Carry minted type identity through interface dispatch - #4516
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No actionable comments were generated in the recent review. 🎉 ℹ️ Recent review info⚙️ Run configurationConfiguration used: Repository UI Review profile: CHILL Plan: Pro Plus Run ID: 📒 Files selected for processing (4)
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Included review availability: Your plan provides up to 8 included reviews per hour; 5 remain after this review. 📝 WalkthroughWalkthroughThe VM reconstructs runtime class and enum identities and propagates them through interface dispatch. Package object conversion uses these identities. Tests cover dispatch paths, identity boundaries, generic bindings, enums, and package declarations. ChangesRuntime type identity preservation
Estimated code review effort: 4 (Complex) | ~45 minutes Merge Risk: ⚪ Minimal · up to The PR carries minted type identity through interface dispatch with focused regression coverage; no actionable merge-blocking risk remains beyond normal checks and review. Sequence Diagram(s)sequenceDiagram
participant Caller
participant VirtualDispatch
participant BexVm
participant CalleeFrame
Caller->>VirtualDispatch: invoke interface or inherited default method
VirtualDispatch->>BexVm: recover owner TypeValue values
BexVm-->>VirtualDispatch: return runtime identities
VirtualDispatch->>CalleeFrame: pass owner and method type values
CalleeFrame-->>Caller: preserve identity for comparison and lookup
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I am eliminating minted types in favor of a more stable representation that should eliminate the problem altogether. It should cover this case as well. |
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Review round applied. The blocking finding was correct and I reproduced both regressions before fixing them. The blocking fix
Recovery is now gated on Verified independently by removing the gate and re-running the new regressions:
The first is a regression against canary (which was right by never recovering at all); the second is Consequences handled
Focused suite: |
The resolver realizes an impl frame off the receiver's `Self`, which carries realized types only, so `type.of<T>()` inside an implements-block or inherited default method derived a fresh mint for a type the caller had already minted. The value named the same definition and rendered and parsed identically, but it was `==`-distinct, so every identity-keyed pattern silently missed. The interface operand already carries the definitions those slots name (#4501), and a runtime definition records the mint it was created with, so the exact value is read back off the definition rather than re-derived and handed to the callee frame in `FrameTypeMetadata.values` alongside any method-level slots. `type.of_value` performed the same reconstruction inline; both now share one `runtime_declaration_identity`. A static interface operand carries no definitions and skips the recovery entirely, so the non-reflective dispatch path is byte-for-byte the same.
Review found the recovery unsound for any name several definitions can spell. `DynTypeDefs` is keyed by `QualifiedTypeName`, and only a `runtime_local` name carries its mint in the name; a static declaration and a compiled package's declaration are both plain `user.Foo`. `LoadType` staples the whole frame overlay onto anything materialized in that frame, so a by-name lookup answered from a *different* definition. Two shapes, both now regressions and both verified failing without the gate: a static `Holder<Item>` in a frame that also bound a compiled package's `Item` reported `type.of<T>() != type.of<Item>()` and `==` the package's mint (a regression against canary, which never recovered at all); and two compiled packages each declaring `Item` cross-matched, so `Holder<B>` answered `true` against A. Returning a wrong identity is worse than returning none, so everything but a mint-unique name declines and re-derives normally. That makes compiled-package declarations a documented gap rather than a covered case; the test that claimed them is flipped to the contract that is actually true — definitions still travel, identity does not — and the claim moves to the PR body next to the derived-types gap. Also promotes the owner+method slot alignment and the runtime-enum slot from unit tests to end-to-end oracles, and records the pre-existing #4501-era unrooted window between the restored pending values and the frame write.
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In `@baml_language/crates/bex_vm/src/vm.rs`:
- Around line 7741-7770: Update MakeVirtualBoundMethod and the BoundMethod
representation to preserve exact owner TypeValue values and DynTypeDefs from the
interface operand, rather than retaining only realized type_args. Ensure
CallIndirect installs these values and definitions into the callee
FrameTypeMetadata so bound interface calls retain the receiver’s runtime owner
mint. Add a regression comparing type.of<T>() between direct and bound
interface-method calls.
