GROOVY-11022: StackOverflowError when having parameterized function w…

[paulk-asert]

…ith recursive bounds

This is the fix recommended for GROOVY_5_0_X

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 67.1396%. Comparing base (5a41b8f) to head (fad65c6).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
...roovy/transform/stc/StaticTypeCheckingSupport.java	90.9091%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2496        +/-   ##
==================================================
+ Coverage     67.1374%   67.1396%   +0.0021%     
- Complexity      31622      31627         +5     
==================================================
  Files            1451       1451                
  Lines          122565     122573         +8     
  Branches        22007      22009         +2     
==================================================
+ Hits            82287      82295         +8     
+ Misses          33199      33197         -2     
- Partials         7079       7081         +2     

Files with missing lines	Coverage Δ
...roovy/transform/stc/StaticTypeCheckingSupport.java	81.5790% <90.9091%> (+0.0419%)	⬆️

... and 6 files with indirect coverage changes

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[Copilot]

Pull request overview

Fixes GROOVY-11022 (StackOverflowError during static type checking) by adding a recursion guard when expanding generic placeholder bounds, and adds a regression test covering F-bounded type parameters with self-references inside wildcard bounds.

Changes:

• Add a per-thread “currently expanding bounds” stack to prevent infinite recursion in applyGenericsContext for F-bounded generics with wildcard self-references.
• Add STC regression tests for ? super / ? extends self-referential bounds patterns.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/test/groovy/groovy/transform/stc/GenericsSTCTest.groovy	Adds regression coverage for the StackOverflowError scenario involving recursive bounds inside wildcards.
src/main/java/org/codehaus/groovy/transform/stc/StaticTypeCheckingSupport.java	Introduces a recursion guard during generics bound expansion to avoid infinite recursion.

[blackdrag]

I am very critical to using a ThreadLocal. At the very least there should be a description of why this has to be ThreadLocal

[blackdrag]

so we push to expanding and then pop from expanding. That means we remove the entry we just added, even in the case of line 1806, with the return. Why is it then not always empty again? Ah, because of the recursive call applyGenericsContext(spec, gt.getLowerBound()). But why does it have to be a ThreadLocal then? I would prefere going for a breaking change here nstead of using ThreadLocal

[paulk-asert]

Abandoned, instead the slightly larger solution for master will be back-ported.