudis <abimpoudis@openjdk.org> successfully added.

[mlbridge]

Webrevs

• 02: Full - Incremental (970a7635)
• 01: Full - Incremental (953b5846)
• 00: Full (2e44300a)

[asotona]

Looks good 👍

[openjdk]

@biboudis This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8309235: Unnamed Variables (_) can't be used in JShell

Co-authored-by: Jan Lahoda <jlahoda@openjdk.org>
Co-authored-by: Aggelos Biboudis <abimpoudis@openjdk.org>
Reviewed-by: asotona

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 74 new commits pushed to the master branch:

• 9d64a9d: 8306431: File.listRoots method description should be re-examined
• 5af9d2a: 8309602: update JVMTI history table for jdk 21
• 6646272: 8308764: Reporting errors from create_vm may crash
• 73dd03c: 8308152: PropertyDescriptor should work with overridden generic getter method
• 760cb04: 8309569: sun/security/pkcs11/Signature/TestRSAKeyLength.java fails after JDK-8301553
• e8a5984: 8309630: Clean up tests that reference deploy modules
• 90027ff: 8309515: Stale cached data from Matcher.namedGroups() after Matcher.usePattern()
• ea41907: 8297923: java.awt.ScrollPane broken after multiple scroll up/down
• 99749c5: 8309562: [JVMCI] Export symbols used by VirtualThread notifyJvmti intrinsics to JVMCI compilers.
• 92beb85: 8309474: [IR Framework] Wrong @ForceCompile link in README
• ... and 64 more: https://git.openjdk.org/jdk/compare/6d511f1376e3a0183a484443d05142678bdaa1c2...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@asotona) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[biboudis]

/integrate

[openjdk]

@biboudis
Your change (at version 970a763) is now ready to be sponsored by a Committer.

[asotona]

/sponsor

[openjdk]

Going to push as commit 79a4ac7.
Since your change was applied there have been 74 commits pushed to the master branch:

• 9d64a9d: 8306431: File.listRoots method description should be re-examined
• 5af9d2a: 8309602: update JVMTI history table for jdk 21
• 6646272: 8308764: Reporting errors from create_vm may crash
• 73dd03c: 8308152: PropertyDescriptor should work with overridden generic getter method
• 760cb04: 8309569: sun/security/pkcs11/Signature/TestRSAKeyLength.java fails after JDK-8301553
• e8a5984: 8309630: Clean up tests that reference deploy modules
• 90027ff: 8309515: Stale cached data from Matcher.namedGroups() after Matcher.usePattern()
• ea41907: 8297923: java.awt.ScrollPane broken after multiple scroll up/down
• 99749c5: 8309562: [JVMCI] Export symbols used by VirtualThread notifyJvmti intrinsics to JVMCI compilers.
• 92beb85: 8309474: [IR Framework] Wrong @ForceCompile link in README
• ... and 64 more: https://git.openjdk.org/jdk/compare/6d511f1376e3a0183a484443d05142678bdaa1c2...master

Your commit was automatically rebased without conflicts.

[openjdk]

@asotona @biboudis Pushed as commit 79a4ac7.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.