fix(frontend): materialize object upcasts for fixed call arguments - #83
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- Capture the builtin constructor rejection for an object subclass argument and the runtime receiver-lifetime behavior of method-reference sugar - Document the planned call-boundary upcast fix while preserving Godot semantics and backend exact matching
- Clarify the subclass-to-ancestor upcast exception for fixed call arguments - Document its boundary-temp naming and limit it to exact fixed-parameter routes - Mark the documentation-first step complete in the implementation plan
- Lower subclass arguments into parameter-typed temporaries for builtin, engine, and GDCC calls - Preserve exact-match backend constructor handling and verify upcast temporary ownership - Add lowering and codegen coverage for Callable, Signal, and regression boundaries - Complete implementation documentation and acceptance checklist
- Replace the completed implementation plan with a source-of-truth contract - Update documentation links and remove obsolete lowering guidance
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Copilot review overview
🟡 Changes recommended
Generated temporary allocation can collide with a user variable and overwrite its state.
Review effort: Lite
Findings: 1
What changed in this PR
Fixes frontend lowering by materializing strict object-subclass arguments into ancestor-typed temporaries for fixed call parameters.
Changes:
- Adds
AssignInsn-based upcast materialization. - Adds lowering, backend, and codegen tests.
- Documents conversion, ownership, and temporary naming contracts.
| File | Summary |
|---|---|
src/test/java/gd/script/gdcc/frontend/lowering/FrontendLoweringBodyInsnPassTest.java |
Tests lowering behavior and regression paths. |
src/test/java/gd/script/gdcc/backend/c/gen/CConstructInsnGenTest.java |
Tests constructor matching and ownership. |
src/test/java/gd/script/gdcc/backend/c/build/CallArgumentObjectUpcastCodegenTest.java |
Verifies generated C and ownership behavior. |
src/main/java/gd/script/gdcc/frontend/lowering/pass/body/FrontendBodyLoweringSession.java |
Implements fixed-call object upcast materialization. |
doc/module_impl/frontend/frontend_signal_support.md |
Documents Callable and Signal support anchors. |
doc/module_impl/frontend/frontend_rules.md |
Documents temporary naming rules. |
doc/module_impl/frontend/frontend_lowering_(un)pack_implementation.md |
Documents boundary materialization behavior. |
doc/module_impl/frontend/frontend_implicit_conversion_matrix.md |
Updates implicit conversion rules. |
doc/module_impl/frontend/frontend_call_argument_object_upcast_implementation.md |
Documents the implementation contract. |
doc/gdcc_ownership_lifecycle_spec.md |
Documents boundary temporary lifetime and ownership. |
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Comment on lines
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| var upcastSlotId = nextBoundaryMaterializationSlotId(boundaryUse, "upcast"); | ||
| ensureVariable(upcastSlotId, targetType); |
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Summary
Frontend lowering now materializes strict object subclass arguments passed to ancestor-typed fixed call parameters into target-typed temporaries via
AssignInsn, covering builtin constructors, engine methods, and GDCC calls. This un-rejects previously failing calls such asCallable(subclass_instance, &"method")while preserving backend exact-match constructor semantics.What changed
FrontendBodyLoweringSession): addedmaterializeCallArgumentBoundaryValuewith a strict-object-subclass peek (isStrictObjectSubclassArgument); only the fixed-parameter loop routes here, vararg tails andDYNAMIC_FALLBACKcalls are untouched.cfg_boundary_<use>_upcast_<n>and follow standard slot-write ownership with function-scoped__finally__cleanup.CallArgumentObjectUpcastCodegenTest(end-to-end codegen), plus lowering (FrontendLoweringBodyInsnPassTest) and C codegen (CConstructInsnGenTest) coverage for Callable/Signal constructor rejection anchors and upcast temp ownership.frontend_call_argument_object_upcast_implementation.mdsource-of-truth; updated ownership spec §3.6, implicit conversion matrix, (un)pack implementation §4.2/§4.3, frontend rules, and signal support anchors.Why
Callable(token, &"bump")with a customObjectsubclass).Affected packages/files
src/main/java/gd/script/gdcc/frontend/lowering/pass/body/FrontendBodyLoweringSession.javasrc/test/java/gd/script/gdcc/backend/c/build/CallArgumentObjectUpcastCodegenTest.java(new)src/test/java/gd/script/gdcc/backend/c/gen/CConstructInsnGenTest.javasrc/test/java/gd/script/gdcc/frontend/lowering/FrontendLoweringBodyInsnPassTest.javadoc/gdcc_ownership_lifecycle_spec.md,doc/module_impl/frontend/frontend_call_argument_object_upcast_implementation.md(new),frontend_implicit_conversion_matrix.md,frontend_lowering_(un)pack_implementation.md,frontend_rules.md,frontend_signal_support.mdValidation
script/run-gradle-targeted-tests.sh --tests CallArgumentObjectUpcastCodegenTest,CConstructInsnGenTest,FrontendLoweringBodyInsnPassTest(wraps
./gradlew test --tests ... --no-daemon --info --console=plain)Result:
BUILD SUCCESSFULRisks / Notes
cfg_tmp_*evaluation-temp behavior, so no Godot-observable divergence.DYNAMIC_FALLBACKroutes.Key behaviors covered (Optional)
AssignInsnfor builtin, engine, and GDCC call routes.ALLOW_DIRECT; unrelated object types keep the shared entry's rejection behavior.CConstructInsnGenTestasserts noown_object/try_own_object).Diff stats (Optional)
Breaking changes (Optional)
Related docs (Optional)
doc/module_impl/frontend/frontend_call_argument_object_upcast_implementation.mddoc/gdcc_ownership_lifecycle_spec.md§3.6doc/module_impl/frontend/frontend_lowering_(un)pack_implementation.md§4.2/§4.3