Changelog

[0.4.0] - 2026-06-14

Elixir 1.20 and Erlang/OTP 29 support, plus safer atom creation.

Minimum Elixir version is now 1.20 (was 1.18).
Safe UTF-8 is now the default atom-creation path. term::make_atom and term::make_atom_len now use enif_make_new_atom* (UTF-8, returning a fallible Term? with ATOM_TABLE_FULL) instead of the old enif_make_atom* (Latin1, infallible, aborts the VM when the atom table is full). The previous behavior is available unchanged as make_atom_latin1 / make_atom_latin1_len. make_atom_utf8 / make_atom_utf8_len remain as @deprecated aliases of the new defaults.

Erlang/OTP 29 support. The NIF ABI is unchanged: c3nif still declares ERL_NIF 2.17, which loads on OTP 26 through 29 (OTP 29's 2.18 is major-compatible). New ERL_NIF 2.18 bindings are available for OTP-29-only use — enif_term_size, enif_get_atom_cache_index, enif_max_atom_cache_index — but the declared minor version is intentionally kept at 17 so NIFs remain loadable on OTP 26+; calling a 2.18 function on an older runtime fails NIF load.
CI on Erlang/OTP 29 + Elixir 1.20, building the library and running the integration suite (which compiles and load_nifs every fixture) as a build-and-load smoke test.

Elixir 1.20 deprecations and warnings: File.stream!/3 argument order in C3nif.Precompiled.file_checksum/1, a now-unused module-level require Logger in C3nif.Compiler, and unreachable case clauses in the integration tests flagged by the 1.20 type checker. Added :test_ignore_filters so the test-support module no longer trips the new mix test file-pattern warning.

Migration to C3 0.8.

Minimum C3 compiler version is now 0.8.0 (was 0.7.11). The codebase was updated for 0.8 language changes:
- @extern("name") bindings replaced with @cname("name") (the old attribute was removed).
- Type-size access changed from Type.sizeof to Type::size.
- The Allocator interface now takes signed sz sizes/alignments, and implicit signed↔unsigned conversions were removed, so BeamAllocator gained explicit casts.
- Macro method dispatch via value.#param(...) was removed; the @require_type macro now uses value.$eval($stringify(#param))(...).

Modernization release: C3 0.7.11 + ERL_NIF 2.17 (OTP 26+), with a new precompiled NIF distribution pipeline.

Minimum C3 compiler version is now 0.7.11 (was 0.6.0). Updates all source to the current C3 syntax: enum Foo : const CInt declarations were converted to constdef X : inline CInt, and fault-creation sites use return X~; instead of the deprecated return X?;.
Minimum OTP version is now 26 (was effectively OTP 21). Required for ERL_NIF 2.17 APIs such as enif_make_new_atom, enif_set_option, and UTF-8 atom encoding.
Resource registry API hard break. The O(n) string-keyed lookup has been removed. resource::register_type now returns an ErlNifResourceType* handle that callers must cache at load time, and both resource::alloc and resource::get take that handle instead of a string name. The 32-type cap (MAX_RESOURCE_TYPES) and the internal registry arrays are gone. get_resource macro and c3nif.c3 aliases were updated to match. See guides/resources.md for the new pattern.

ERL_NIF 2.17 API surface. Bound enif_make_new_atom, enif_make_new_atom_len, enif_get_string_length, and the three enif_set_option variants (DELAY_HALT, ON_HALT, ON_UNLOAD_THREAD). Added the ErlNifCharEncoding.UTF8 variant and ErlNifOption, OnHaltFn, OnUnloadThreadFn types.
UTF-8 atom helpers in term.c3: make_atom_utf8, make_atom_utf8_len, make_existing_atom_utf8. Unlike the older make_atom path, these return an ATOM_TABLE_FULL fault instead of aborting the VM when the atom table is exhausted.
Halt-safety wrappers in scheduler.c3: delay_halt, set_on_halt, set_on_unload_thread. Use from a NIF's load callback to keep long-running dirty NIFs from being killed mid-operation during init:stop/0,1.
Precompiled NIF distribution. New C3nif.Precompiled module and mix c3nif.precompile task for building, archiving, and SHA-256 verifying prebuilt shared libraries per target triple. Consumers opt in via use C3nif, precompiled: [base_url: ..., version: ..., checksums_path: ...] and get automatic source-build fallback when a precompiled artifact isn't available. Mirrors the rustler_precompiled workflow. See guides/precompilation.md.

C3nif.Compiler.compile/1 now accepts an optional :target key that is forwarded to c3c build --target <triple>. The c3c invocation was refactored into a shared run_c3c/2 helper used by both the regular compile path and the precompile task.
Removed the unused jason dependency; C3nif uses the stdlib JSON module (Elixir 1.18+).

test/integration/binary_test.exs copy-binary assertion no longer depends on OTP 25 internal allocation-size reporting.

Fix Application.app_dir/2 errors during initial compilation of projects using c3nif