super: walk up inheritance chain past empty intermediates

[borisbat]

Summary

Fixes three related gaps in the super machinery when an intermediate class/struct defines no constructor, no method, or no finalizer.

• super() constructor. Was crashing with SIGSEGV on super(arg) because the rewrite ran in InferTypes::preVisit(ExprCall*), where arg->type is still nullptr and findMatchingFunctions segfaults on null type lookups. Moved the rewrite to visit (post-visit), where children are typed. Also added the walk-up loop and "no matching super constructor" / "too many candidates" diagnostics for parity with super.method().
• super.method(). Already had walk-up logic in visit(ExprCall*); left untouched, now exercised by new tests.
• delete super.self. Was always casting to the immediate parent, so a chain like class C : B {} / class B : A { def operator delete } silently dropped A's finalizer when invoked from C. Now walks selfStruct->parent->parent… and stops at the nearest ancestor whose type resolves a user-defined finalize, filtering out auto-generated generateStructureFinalizer / makeClassFinalize via Function::generated (those don't chain).

The walk-up matches by argument types, so overloaded super(args) calls and super.method(args) overrides still pick the correct ancestor.

What changed

• src/ast/ast_infer_type.cpp — moved super constructor rewrite from preVisit to post-visit; added walk-up + diagnostics for delete super.self.
• tests/language/super.das — 4 new skip-level tests (default ctor, ctor with args, method, method with args).
• tests/language/super_finalize.das — 4 new tests: 1-empty intermediate class, 2-empty deep class, mid-chain (only some ancestors define finalizers), struct skip-level.
• doc/source/reference/language/classes.rst — added a "walks up the inheritance chain to the nearest ancestor that does" subsection with a worked Base/Mid/Leaf example; updated the delete super.self rewrite description from cast<Base> to cast<Ancestor>.
• doc/source/reference/language/structs.rst — same one-line correction for delete super.self.

Test plan

• tests/language/super.das — 12/12 pass under interpreter and AOT (was 8 before; 4 new skip-level cases)
• tests/language/super_finalize.das — 8/8 pass under interpreter and AOT (was 4 before; 4 new skip-level cases)
• Full tests/language/ — 925/925 pass under interpreter (was 917 before adding the 8 new cases)
• Full tests/language/ under AOT (test_aot -use-aot) — 925/925 pass
• tests/language/cant_delete_super_self.das (negative test) — still produces the same expected compile errors
• Sphinx build clean (no warnings) on the two updated RST files
• examples/wip.das (the original repro) compiles and runs

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes several inheritance “skip-level” edge cases in daScript’s super lowering by making super()/super.method()/delete super.self resolve past empty intermediate classes/structs, and adds tests + documentation updates to lock in the intended behavior.

Changes:

• Move super(args) constructor rewriting to post-visit type inference and add ancestor walk-up + improved diagnostics.
• Update delete super.self lowering to search up the inheritance chain for the nearest ancestor finalizer (skipping empty intermediates).
• Add language tests for skip-level inheritance cases and update the reference docs accordingly.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/ast/ast_infer_type.cpp	Adjusts inference-time rewrites for super() constructors, super calls, and delete super.self to walk up inheritance chains and improve diagnostics.
tests/language/super.das	Adds tests covering skip-level constructor and method resolution through an empty intermediate class.
tests/language/super_finalize.das	Adds tests ensuring delete super.self chains correctly past empty intermediates for both classes and structs.
doc/source/reference/language/classes.rst	Documents super walk-up behavior and updates delete super.self rewrite description.
doc/source/reference/language/structs.rst	Updates delete super.self rewrite description for structs.

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[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.