fix(interpreter): fresh mutable containers get heap identity, like literals - #143
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…terals
set()/list()/dict() constructor results (and list(iterable)) returned
bare values, so an in-place mutation reached through a reference mutated
a throwaway copy: `index.setdefault(w, set()).add(name)` left every set
in the dict empty — the classic inverted-index idiom silently produced
no hits. Literals ({...}, []) already heap-allocate; constructors now do
too, via handle_builtin_result, so aliasing and mutation-through-
intermediate-receiver behave like CPython.
Set in-place mutators (add/remove/discard/pop/clear/update/…) move to
the :ok_raw path so their {:mutate, new, ret} writeback reaches the heap
object — the same wiring list.append and dict mutators already had.
json.dumps grows a {:ref} deref in apply_default so default=list (which
now returns a ref) terminates instead of recursing on itself.
Six regression tests cover the setdefault idioms, constructor aliasing,
list(iterable) mutability, and the json.dumps(default=list) fixpoint.
This fix was authored in a parallel working session (its differential
CPython/VM/Wasm harness found the bug); this PR lands it with formatting,
a widened set_method spec for Dialyzer, and the regression tests.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KuxYKoh8pXEna5ohZUgJsn
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…rg (#145) * feat: OTel attributes= kwarg, WasmGC target, and the differential harness Three pieces from the wasm working session, extracted onto main (the container-identity fix landed separately as #143): - opentelemetry: start_as_current_span honors the attributes= kwarg, seeding the span at open; merges with set_attribute calls. Two tests. - Pyex.Wasm: the `mix wasm.build` entry point — pyrun/3 runs a program in a fresh Ctx against an in-memory VFS and returns stdout, footprint, final files, and BOTH runtime and app spans as JSON. The beam2wasm compiler is a sibling-checkout dev dep, loaded only when the checkout exists, so CI and consumers resolve deps without it (the wasm: project config is inert without the dep). - test/differential: a three-executor harness (CPython · pyex-VM · pyex-Wasm) that auto-localizes divergences — CPython≠VM is an interpreter bug, VM≠Wasm is a compiler bug — gated by a checked-in LEDGER of known divergences. Aliasing lens (constructor × storage × mutation product) plus a 25-program realistic corpus; 79/79 green at time of extraction. Runs via `mix run test/differential/run.exs` (needs wasm/pyex.wasm and python3), not in `mix test`. Also: span_cm loses a dead default arg (warning), and Wasm.pyrun's rescue clause interpolates type-safely without Exception.message/1 (protocol dispatch the wasm target can't lower). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KuxYKoh8pXEna5ohZUgJsn * drop the wasm target + harness: moving to the pyex.dev composition repo The ../elixir_wasm path-based dev dep was too fragile to ship, even guarded. The wasm entry point, build config, and differential harness move to a third project that composes pyex + beam2wasm via git deps and owns the pyex.dev site and edge API. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KuxYKoh8pXEna5ohZUgJsn --------- Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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Summary
set()/list()/dict()constructor results (andlist(iterable)) returned bare values, so an in-place mutation reached through a reference mutated a throwaway copy. The flagship symptom, straight from the playground's search-index example:Literals (
{...},[]) already heap-allocate for identity; constructors now do too (handle_builtin_resultallocs fresh mutable containers), so aliasing and mutation-through-intermediate-receiver behave like CPython.add/remove/discard/pop/clear/update/difference_update/…) move to the:ok_rawpath so their{:mutate, new, ret}writeback reaches the heap object — the same wiringlist.appendand dict mutators already had.list(...)clauses route through onealloc_listhelper;{:iter_to_list, ...}results heap-alloc on the way out.json.dumpsgrows a{:ref}deref inapply_default, sodefault=list(which now returns a ref) recurses into the concrete-value clauses instead of re-invokingdefaulton the ref forever.set_method's@specwidened for the:ok_rawshape (Dialyzer).Six regression tests: the inverted-index
setdefault(w, set()).add(...)idiom,dict()-via-setdefaultsubscript writes,list()/list(iterable)aliasing + mutability, set mutators through an alias, and thejson.dumps(default=list)fixpoint.Provenance
Authored in a parallel working session, whose differential CPython/VM/Wasm harness surfaced the bug; landed here with formatting, the spec fix, and tests. The harness itself ships separately with the wasm build config.
Test plan
mix format --check-formattedmix compile --warnings-as-errors(modulo the three pre-existing 1.20.2-local warnings on main)mix test— 6518/6519 (the one failure is the known local-OTP zipfile CRC-message artifact, present on main)mix dialyzer— clean🤖 Generated with Claude Code
https://claude.ai/code/session_01KuxYKoh8pXEna5ohZUgJsn