GROOVY-12099: Elvis-assignment on array element evaluates receiver an…

[paulk-asert]

…d index twice

[Copilot]

Pull request overview

Fixes GROOVY-12099 by ensuring Elvis-assignment with a subscript LHS (e.g. a[i] ?= b) evaluates the receiver and index exactly once (left-to-right), reusing them for both the getAt read and putAt write during bytecode generation.

Changes:

• Add regression tests covering dynamic and @CompileStatic cases for arrays and lists, including receiver/index side-effect ordering.
• Update BinaryExpressionHelper.evaluateElvisEqual to cache subscript receiver/index into temporaries for non-safe subscripts and reuse them for read/write.
• Introduce a small helper to evaluate-and-store an expression in a temporary slot while preserving type information for subsequent resolution.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/test/groovy/bugs/Groovy12099.groovy	Adds focused regression coverage for single-evaluation and correct semantics across falsy/truthy, side effects, arrays/lists, and @CompileStatic.
src/main/java/org/codehaus/groovy/classgen/asm/BinaryExpressionHelper.java	Adjusts Elvis-assignment bytecode rewrite for subscript LHS to avoid duplicate receiver/index evaluation by storing them into temporaries and reusing loaders.

[testlens-app]

✅ All tests passed ✅

⚠️ TestLens detected flakiness ⚠️

Test Summary

Build and test / lts (17, windows-latest, 1) > :test

Test	Runs
GenericsSTCTest > testReturnTypeInferenceWithMethodGenerics18()	❌ ✅
GenericsSTCTest > testReturnTypeInferenceWithMethodGenerics18a()	❌ ✅
GenericsStaticCompileTest > testReturnTypeInferenceWithMethodGenerics18()	❌ ✅
GenericsStaticCompileTest > testReturnTypeInferenceWithMethodGenerics18a()	❌ ✅

Build and test / lts (25, ubuntu-latest) > :test

Test	Runs
StreamClassloaderInScriptTest > testSerializationToFileWithinScript	❌ ✅

🏷️ Commit: 0f55195
▶️ Tests: 40609 executed
⚪️ Checks: 30/30 completed

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.50000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.4541%. Comparing base (40c6203) to head (0f55195).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
...us/groovy/classgen/asm/BinaryExpressionHelper.java	87.5000%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2622        +/-   ##
==================================================
- Coverage     68.4541%   68.4541%   -0.0001%     
- Complexity      33505      33512         +7     
==================================================
  Files            1518       1518                
  Lines          127107     127129        +22     
  Branches        23065      23067         +2     
==================================================
+ Hits            87010      87025        +15     
- Misses          32371      32377         +6     
- Partials         7726       7727         +1     

Files with missing lines	Coverage Δ
...us/groovy/classgen/asm/BinaryExpressionHelper.java	88.7346% <87.5000%> (-0.0833%)	⬇️

... and 9 files with indirect coverage changes

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