GROOVY-11983: STC: unsound smart-cast in else branch of if (cond && !…

[paulk-asert]

…(x instanceof Y))

[Copilot]

Pull request overview

This PR addresses GROOVY-11983 by preventing Static Type Checking (STC) from performing an unsound smart-cast in the else/false branch when the condition uses && together with !instanceof, which could otherwise lead to an erroneous checkcast and runtime ClassCastException.

Changes:

• Added regression tests covering if/else, ternary, and early-return forms for cond && !instanceof.
• Updated STC’s else/false-branch narrowing inversion to be conditional (guarded by a new predicate).
• Introduced canInvertNarrowingForElseBranch to decide when it is safe to invert temporary type info.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/test/groovy/groovy/transform/stc/TypeInferenceSTCTest.groovy	Adds GROOVY-11983 regression coverage for && + !instanceof not producing a positive smart-cast in else/false paths.
src/main/java/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java	Makes else/false-branch inversion of temporary instanceof tracking conditional via canInvertNarrowingForElseBranch.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 75.00000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.3303%. Comparing base (88ca738) to head (7a6c967).

Files with missing lines	Patch %	Lines
...roovy/transform/stc/StaticTypeCheckingVisitor.java	75.0000%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2509        +/-   ##
==================================================
+ Coverage     67.3235%   67.3303%   +0.0068%     
- Complexity      32253      32272        +19     
==================================================
  Files            1490       1490                
  Lines          125044     125061        +17     
  Branches        22505      22518        +13     
==================================================
+ Hits            84184      84204        +20     
+ Misses          33535      33532         -3     
  Partials         7325       7325                

Files with missing lines	Coverage Δ
...roovy/transform/stc/StaticTypeCheckingVisitor.java	87.4253% <75.0000%> (-0.0747%)	⬇️

... and 5 files with indirect coverage changes

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