GEP-16: val keyword for final declarations

[paulk-asert]

No description provided.

[Copilot]

Pull request overview

Adds support for the new Groovy keyword val (GEP-16) to represent final declarations, including lexer/parser support, AST modifier handling, editor highlighting, and coverage via new core/failure tests.

Changes:

• Extend ANTLR lexer/parser grammars to recognize val and allow it in the same contextual-identifier positions as similar keywords.
• Update AST modifier handling so val implies final, and add parse-time restrictions where val is invalid (e.g., type declarations, method return types).
• Add/adjust tests and fixtures for valid/invalid val usage and fix test code that used val as an identifier in ambiguous positions.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
subprojects/groovy-console/src/main/groovy/groovy/console/ui/text/SmartDocumentFilter.java	Adds VAL token to the console editor’s syntax-highlighting keyword list.
src/test/groovy/org/apache/groovy/parser/antlr4/SyntaxErrorTest.groovy	Adds failure tests for invalid val constructs.
src/test/groovy/org/apache/groovy/parser/antlr4/GroovyParserTest.groovy	Adds parser test coverage for a valid val usage script.
src/test/groovy/groovy/transform/stc/LambdaTest.groovy	Disambiguates a val field reference (this.val) to avoid conflicts with the new keyword.
src/test/groovy/bugs/Groovy5358.groovy	Renames a test property from val to stored to avoid keyword conflicts.
src/test-resources/fail/Val_01x.groovy	New fixture asserting val cannot be used for type declarations.
src/test-resources/fail/Val_02x.groovy	New fixture asserting val cannot be used for method return types/declarations.
src/test-resources/fail/Val_03x.groovy	New fixture asserting reassignment to a val variable fails.
src/test-resources/core/Val_01x.groovy	New fixture covering valid val usage patterns (including contextual keyword behavior).
src/main/java/org/codehaus/groovy/ast/ModifierNode.java	Maps VAL to ACC_FINAL and exposes isVal().
src/main/java/org/apache/groovy/parser/antlr4/AstBuilder.java	Adds val-related validation and updates modifier checks to include VAL.
src/antlr/GroovyParser.g4	Adds VAL to modifier/variableModifier/indexVariable/identifier/keywords rules.
src/antlr/GroovyLexer.g4	Introduces VAL : 'val'; token.

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[daniellansun]

+1