Julia v1.12 Release Notes
========================

New language features
---------------------

Language changes
----------------

 - When methods are replaced with exactly equivalent ones, the old method is no
   longer deleted implicitly simultaneously, although the new method does take
   priority and become more specific than the old method. Thus if the new
   method is deleted later, the old method will resume operating. This can be
   useful to mocking frameworks (such as in SparseArrays, Pluto, and Mocking,
   among others), as they do not need to explicitly restore the old method.
   While inference and compilation still must be repeated with this, it also
   may pave the way for inference to be able to intelligently re-use the old
   results, once the new method is deleted. ([#53415])

 - Macro expansion will no longer eargerly recurse into into `Expr(:toplevel)`
   expressions returned from macros. Instead, macro expansion of `:toplevel`
   expressions will be delayed until evaluation time. This allows a later
   expression within a given `:toplevel` expression to make use of macros
   defined earlier in the same `:toplevel` expression. ([#53515])

Compiler/Runtime improvements
-----------------------------

Command-line option changes
---------------------------

* The `-m/--module` flag can be passed to run the `main` function inside a package with a set of arguments.
  This `main` function should be declared using `@main` to indicate that it is an entry point.

Multi-threading changes
-----------------------

Build system changes
--------------------

New library functions
---------------------

* `logrange(start, stop; length)` makes a range of constant ratio, instead of constant step ([#39071])
* The new `isfull(c::Channel)` function can be used to check if `put!(c, some_value)` will block. ([#53159])
* `waitany(tasks; throw=false)` and `waitall(tasks; failfast=false, throw=false)` which wait multiple tasks at once ([#53341]).

New library features
--------------------

* `invmod(n, T)` where `T` is a native integer type now computes the modular inverse of `n` in the modular integer ring that `T` defines ([#52180]).
* `invmod(n)` is an abbreviation for `invmod(n, typeof(n))` for native integer types ([#52180]).
* `replace(string, pattern...)` now supports an optional `IO` argument to
  write the output to a stream rather than returning a string ([#48625]).
* `sizehint!(s, n)` now supports an optional `shrink` argument to disable shrinking ([#51929]).
* New function `Docs.hasdoc(module, symbol)` tells whether a name has a docstring ([#52139]).
* New function `Docs.undocumented_names(module)` returns a module's undocumented public names ([#52413]).
* Passing an `IOBuffer` as a stdout argument for `Process` spawn now works as
  expected, synchronized with `wait` or `success`, so a `Base.BufferStream` is
  no longer required there for correctness to avoid data races ([#52461]).
* After a process exits, `closewrite` will no longer be automatically called on
  the stream passed to it. Call `wait` on the process instead to ensure the
  content is fully written, then call `closewrite` manually to avoid
  data-races. Or use the callback form of `open` to have all that handled
  automatically.
* `@timed` now additionally returns the elapsed compilation and recompilation time ([#52889])
* `filter` can now act on a `NamedTuple` ([#50795]).
* `tempname` can now take a suffix string to allow the file name to include a suffix and include that suffix in
  the uniquing checking ([#53474])
* `RegexMatch` objects can now be used to construct `NamedTuple`s and `Dict`s ([#50988])

Standard library changes
------------------------

#### StyledStrings

#### JuliaSyntaxHighlighting

#### Package Manager

#### LinearAlgebra

#### Logging

#### Printf

#### Profile

#### Random

#### REPL

#### SuiteSparse

#### SparseArrays

#### Test

#### Dates

#### Statistics

#### Distributed

#### Unicode

#### DelimitedFiles

#### InteractiveUtils

Deprecated or removed
---------------------

External dependencies
---------------------

Tooling Improvements
--------------------

<!--- generated by NEWS-update.jl: -->