First cut grammar changes for Value Types (Value Classes and Objects) by mpalat · Pull Request #5088 · eclipse-jdt/eclipse.jdt.core

mpalat · 2026-05-29T10:42:18Z

What it does

Grammar changes for issue #4479.

First cut changes with a couple of tests.
Need to add more tests
Further refinement maybe required.

How to test

Use the junit tests providided at ValueClassesAndObjectsTest

Author checklist

I have thoroughly tested my changes
The change is following the coding conventions
I have signed the Eclipse Contributor Agreement (ECA)

stephan-herrmann

I couldn't hold my horses from browsing through these changes and dropping a few very superficial remarks here and there ...

mpalat · 2026-06-01T08:56:13Z

@stephan-herrmann - Thanks for the review comments - unfortunately I saw your comments after pushing another commit just now to the PR. I will address those review comments in a following commit soon.

stephan-herrmann

Some more comments :)

stephan-herrmann · 2026-06-13T13:08:57Z

Despite my nitpicky comments, I'd like to get a somewhat broader picture:

Is this PR ready for removal of "Draft" and building on jenkins?
If it's really only about grammar, what further steps do you plan before merging?
Should we first update the target branch from master?

Background: I made a first walk through of specification changes, and would like to start implementing individual new rules soonish.

PubScTest Failure fixes.

stephan-herrmann · 2026-06-18T09:39:46Z

No, intended to serve as common to many AbstractReTest. Yet to determine which all tests can derive from this.

So the purpose of this class remains unclear. Yet not a blocker for this PR.

mpalat · 2026-06-18T17:12:01Z

Despite my nitpicky comments, I'd like to get a somewhat broader picture:

Is this PR ready for removal of "Draft" and building on jenkins?

Yes, I 've moved it to Ready for Review

If it's really only about grammar, what further steps do you plan before merging?

The primary purpose was only about grammar. Some essential changes in other areas (like AST etc) was done, but grammar changes are the essentials. So, from that perspective, no further changes for this PR is envisaged.

Should we first update the target branch from master?

Yes, did that - VALCO_PDOT_1 was merged from master now.

Background: I made a first walk through of specification changes, and would like to start implementing individual new rules soonish.

sure. Am also going through the specs in more detail - quite a lot of small number of changes, I believe

Copilot

Pull request overview

This PR introduces first-cut Java 26 (preview) grammar and DOM updates for “Value Classes and Objects”, primarily by treating value as a restricted identifier/modifier and plumbing it through the scanner/parser/DOM layers.

Changes:

Add value as a restricted identifier token (scanner, terminal symbols, parser tables/grammar).
Expose value as a DOM modifier (Modifier.VALUE / VALUE_KEYWORD) and wire it into DOM conversion/rewrite utilities.
Add initial regression tests and a small shared preview-test base class.

Reviewed changes

Copilot reviewed 28 out of 48 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/PublicScanner.java	Map new `value` restricted-identifier token to public terminal symbols.
org.eclipse.jdt.core/model/org/eclipse/jdt/core/compiler/ITerminalSymbols.java	Add `TokenNameRestrictedIdentifiervalue` constant.
org.eclipse.jdt.core/dom/org/eclipse/jdt/internal/core/dom/util/DOMASTUtil.java	Gate DOM support for the new `VALUE` modifier based on JLS26+preview.
org.eclipse.jdt.core/dom/org/eclipse/jdt/internal/core/dom/rewrite/ASTRewriteAnalyzer.java	Preserve/emit `value` modifier during AST rewrite.
org.eclipse.jdt.core/dom/org/eclipse/jdt/core/dom/TypeBinding.java	Include `VALUE` in computed/valid type modifiers.
org.eclipse.jdt.core/dom/org/eclipse/jdt/core/dom/Modifier.java	Add `VALUE` modifier bit + keyword + helpers.
org.eclipse.jdt.core/dom/org/eclipse/jdt/core/dom/ASTConverter.java	Convert parser token `RestrictedIdentifiervalue` into DOM `Modifier.VALUE_KEYWORD`.
org.eclipse.jdt.core/dom/org/eclipse/jdt/core/dom/AST.java	Create `value` modifiers via `newModifiers(int flags)`.
org.eclipse.jdt.core/.settings/.api_filters	Add API filter entry for the new `VALUE_KEYWORD`.
org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/dom/ASTTest.java	Extend modifier-related DOM tests to cover `VALUE`.
org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/ValueClassesAndObjectsTest.java	New regression tests for restricted identifier + basic parsing scenario.
org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/TestAll.java	Hook (currently commented) test into the Java 26 suite bucket.
org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/ScannerTest.java	Extend restricted keyword token API test to include `value`.
org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericTypeTest.java	Update commented test selector line (non-functional).
org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/AbstractRegressionTestCommon.java	New base class to force preview enablement and align javac options.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/util/Messages.java	Add message key field for “value classes and objects”.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/problem/ProblemReporter.java	Add restricted-identifier normalization for `value`.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/TerminalToken.java	Add `TokenNameRestrictedIdentifiervalue` and mark it restricted.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/Scanner.java	Recognize `value` and disambiguate via lookahead/feature gating.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/ParserBasicInformation.java	Update generated parser constants (terminals/states/rules/etc.).
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/Parser.java	Update generated parser switch + consumeToken handling for `value`.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/AbstractCommentParser.java	Treat `value` as a token candidate during qualified-name parsing.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/messages.properties	Add “value_classes_and_objects” message text.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/TypeConstants.java	Add `VALUE_RESTRICTED_IDENTIFIER` constant.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/TypeBinding.java	Add default `isValue()` hook on compiler type bindings.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/ExtraCompilerModifiers.java	Add `AccValue` modifier bit.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/impl/JavaFeature.java	Add `VALUE_CLASSES_AND_OBJECTS` feature and restricted keyword metadata.
org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/classfmt/ClassFileConstants.java	Add `AccIdentity` constant alias.
org.eclipse.jdt.core.compiler.batch/grammar/java.g	Add terminal and modifier production for `RestrictedIdentifiervalue`.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

