codegraph/docs/design/chained-call-resolution.md

Design + status: chained static-factory / fluent call resolution

Status: SHIPPED for 13 languages (C++, C, PHP, Java, Kotlin, C#, Swift, Rust, Go, Scala, Dart, Objective-C, Pascal/Delphi) + a conformance pass. TypeScript and Luau were evaluated and intentionally skipped (both gradually typed → the mechanism is +0 / regresses on real code). See "Full README classification" below. Tracking issue: #750 (which began as "the statically-typed README languages" but that enumeration was incomplete — it missed ObjC / Pascal / Luau).

Motivation: a call whose receiver is itself a call — a factory / singleton / builder that returns an object — should produce a calls edge to the chained method:

Foo.getInstance().bar();   // bar() should resolve to Foo::bar, never a same-named decoy

Before this work, every statically-typed language dropped the receiver and name-matched the bare method (bar), so in 7 of 9 languages it silently attached to a same-named method on an unrelated type — a correctness bug, not just missing coverage.

---

The 3-part mechanism (per language)

1. Capture the factory's declared return type — a per-language getReturnType hook writes nodes.return_type (schema v5). *Foo→Foo, List<Bar>→List, pkg.Foo→Foo, -> Self / : self / this.type → the declaring type.
2. Preserve the chained receiver at extraction — tree-sitter.ts (or a bespoke extractor) encodes Foo.getInstance().bar() as the marker string Foo.getInstance().bar (the (). marker never appears in an ordinary ref). A per-language gate keeps instance chains (list.map().filter()) bare so their existing resolution is untouched — only capitalized-receiver / factory chains re-encode.
3. Resolve AND VALIDATE — at resolution the receiver's type is inferred from what the inner call returns, then the outer method is resolved on that type and validated: the method must exist on the type (or a supertype it conforms to), so a wrong inference yields no edge, never a wrong one.

Three shared resolvers in src/resolution/name-matcher.ts, all calling resolveMethodOnType (which has the conformance supertype-walk):

Resolver	Receiver style	Languages
matchCppCallChain	field_expression (Foo::instance().bar)	C++, C
matchScopedCallChain	:: (Cls::for($x)->m, Foo::new().bar)	PHP, Rust
matchDottedCallChain	. (Foo.create().bar)	Java, Kotlin, C#, Swift, Go, Scala, Dart

Conformance pass (#754). When the chained method lives on a supertype the return type conforms to (an inherited / default-interface / trait / mixin / embedded method), the first pass can't see it — implements/extends edges aren't built yet. So failed chain refs are deferred (CHAIN_LANGUAGES in resolution/index.ts) and re-resolved in a second pass resolveChainedCallsViaConformance() after edges exist, walking context.getSupertypes(...).

Adding a language: getReturnType in languages/*.ts; encode the chained receiver

• a node-type gate; add the language to the right matchReference gate (and CONSTRUCTS_VIA_BARE_CALL if a bare capitalized call constructs the class); add to CHAIN_LANGUAGES; synthetic tests + a real-repo A/B; bump EXTRACTION_VERSION.

---

Coverage (validated — each via synthetic decoy/absent-method tests + a real-repo A/B)

Language	PR	Receiver	Real-repo A/B (unique calls edges)	Notes
C++ / C	#645 (#742)	field_expression	—	The original: singletons / factories / chained getters.
PHP	#608 (#749)	:: → ->	—	Cls::for($x)->method() — the Laravel per-tenant client idiom. : self/: static.
Java	#751	.	Guava +1,507 / −0	Missing-edge → purely additive.
Kotlin	#752	.	arrow +49 / −438	Wrong-edge → precision win (438 removed = test/doc noise + wrong). Needed the capitalized-receiver gate + constructor-receiver handling.
C#	#753	.	Newtonsoft +3 / NodaTime +73 / −0	Additive. Return type is the returns field; extension-method chains correctly don't resolve.
conformance	#754	(resolver upgrade)	arrow +22 / −0	Supertype walk — enables Swift protocol-ext, Rust trait, Go embedded, Dart mixin, Java/Kotlin/C# inherited chains.
Swift	#755	.	Alamofire / Kingfisher 0 / 0	Neutral-safe (unique fluent names already bare-resolved). Needed a nested-extension naming fix (KF.Builder→KF::Builder).
Rust	#757	::	clap +937 / −775	Precision win (622 wrong→right retargets, +162 net). -> Self; trait-default methods via conformance. Single-hop.
Go	#760	.	gin net-zero	New().Method(); embedded structs via conformance. Variable-inner fallback. Found + fixed a batched-resolver runaway (a mutated original.referenceName looped the offset-0 batch → 5M edges / 1.4 GB; fixed by tying the fallback to the original ref + a non-progress guard).
Scala	#761	.	gatling +14 / −59	Precision win (−59 = stdlib Option/Iterator .map/.flatMap the baseline mis-tied to gatling's Validation::*). Companion factories + case-class apply.
Dart	#762	.	localsend hand-written +17 / −10	Precision win + constructors made first-class (factory/named ctors Foo.create()/Foo._() are now indexed; unnamed Foo() stays instantiates). dartCtorInfo validates a ctor against the enclosing class name — handles a tree-sitter misparse where @override (A,B) m() makes m() look like a ctor.
Objective-C	#786	message send	SDWebImage +35 / −75	Precision win. Chained message send [[Foo create] doIt] over message_expression. getReturnType skips nullability qualifiers (nonnull instancetype). A class-message factory returns the receiver class by convention, so [[X alloc] init] / singleton chains resolve on X (validated). The −75 are wrong init mis-matches retargeted to the right class.
Pascal/Delphi	#791	. (exprDot)	PascalCoin +19 / −18	Precision win. TFoo.GetInstance().DoIt() over Pascal's exprCall/exprDot. getReturnType from the typeref (incl. interface returns IFoo). Re-encoding gated on the Delphi TFoo/IFoo type convention so capitalized variable chains stay bare. A constructor (no : TBar) or typecast TFoo(x) resolves on the class. 15 of the −18 are correct class→interface retargets (GetInstance(): IAsn1OctetString).
TypeScript	—	.	typeorm +0/−6 · nest +0/−164	Evaluated, NOT shipped — gradual typing; see below.
Luau	—	: / .	Fusion +0/−0 · matter +0/−0	Evaluated, NOT shipped — gradually typed; additive-safe (missing-edge gap, no regression) but real Luau rarely annotates factory returns, so +0 on both benchmarks. Works for Foo.create(): Bar then :doIt() (synthetic).

