1. Enhancements

Elixir

• [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
• [Macro] Add __escape__/1 callback so structs can escape references and other runtime data types in Macro.escape/1
• [OptionParser] Support the :regex type
• [OptionParser] Enhance parsing error to display available options
• [String] Update to Unicode 17.0.0

ExUnit

• [ExUnit] Set a process label for each test

Logger

• [Logger] Accept any enumerable in Logger.metadata/1

Mix

• [mix format] Add options to mix format to allow excluding of files
• [mix test] Add --name-pattern option to mix test
• [Mix.install/2] Support the :compilers option

2. Bug fixes

Elixir

• [Code] Return error on invalid unicode sequences in Code.string_to_quoted/2 instead of raising
• [Code] Properly handle column annotation for in in not in expressions
• [Enum] Fix infinite loop on Enum.take/2 with negative index on empty enumerable
• [Inspect] Inspect ill-formed structs as maps
• [Kernel] Properly increment metadata newline when ? is followed by a literal newline character

ExUnit

• [ExUnit.Assertions] Fix order in ExUnit results when listing pinned variables
• [ExUnit.Assertions] Raise if attempting to raise an assertion error with invalid message (not a binary)

IEx

• [IEx] Abort pipelines when there is an error in any step along the way

Mix

• [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 test] Prevent mix test from overriding :failures_manifest_path option

3. Hard deprecations

Elixir

• [Code] Warn if line-break characters outside of \r and \r\n are 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