 *    <b>default</b>
 *    <b>sealed</b>
 *    <b>non-sealed</b>
+ *    <b>value<b>


+ * Community Process (JCP) and is made available for testing and evaluation purposes
+ * only. The code is not compatible with any specification of the JCP.
+ *
+ * * Contributors:


+	VALUE_CLASSES_AND_OBJECTS(ClassFileConstants.JDK26,
+			Messages.bind(Messages.primitives_in_patterns),
+			new char[][] {TypeConstants.VALUE_RESTRICTED_IDENTIFIER},
+			true),


 Modifier ::= Annotation
+Modifier -> RestrictedIdentifiervalue
 /.$putCase consumeAnnotationAsModifier(); $break ./


+    case 209 : if (DEBUG) { System.out.println("Modifier -> RestrictedIdentifiervalue"); }  //$NON-NLS-1$
 		    consumeAnnotationAsModifier(); 			break;


+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/


+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/


 			PrimitiveInPatternsTest.class,
 			PrimitiveInPatternsTestSH.class,
 			Unicode17Test.class,
+//			ValueClassesAndObjectsTest.class,


mpalat self-assigned this May 29, 2026

mpalat added the valtypes label May 29, 2026

stephan-herrmann reviewed May 31, 2026

View reviewed changes

mpalat marked this pull request as draft June 2, 2026 06:09

mpalat added this to the MilestoneNxt milestone Jun 2, 2026

stephan-herrmann reviewed Jun 13, 2026

View reviewed changes

mpalat added 4 commits June 18, 2026 09:58

First cut grammar changes for Value Types (Value Classes and Objects)

b45bfb4

Adding Value Modifier in JDT beyond batch, DOM AST additions and

c1dc3fe

PubScTest Failure fixes.

Addressing Review Comments

7d8681b

Further review comments addressed

0a861c4

mpalat force-pushed the valtypes_grammar_on_VALCO branch from ed0ada1 to 0a861c4 Compare June 18, 2026 04:28

Further Refactorings

9108e43

mpalat marked this pull request as ready for review June 18, 2026 17:05

mpalat requested a review from Copilot June 19, 2026 01:08

Copilot started reviewing on behalf of mpalat June 19, 2026 01:08 View session

Copilot AI reviewed Jun 19, 2026

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First cut grammar changes for Value Types (Value Classes and Objects)#5088

First cut grammar changes for Value Types (Value Classes and Objects)#5088
mpalat wants to merge 5 commits into
eclipse-jdt:VALCO_PDOT_1from
mpalat:valtypes_grammar_on_VALCO

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mpalat commented Jun 1, 2026 •

edited

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		case 209 : if (DEBUG) { System.out.println("Modifier -> RestrictedIdentifiervalue"); } //$NON-NLS-1$
		consumeAnnotationAsModifier(); break;

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mpalat commented May 29, 2026

What it does

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mpalat commented Jun 1, 2026 •

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