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Gate for the review round (toolchain 1.93.0, The one failure is environmental, not this change: inside it, 3113 of 3114 stdlib cases pass and the single failing case is a local media fetch timing out — Re-run alone on an idle machine: 3114 passed, 0 failed. (The box was running two agents' gates; the same test also hit the nextest slow-timeout in earlier runs. Nothing in this PR touches media fetching.) Also green: |
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Review follow-ups on the mint-key change: - The four-surface render pin joined with `|` and split on it, but `to_baml()` and the LLM schema both spell a union with `|`, so the split could land inside a surface and leave the per-surface assertions silently comparing the wrong text. Joins and splits on `~~` now. - The changelog entry says outright that it supersedes the compiled-package exclusion the #4516 entry below it still describes. - Two tests pin the collision-freedom claim behind `$dyn`. `$dyn` does lex as a word, but the marker is only ever read as a *namespace* segment, and the only thing that puts one there for user code is an `ns_<name>` folder whose suffix must start with a letter or `_` and hold only alphanumerics and `_` — so `ns_$dyn` and `ns_0` are dropped rather than becoming namespaces, and neither half of `user.$dyn.<mint>` is writable. In the name position `$dyn` is legal and harmless (a runtime one is minted under its own discriminator, a static one is not minted at all, and the two stay distinct), while a bare number is refused outright.
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…oundaryML#4536) A class you get out of `reflect.Package.compile` used to lose its identity the moment it crossed an interface method. BoundaryML#4516 fixed this for classes made with `reflect.class.new`; compiled packages were left out, and the PR said so. This finishes the job. ## What you get now **1. A compiled package's class is still itself inside an impl.** ```baml interface Probe<Out> { function same(self, t: type) -> bool throws never } class Holder<T> { function new() -> Holder<T> throws never { Holder {} } implements Probe<T> { function same(self, t: type) -> bool throws never { type.of<T>() == t } } } function main() -> bool throws unknown { let pkg = reflect.Package.compile({ "items.baml": #" class Item { value string } "# }) let item = (pkg.get_class("root.Item") ?? throw "missing Item").as_type() type Item = unreflect(item) Holder<Item>.new().same(item) // before: false — the impl body saw a type that described `Item` but was // not the value you passed in // now: true } ``` That `false` was the silent kind. The type printed the same, parsed the same and reflected the same — it just missed every lookup keyed by type, so a registry came back empty and a comparison against a stored type went the wrong way with no error anywhere. **2. Two packages that both declare `Item` each keep their own.** ```baml let first = reflect.Package.compile({ "a.baml": #"class Item { value string }"# }) let second = reflect.Package.compile({ "b.baml": #"class Item { value string }"# }) let a = (first.get_class("root.Item") ?? throw "missing A").as_type() let b = (second.get_class("root.Item") ?? throw "missing B").as_type() type A = unreflect(a) type B = unreflect(b) let holder = Holder<B>.new() holder.same(b) // before: false now: true holder.same(a) // false, before and after — B's holder never answers for A's Item ``` Before this PR neither question could be answered at all, because both packages spell their class `Item` and nothing downstream could tell them apart. Answering the second one `true` would have been worse than answering nothing, which is why BoundaryML#4516 declined both. **3. A statically declared `Item` is untouched**, including when a compiled package's `Item` is in scope right next to it. That was already correct and stays correct. ## Three wrong answers that came out of the same cause One name for several different classes did not only cost identity. Three things downstream read a class *by its name*, and each of them quietly answered with the wrong class. **A runtime type test matched another package's class.** ```baml let first = reflect.Package.compile({ "a.baml": #" class Item { value string } function Make() -> Item { Item { value: "a" } } "# }) let second = reflect.Package.compile({ "b.baml": #"class Item { value string }"# }) type First = unreflect((first.get_class("root.Item") ?? throw "missing A").as_type()) type Second = unreflect((second.get_class("root.Item") ?? throw "missing B").as_type()) let make = first.get_function<() -> First>("root.Make") ?? throw "missing root.Make" let value: unknown = make() value is First // true, before and after value is Second // before: true — a value the second package never made // now: false ``` Nothing reported an error. The `if value is Second { … }` branch simply ran on a value it was never given. **`ctx.output_format` described the wrong class.