GROOVY-12035: Avoid emitting unreachable GOTO in if/else bytecode generation

[daniellansun]

https://issues.apache.org/jira/browse/GROOVY-12035

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.1958%. Comparing base (5318145) to head (797b022).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2556        +/-   ##
==================================================
+ Coverage     68.1844%   68.1958%   +0.0114%     
- Complexity      33086      33099        +13     
==================================================
  Files            1508       1508                
  Lines          126130     126147        +17     
  Branches        22878      22887         +9     
==================================================
+ Hits            86001      86027        +26     
+ Misses          32490      32486         -4     
+ Partials         7639       7634         -5     

Files with missing lines	Coverage Δ
.../codehaus/groovy/classgen/asm/StatementWriter.java	96.9310% <100.0000%> (+0.0079%)	⬆️

... and 8 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR addresses GROOVY-12035 by preventing StatementWriter.writeIfElse from emitting a GOTO that is guaranteed to be unreachable when the if block cannot fall through (e.g., it always returns or throws). This improves generated bytecode quality and avoids dead/unreachable instructions.

Changes:

• Guard the synthetic GOTO exitPath emission in if/else bytecode generation with maybeFallsThrough(ifBlock).
• Add a new regression test suite that compiles representative scripts and asserts the produced bytecode has no unreachable instructions (and that runtime behavior remains correct).

Reviewed changes

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

File	Description
src/main/java/org/codehaus/groovy/classgen/asm/StatementWriter.java	Avoids emitting an unreachable GOTO in if/else codegen when the if block can’t fall through.
src/test/groovy/org/codehaus/groovy/classgen/asm/IfElseBytecodeReachabilityTest.groovy	Adds regression tests to detect unreachable bytecode for dynamic/static if/else patterns with return/throw.

[testlens-app]

✅ All tests passed ✅

⚠️ TestLens detected flakiness ⚠️

Test Summary

Check	Project/Task	Test	Runs
Build and test / lts (17, ubuntu-latest)	:groovy-groovysh:test	HelpCommandTest > helpListsKnownCommands()	❌ ✅

🏷️ Commit: 797b022
▶️ Tests: 119732 executed
⚪️ Checks: 57/57 completed

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud