GROOVY-12117: replace super trait search with more complete helper stub

[eric-milles]

In order to support some code assist or type inferencing for traits, I needed to fill out the trait helper stub a little more. This solution also works for GROOVY-12117 instead of the super trait method search. That is why I could not get the 12117 test case to trip locally.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.50.

Benchmark suite	Current: 5f40130	Previous: aa30a69	Ratio
org.apache.groovy.bench.AryBench.java ( {"n":"10"} )	0.006551610504040221 ms/op	0.004037354064242993 ms/op	1.62

This comment was automatically generated by workflow using github-action-benchmark.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 88.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.6961%. Comparing base (523fd1e) to head (5f40130).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...va/org/codehaus/groovy/transform/trait/Traits.java	88.0000%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2678        +/-   ##
==================================================
- Coverage     68.6980%   68.6961%   -0.0019%     
+ Complexity      34121      34118         -3     
==================================================
  Files            1536       1536                
  Lines          128912     128933        +21     
  Branches        23368      23375         +7     
==================================================
+ Hits            88560      88572        +12     
- Misses          32522      32527         +5     
- Partials         7830       7834         +4     

Files with missing lines	Coverage Δ
...oovy/transform/trait/TraitReceiverTransformer.java	88.8325% <ø> (+0.2753%)	⬆️
...va/org/codehaus/groovy/transform/trait/Traits.java	86.5772% <88.0000%> (-0.3459%)	⬇️

... and 8 files with indirect coverage changes

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[github-actions]

JMH summary — classic (commit bea529e)

Speedup vs trailing 90-day baseline on gh-pages. Higher = faster.
1.00 = in line with history. Per-benchmark ratio, geomean within group.
Time-per-op units inverted so direction is consistent. The calibrated
column divides out this runner's speed vs the baseline hardware, as
measured by Groovy-independent pure-Java ruler benchmarks.

Group	Speedup	Calibrated	n
bench	1.037 ×	0.996 ×	78
core	1.024 ×	1.065 ×	77
grails	0.983 ×	1.034 ×	80

_{Runner calibration (this run vs baseline hardware): bench 1.04× (26 rulers) · core-ag 0.92× (3 rulers) · core-hz 1.01× (3 rulers) · grails-ad 0.91× (3 rulers) · grails-ez 0.98× (3 rulers)}

_{Baseline: dev/bench/jmh/<part>/classic/data.js on gh-pages, trailing 90 days. Daily dashboard · Per-suite raw data}

[github-actions]

JMH summary — indy (commit bea529e)

Speedup vs trailing 90-day baseline on gh-pages. Higher = faster.
1.00 = in line with history. Per-benchmark ratio, geomean within group.
Time-per-op units inverted so direction is consistent. The calibrated
column divides out this runner's speed vs the baseline hardware, as
measured by Groovy-independent pure-Java ruler benchmarks.

Group	Speedup	Calibrated	n
bench	0.979 ×	1.002 ×	78
core	3.666 ×	3.525 ×	77
grails	2.177 ×	2.058 ×	80

_{Runner calibration (this run vs baseline hardware): bench 0.98× (26 rulers) · core-ag 1.07× (3 rulers) · core-hz 1.00× (3 rulers) · grails-ad 1.06× (3 rulers) · grails-ez 1.06× (3 rulers)}

_{Baseline: dev/bench/jmh/<part>/indy/data.js on gh-pages, trailing 90 days. Daily dashboard · Per-suite raw data}

[paulk-asert]

AI said the PR broke ordering, so I added an existing test to show that - and the PR breaks now - but the fix should be easy.

AI read below:

---

Thanks for this — replacing the super-trait search with a fuller helper stub is a nice simplification, and modelling the not-yet-lowered helper as a real stub (rather than the empty GROOVY-7909 one) is the right direction for the code-assist/inferencing goal. It also happens to fix a latent bug the old empty stub had: in SuperCallTraitTransformer, isStatic is derived from the helper's methods, so T.super.staticMethod() in the not-yet-lowered window previously received this instead of this.class; a populated stub makes that window behave like the lowered case.

One behavioural concern before this lands, though: as written, the stub drops the original method's annotations, which makes @Virtual static dispatch depend on trait transform order — exactly the order-independence this PR's own javadoc says it preserves.

Why

HelperClassStub.helperMethod adds only @Implemented, whereas the real helper method (TraitASTTransformation.processMethod) copies all of the original method's annotations, including @Virtual. TraitReceiverTransformer.findConcreteMethod's result is then branched on by hasAnnotation(methodNode, VIRTUAL_TYPE) to choose dynamic dispatch vs. declarer-bound dispatch. So for this.m(x) where m is a @Virtual public static on a super trait:

• super trait already lowered → real helper method carries @Virtual → dynamic-dispatch path ✔
• super trait not yet lowered (stub window) → stub method lacks @Virtual → declarer-bound path ✘

The removed getDeclaredMethods fallback returned the original MethodNode with @Virtual intact, so it was order-independent here. The failure is silent — the implementer's static override just stops being visible from trait code depending on sibling-trait declaration order.

Reproducer

This is the sub-trait-first counterpart of the existing Groovy11985.testSuperTraitPublicStaticIsPolymorphic:

@Test
void testSuperTraitPublicStaticIsPolymorphicSubTraitFirst() {
    GroovyAssert.assertScript '''
        import groovy.transform.Virtual
        trait Mid extends Base { static String greet() { hello() } }   // sub-trait declared FIRST
        trait Base { @Virtual static String hello() { 'base' } }
        class C implements Mid {}
        class D implements Mid { static String hello() { 'override' } }
        assert C.greet() == 'base'
        assert D.greet() == 'override'
    '''
}

• Passes on the current baseline (the merged GROOVY-12117: Resolution of inherited static trait method from sub-tr… #2644 fallback returns the original method with @Virtual): https://github.com/apache/groovy/actions/runs/28987961170/job/86021221878
• Fails when this PR is applied (rebased to include the test) — D.greet() returns 'base' instead of 'override': https://github.com/apache/groovy/actions/runs/28988500410

Suggested fix

Copy the original method's annotations onto the stub method, mirroring processMethod (which excludes @Override). No new imports needed — AnnotationNode and ClassHelper are already imported in Traits.java.

             var m = new MethodNode(method.getName(), mods, method.getReturnType(), helperParams, method.getExceptions(), null);
-            m.addAnnotation(Traits.IMPLEMENTED_CLASSNODE);
+            // Mirror processMethod's annotation copy: findConcreteMethod dispatches on
+            // @Virtual, so a stub method missing it silently picks declarer-bound dispatch.
+            for (AnnotationNode annotation : method.getAnnotations()) {
+                if (!annotation.getClassNode().equals(ClassHelper.OVERRIDE_TYPE)) {
+                    m.addAnnotation(annotation);
+                }
+            }
             m.setGenericsTypes(method.getGenericsTypes());

(Dropping the explicit @Implemented is intentional: the real helper methods don't carry it either — processMethod adds @Implemented to the original interface method, not to the helper copy.)

With this change the full trait suite still passes (TraitASTTransformationTest, TraitStaticDispatchMatrix, TraitGenericsMatrix, VirtualAnnotationTest, Groovy11985/12104/12105/12106/12112), and the reproducer above goes green.

Optional fidelity tweaks (not required to fix the bug)

Since the stub now feeds code-assist/inferencing, a couple of small alignments with processMethod/createSelfParameter would make stub signatures match the lowered ones:

• self parameter: use trait.getPlainNodeReference() and the names $self / $static$self (Traits.THIS_OBJECT / Traits.STATIC_THIS_OBJECT) instead of the raw generic node and "traitImplementer" — avoids leaking unbound placeholders into Class<T<X>>;
• add ACC_FINAL for final instance methods, as processMethod does.

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
86.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[testlens-app]

✅ All tests passed ✅

🏷️ Commit: 5f40130
▶️ Tests: 87054 executed
⚪️ Checks: 31/31 completed

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