** The schema an LLM call sends is assembled from the definitions in scope, keyed by name, so the first `Item` to arrive answered for every later one: ```baml let first = reflect.Package.compile({ "a.baml": #"class Item { alpha string, next Item? }"# }) let second = reflect.Package.compile({ "b.baml": #"class Item { beta int, next Item? }"# }) type First = unreflect((first.get_class("root.Item") ?? throw "missing A").as_type()) type Second = unreflect((second.get_class("root.Item") ?? throw "missing B").as_type()) Render$render_prompt<Second[]>() // before: Item { alpha: string, next: Item or null } ← the FIRST package's fields // now: Item { beta: int, next: Item or null } ``` The model was being asked for a shape the caller never declared, and the answer it gave back then failed to parse — for a reason nothing in the program pointed at. **`baml.json` could not decode into a compiled package's class at all.** ```baml let pkg = reflect.Package.compile({ "items.baml": #"class Item { value string, count int }"# }) type Item = unreflect((pkg.get_class("root.Item") ?? throw "missing Item").as_type()) baml.json.from_string<Item>(#"{"value": "ok", "count": 2}"#) // before: JsonDecodeError — class `user.Item` not found // now: an Item ``` The decoder looks a class up by name against the program's own declarations, where a compiled package's `Item` was not — and the name it did find, or did not, had nothing to do with the package the caller meant. ## How Every compiled package used to name its classes exactly the way your own `.baml` files name theirs, so at runtime one package's `Item`, another's `Item`, and a static `Item` were three different types under one name. When a package is loaded, its own declarations now get an internal name that is unique to that package. Nothing else changes: the name that resolves your code, the name `pkg.get_class("root.Item")` takes, and the name every dependency links against are all still the plain one. ## What you see is unchanged The internal name is an identity token, never a spelling. Every surface that renders a type name strips it back out and shows the name the source wrote, so a compiled package's `Item` prints exactly what it printed before: ```baml item.to_string() // "Item" item.to_baml() // "class Item {\n value string\n}" ``` The same holds for `describe`, hover and completions, compiler diagnostics that mention the class, the schema `ctx.output_format` builds, `baml.json` decode errors, the coercion errors an LLM's output can produce, execution traces, and the `class_name` a host SDK (Python, TypeScript, Go, Java) reads off a returned value. Where a surface printed a package-qualified name before, it still prints `user.Item` — byte for byte what a plain declaration printed. **This also fixes the same leak for `reflect.class.new` classes.** Those have carried a unique internal name since they were introduced, and four surfaces were showing it: | surface | before | now | | --- | --- | --- | | LLM-output coercion error | `Expected user.$dyn.0.Item, got …` | `Expected user.Item, got …` | | `baml.json` decode error | ``expected JSON object for class `user.$dyn.0.Item` `` | ``expected JSON object for class `user.Item` `` | | diagnostic from a runtime compile | ``expected `int`, found `root.$dyn.0.Item` `` | ``expected `int`, found `Item` `` | | `class_name` at the host boundary | `user.$dyn.0.Item` | `user.Item` | The number in those names was a per-process counter that changed run to run, so nothing could have been depending on it. Masking it is a bugfix, not a break. ## Notes - **Renaming had to be all-or-nothing.** A first attempt renamed only the class objects and left the compiled code that mentions them alone. The two spellings then disagreed in three separate places: the package's own `type.of<Item>()` stopped matching, an interface stopped resolving, and `get_function` rejected a signature that matched perfectly. So the rename covers everything the package was compiled into — field types, method signatures, interface declarations, impl rules, type aliases — in one pass. - **One honest behavior change.** If a package declares its own `Item` *and* imports a dependency that also exports an `Item`, those were one name to the runtime before, and both resolved to the package's own class. They still resolve the same way, but a type value for one no longer tests equal to a type value for the other. They were never the same type; the old answer was an accident of them sharing a name. - **Sessions are unchanged.** Declarations you make inside a `Session` still don't carry their identity across an interface method — the same limitation as before, not a new one. A Session re-loads its whole history on every submission, so giving its declarations a per-package name first needs an answer to what a declaration's identity means across submissions. That is a separate question. - **Derived types are unchanged.** `t.array()`, `t.optional()` and `type.meta(...)` still produce a fresh type on every evaluation and still don't survive an interface method. That was ratified deliberately and this PR does not touch it. - **Nothing about a statically compiled program changes.