v1.19.0
Official announcement: https://elixir-lang.org/blog/2025/10/16/elixir-v1-19-0-released/
1. Enhancements
Elixir
- [Access] Add
Access.values/0for traversing maps and keyword lists values - [Base] Add functions to verify if an encoding is valid, such as
valid16?,valid64?, and so forth - [Calendar] Support 2-arity options for
Calendar.strftime/3which receives the whole data type - [Code] Add
:migrate_call_parens_on_pipeformatter option - [Code] Add
:indentationoption toCode.string_to_quoted/2 - [Code.Fragment] Preserve more block content around cursor in
container_cursor_to_quoted - [Code.Fragment] Add
:block_keyword_or_binary_operatortoCode.Fragmentfor more precise suggestions after operators and closing terminators - [Code.Fragment] Add
Code.Fragment.lines/1 - [Enum] Provide more information on
Enum.OutOfBoundsError - [Inspect] Allow
optional: :allwhen deriving Inspect - [Inspect.Algebra] Add optimistic/pessimistic groups as a simplified implementation of
next_break_fits - [IO.ANSI] Add ANSI codes to turn off conceal and crossed_out
- [Kernel] Raise when U+2028 and U+2029 characters are present in comments and strings to avoid line spoofing attacks
- [Kernel] Include the line for the previous clause in errors/warnings related to conflicts between defaults on function definitions
- [Kernel] Support
min/2andmax/2as guards - [Kernel.ParallelCompiler] Add
each_long_verification_thresholdwhich invokes a callback when type checking a module takes too long - [Kernel.ParallelCompiler] Include lines in
== Compilation error in file ... ==slogans - [Macro] Print debugging results from
Macro.dbg/3as they happen, instead of once at the end - [Macro] Add
__escape__/1callback so structs can escape references and other runtime data types inMacro.escape/1 - [Module] Do not automatically load modules after their compilation, guaranteeing a more consistent compile time experience and drastically improving compilation times
- [OptionParser] Support the
:regextype - [OptionParser] Enhance parsing error to display available options
- [Protocol] Type checking of protocols dispatch and implementations
- [Regex] Add
Regex.to_embed/2which returns an embeddable representation of regex in another regex - [Regex] Raise error message when regexes are used as default values in struct fields for compatibility with Erlang/OTP 28
- [Registry] Add key-based partitioning of duplicate registries
- [String] Add
String.count/2to count occurrences of a pattern - [String] Update to Unicode 17.0.0
ExUnit
- [ExUnit] Set a process label for each test
- [ExUnit.CaptureLog] Parallelize log dispatch when multiple processes are capturing log
- [ExUnit.Case] Add
:test_groupto the test context - [ExUnit.Doctest] Support ellipsis in doctest exceptions to match the remaining of the exception
- [ExUnit.Doctest] Add
:inspect_optsoption for doctest
IEx
- [IEx] Support multi-line prompts (due to this feature,
:continuation_promptand:alive_continuation_promptare no longer supported as IEx configuration) - [IEx.Autocomplete] Functions annotated with
@doc group: "Name"metadata will appear within their own groups in autocompletion
Logger
- [Logger] Accept any enumerable in
Logger.metadata/1
Mix
- [mix] Add support for
MIX_PROFILE_FLAGSto configureMIX_PROFILE - [mix compile] Debug the compiler and type checker PID when
MIX_DEBUG=1and compilation/verification thresholds are met - [mix compile] Add
Mix.Tasks.Compiler.reenable/1 - [mix deps.compile] Support
MIX_OS_DEPS_COMPILE_PARTITION_COUNTfor compiling deps concurrently across multiple operating system processes - [mix help] Add
mix help Mod,mix help :mod,mix help Mod.fun,mix help Mod.fun/arity, andmix help app:package - [mix format] Add options to mix format to allow excluding of files
- [mix test] Add
--name-patternoption tomix test - [mix test] Allow to distinguish the exit status between warnings as errors and test failures
- [mix xref graph] Add support for
--format json - [mix xref graph] Emit a warning if
--sourceis part of a cycle - [Mix] Support the
:compilersoption - [Mix.Task.Compiler] Add
Mix.Task.Compiler.run/2
2. Bug fixes
Elixir
- [Code] Return error on invalid unicode sequences in
Code.string_to_quoted/2instead of raising - [Code] Properly handle column annotation for
ininnot inexpressions - [DateTime] Do not truncate microseconds regardless of precision in