EXTRACTION_VERSION is now 16 (C++→…→Objective-C→Pascal). Re-index with codegraph index -f to pick up the newer extractor on an existing graph.

Why TypeScript was skipped

The mechanism resolves a chain from the factory's declared return type. TypeScript leans on type inference — e.g. NestJS's Test.createTestingModule(m) { return new TestingModuleBuilder(...) } has no : TestingModuleBuilder annotation — so the factory's type can't be recovered, the re-encoded chain can't resolve, and it drops the bare-name edge the existing resolver found. Real-repo A/B was +0 added on both typeorm and nest with a net recall regression (−164 on nest, mostly the ubiquitous Test.createTestingModule({…}).compile() pattern). The removed edges were mostly wrong (baseline mis-resolved .compile() to ModuleCompiler::compile), so it's precision-positive but recall-negative — against the recall-first invariant, and adding nothing where it doesn't hurt (TS method names are unique enough that bare-name already lands them). It was fully implemented (5 synthetic tests passed, runaway-safe bare-name fallback) and consciously not shipped. The only path to a TS win would be reading inferred return types (resolving return new X() in the factory body) — a much larger change. Full write-up on issue #750.

---

Full README classification (all 21 languages)

The mechanism's real requirement is a declared return type to recover the receiver's type — not "statically typed" (PHP qualifies via its : self / : Type return declarations). Against the README's full supported-language list:

Bucket	Languages
Covered (13)	C++, C, PHP, Java, Kotlin, C#, Swift, Rust, Go, Scala, Dart, Objective-C, Pascal/Delphi
Evaluated, skipped (2)	TypeScript — gradual typing → inference-typed factories can't be recovered; net recall regression. Luau — gradually typed; additive-safe but +0 on Fusion AND matter (real Luau rarely annotates factory returns). Both: the mechanism needs reliably-declared return types, which gradually-typed code too often omits.
Known limitation (not blocking)	Pascal/Delphi is shipped (#791), but only the paren'd chain TFoo.GetInstance().DoIt() is covered — the paren-less form TFoo.GetInstance.DoIt parses as a bare exprDot (not in callTypes) and isn't extracted as a call at all. Emitting paren-less method calls is a separate extractor follow-up (and a broader Pascal-coverage win independent of chains).
Out of scope — no declared return types (6)	JavaScript, Ruby, Lua, Svelte, Vue, Liquid (Liquid has no methods/chains at all)
Partial / separate (1)	Python — only optional -> T hints; tracked as #578, not part of this mechanism

So #750's original framing ("the 9 statically-typed README languages") was incomplete — it missed three more typed languages, all now resolved: Objective-C shipped (#786, same wrong-edge gap, mechanism ports directly); Pascal/Delphi shipped (#791, a clean port for the paren'd chain — an initial "blocked" read was wrong, caused by probing only the paren-less form); Luau evaluated and skipped (gradual typing → +0 on real repos, additive-safe).

The through-line: this mechanism fits languages with reliably-declared return types (the 13 shipped). Gradually-typed languages (TypeScript, Luau) omit them too often for it to pay off, and dynamically-typed languages have none.

---

Edge cases / model

• Single-hop: a chain re-encodes one hop; deeper hops (a.b().c().d()) keep the bare name (the inner () defeats the Class::method split). Re-measure on deep fluent-builder repos.
• Validation, not guessing: every resolver ends in resolveMethodOnType, so an unknown / wrong inferred type produces no edge — the decoy / absent-method guarantee that makes this safe to ship.
• Per-language receiver gate keeps instance chains bare so existing resolution is never regressed; the A/B "removed" counts are wrong-edge corrections, not losses.

Related work

• Dynamic-dispatch / callback synthesis (a different mechanism): observer / EventEmitter / React-render / JSX-child / django-ORM edge synthesis lives in callback-edge-synthesis.md + dynamic-dispatch-coverage-playbook.md.
• The verbose session working-notes for #750 are in .claude/handoffs/chained-call-multilang-probe.md (scratch; this doc is the permanent record).