** The rename runs only when a runtime package is loaded. ## Tests The two tests BoundaryML#4516 wrote to pin the gap now pin the fix instead: the one that recorded "definitions survive but identity does not" asserts identity survives, and the one that recorded two packages declining to answer asserts each answers with its own and refuses the other's. Its sibling — a static class that must not be answered from a runtime one of the same name — is unchanged and still green. New, for the three wrong answers above: a runtime type test that must not match a foreign package's class, and an `ctx.output_format` schema that must describe each package's own fields. New, for rendering: every surface that moved is pinned for **both** origins that mint — `Package.compile` and `reflect.class.new` — with the exact spelling asserted, plus a blanket "no internal name anywhere in the output": - the coercion error schema-aligned parsing produces (`Expected user.Item, …`); - the `baml.json` decode error (``expected JSON object for class `user.Item` ``), which also pins that a compiled package's class resolves at all; - the `class_name` on the instance a host receives (`user.Item`); - a diagnostic from a runtime compile that has to name a mounted minted class (`Item`); - and the earlier four-way pin on `to_string`, `to_baml`, the `ctx.output_format` schema and a contract diagnostic. Plus unit tests that a minted name renders identically to the plain name it was minted from, that the rename reaches a class mentioned inside its own field type, leaves an imported class at its owner's name, leaves a dependency's type alone, and gives two packages two distinct names for the same declaration. <!-- This is an auto-generated comment: release notes by coderabbit.ai --> ## Summary by CodeRabbit - **Bug Fixes** - Fixed type identity conflicts when compiled packages contain classes or enums with the same name. - Corrected interface dispatch, type checks, JSON conversion, schemas, and runtime diagnostics for package-specific types. - Prevented internal runtime identifiers from appearing in user-facing names and error messages. - **Documentation** - Updated the changelog with affected scenarios and expected behavior. <!-- end of auto-generated comment: release notes by coderabbit.ai -->
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Follows #4501, which carried runtime definitions through interface dispatch and closed
by naming what it did not fix:
This is that change. Antonio ratified carrying the exact values through, on the same
discipline as the defs carry.
The hole
VirtualCallresolves the impl from the receiver's realizedSelfand seeds the calleeframe from
resolver.realize_frame, which produces realized types only. The exactTypeValues the caller minted reach the callee frame'sFrameTypeMetadata.valuesfromappend_virtual_method_type_argsalone — i.e. from method-level type arguments. Thereceiver's class-level slots got definitions but no values, so
LoadType(TypeArgRef)inthe body fell through to
alloc_static_type_with_defsand derived a fresh staticdigest.
The result was a type value that named the same definition and rendered, parsed and
reflected identically, but was
==-distinct from the one the caller passed:Structural checks all passed, so the failure was silent: a map keyed by type missed, an
==against a stored type went the wrong way, and nothing reported an error.The direct paths were already correct — a generic function call and a generic-class
instance method both thread the call site's type-argument operands, values included. Only
the resolver path dropped them.
The fix
A runtime definition records the mint it was created with (
RuntimeTypeProvenance), sothe caller's identity can be read back off the definition instead of derived afresh —
never a new mint, which is what BEP-066 I-1 requires. The interface operand already
carries the definitions the receiver's class-level slots name (that is #4501's overlay),
so those two facts together reconstruct the exact value:
BexVm::runtime_declaration_identity(definition_ptr)rebuilds the minted value for aruntime class or enum, adding the definition's own pointer back to its provenance defs.
type.of_valuewas already doing exactly this inline; both now share the oneconstruction.
BexVm::minted_declaration_value(ty, defs)resolves a frame slot's realized typeagainst the operand's overlay, only for a mint-unique name — see below. The
reconstructed value must also describe the same type or it is refused, so a decorated or
parameterized spelling can never borrow a definition's mint.
VirtualCallfills the owner slots with what that recovers and hands them to the calleeframe ahead of any method-level slots, which keep their existing positions.
Why recovery is restricted to
$dynnamesA
DynTypeDefsis keyed byQualifiedTypeName, and only aruntime_localname carriesits mint in the name (
user.$dyn.N.Foo— whatreflect.class.newandreflect.enum.newproduce). A static declaration and a compiled package's declaration are both plain
user.Foo. An overlay also reaches a frame whether or not the spelling being recovered isthe one that pulled it in, because
LoadTypestaples the whole frame overlay onto anythingmaterialized there.