DateTime.diff/3 - [Enum] Fix infinite loop on
Enum.take/2with negative index on empty enumerable - [File] Properly handle permissions errors cascading from parent in
File.mkdir_p/1 - [Inspect] Inspect ill-formed structs as maps
- [Kernel] Properly increment metadata newline when
?is followed by a literal newline character - [Kernel]
not_a_map.keynow raisesBadMapErrorfor consistency with other map operations - [Protocol]
defstruct/1anddefexception/1are now disabled insidedefprotocolas to not allow defining structs/exceptions alongside a protocol - [Regex] Fix
Regex.split/2returning too many results when the chunk being split on was empty (which can happen when using features such as/K) - [Stream] Ensure
Stream.transform/5respects suspend command when its inner stream halts - [URI] Several fixes to
URI.merge/2related to trailing slashes, trailing dots, and hostless base URIs
ExUnit
- [ExUnit.Assertions] Fix order of pinned variables in failure reports
- [ExUnit.Assertions] Raise if attempting to raise an assertion error with invalid message (not a binary)
- [ExUnit.Case] Do not crash on empty test unit groups
IEx
- [IEx] Abort pipelines when there is an error in any step along the way
Mix
- [mix cmd] Preserve argument quoting in subcommands by no longer performing shell expansion. To revert to the previous behaviour, pass
--shellbefore the command name - [mix compile] Fix bug where reverting changes to an external resource (such as HEEx template) after a compilation error would make it so the source module would not be compiled
- [mix compile] Avoid failures when locking compilation across different users
- [mix compile] Fix race condition when renaming files used by the compilation lock
- [mix format] Ensure the formatter does not go over the specified limit in certain corner cases
- [mix release] Fix
RELEASE_SYS_CONFIGfor Windows 11 - [mix test] Ensure modules are preloaded in
mix test --slowest-modules=N - [mix xref graph] Provide more consistent output by considering strong connected components only when computing graphs
3. Soft deprecations (no warnings emitted)
Elixir
- [Inspect.Algebra]
next_break_fitsis deprecated in favor ofoptimistic/pessimisticgroups - [Node]
Node.start/2-3is deprecated in favor ofNode.start/2with a keyword list
Mix
- [mix compile]
--no-protocol-consolidationis deprecated in favor of--no-consolidate-protocolsfor consistency withmix.exsconfiguration - [mix compile.protocols] Protocol consolidation is now part of
compile.elixirand the task itself has no effect
4. Hard deprecations
Elixir
- [Code] Warn if line-break characters outside of
\rand\r\nare found in strings according to UX#55. This warning will be fast-tracked into an error for security reasons in Elixir v1.20, following a similar rule to bidirectional control characters. They will already raise if found in comments - [Code] The
on_undefined_variable: :warnis deprecated. Relying on undefined variables becoming function calls will not be supported in the future - [File] Passing a callback as third argument to
File.cp/3is deprecated, pass it as aon_conflict: callbackoption instead - [File] Passing a callback as third argument to
File.cp_r/3is deprecated, pass it as aon_conflict: callbackoption instead - [Kernel] The struct update syntax, such as
%URI{uri | path: "/foo/bar"}, now requires the given variable (or expression) to explicitly pattern match on the struct before it can be updated. This is because, thanks to the type system, pattern matching on structs can find more errors, more reliably, and we want to promote its usage. Once pattern matching is added, you may optionally convert the struct update syntax into the map update syntax%{uri | path: "/foo/bar"}with no less of typing guarantees - [Kernel.ParallelCompiler] Passing
return_diagnostics: trueas an option is required oncompile,compile_to_pathandrequire
Logger
- [Logger] The
:backendsconfiguration is deprecated, either set the:default_handlerto false or start backends in your application start callback
Mix
- [mix] The
:default_task,:preferred_cli_env, and:preferred_cli_targetconfiguration insidedef projectin yourmix.exshas been deprecated in favor of:default_task,:preferred_envsand:preferred_targetsinside thedef clifunction - [mix do] Using commas as task separator in
mix do(such asmix do foo, bar) is deprecated, use+instead (as inmix do foo + bar)