Matching an ordinary name against the overlay therefore answers from a different
definition. Both shapes are now regressions in this PR, and both were verified failing
without the
is_runtime_mintedgate:Holder<Item>in a frame that also bound a compiled package'sItemtype.of<T>() == type.of<Item>()is false,== package_itemis truetrue,falseItem, dispatching onHolder<B>== b_itemis false,== a_itemis truefalse,falseThe first is a regression against canary, which got it right by never recovering at all.
The second is
==lying about a type it is not, which is worse than not knowing. Soanything but a mint-unique name declines and the body re-derives normally.
Cost
The added work is gated on the interface operand carrying definitions at all. A static
interface operand leaves
iface_defsempty, so the owner-slot walk never runs and thevalues vec never allocates; the existing no-type-args fast path is entered on exactly the
same condition as before. The four
interfaces/*speedtest workloads are static-interfacedispatch and are structurally untouched by that reasoning — but note honestly that no
bench covers the runtime-definitions dispatch path, and CodSpeed was not run for this
branch, so the "definitions present" case is argued, not measured.
When the operand does carry definitions, the walk is
O(owner slots)(0–2 in practice)map lookups, and each recovered slot clones the definition's provenance defs — the same
O(defs)shape as the overlay clone #4501's F4 note flagged. Note the frames this runs inare exactly the ones where
LoadType's static cache is already disabled (a non-emptyoverlay disables it), so the recovery does not add an allocation that was previously
avoided.
Arc<DynTypeDefs>remains the lever for both; it is not a drop-in, because GCforwarding rewrites the pointers inside a
DynTypeDefsin place, so sharing would haveto be unshared again exactly where it pays off. That reasoning is now a comment at the
clone rather than only in a PR body.
Documented gaps
Both are the same shape — the receiver is the only thing that could carry the identity, and
Instancedrops its class type-argument values at construction (it stores realized typesonly;
Object's 64-byte assert and its Borsh wire form make a values lane a change to theobject model, not an implementation detail).
Derived runtime types.
t.array(),t.optional()andtype.meta(…)mint a freshruntime id per evaluation and attach it to no definition, so there is nothing to read back:
Holder<RuntimeOutput[]>'s impl body still sees a re-derived value. The alternative —deriving a derived type's mint from its parts — would make
t.array() == t.array()true inordinary code too, and contradicts I-1's "one per constructor evaluation".
Declarations from a compiled
reflect.Package. Their names are not mint-unique, whichis exactly the restriction above. Their definitions still travel (#4501), so an impl body
can read, render and parse the type; it just does not hold the caller's identity token for
it.
runtime_package_declarations_keep_definitions_but_not_identitypins that contractrather than leaving it silent. The honest futures are to give compiled-package declarations
mint-unique names, or to carry the values on the receiver — the same lever as the derived
case.
Neither is a ruling this PR should make; written up separately.
Follow-up noted in code, not fixed
execute_call_from_locals_offset_with_type_argsrestorespending_call_type_values(the rooted copy) before reading
options.type_values, which borrows an unrooted callerlocal. A collection in between would leave those pointers stale. It is unreachable as
written — the callee-entry helper pushes a frame and sizes the eval stack with no TLAB
allocation, and the native path that can allocate pushes no bytecode frame, so the write
guard declines — and it predates this PR (#4501 introduced the lane). Recorded as a comment
because this lane now carries recovered identities too.
Tests
Runtime-output oracles in
runtime_type_bindings.rs:minted_type_identity_survives_interface_dispatchinterface_impl_methods_look_up_a_type_keyed_registry==inside the impl, with a same-shape same-name entry as the in-test missdispatch_identity_separates_distinct_mints_and_leaves_static_generics_aloneHolder<string>) unchanged in both directionsdispatch_identity_covers_owner_and_method_slots_togetherdispatch_identity_covers_a_runtime_enum_slotstatic_class_slots_are_not_answered_from_a_same_named_runtime_definitionsame_named_declarations_from_two_packages_do_not_cross_matchruntime_package_declarations_keep_definitions_but_not_identityUnit tests in
vm.rspin the owner/method slot alignment: recovered owner values precedemethod-level slots, and a non-generic method still receives them.
Verification
Focused:
runtime_type_bindings(18/18),bex_vmunit + integration. The two collisionregressions were re-verified failing with the name gate removed (
false|truein bothcases). Full pinned gate below.
Summary by CodeRabbit
Bug Fixes
Tests