Announcing Scala.js 1.18.0.

_config.yml

@@ -64,7 +64,7 @@ colors:  #in hex code if not noted else
 
 ### VERSIONS ###
 versions:
-  scalaJS: 1.17.0
+  scalaJS: 1.18.0
   scalaJSBinary: 1
   scalaJS06x: 0.6.33
   scalaJS06xBinary: 0.6

_data/library/versions.yml

@@ -34,3 +34,4 @@
 - 1.13.0
 - 1.16.0
 - 1.17.0
+- 1.18.0

_posts/news/2025-01-07-announcing-scalajs-1.18.0.md

@@ -0,0 +1,165 @@
+---
+layout: post
+title: Announcing Scala.js 1.18.0
+category: news
+tags: [releases]
+permalink: /news/2025/01/07/announcing-scalajs-1.18.0/
+---
+
+
+We are pleased to announce the release of Scala.js 1.18.0!
+
+This release drops support for Scala 2.12.{2-5} and 2.13.{0-2}.
+Other than that, it is mostly a bugfix release.
+
+This release also contains a number of internal changes to the intermediate representation and linker.
+These are not externally visible, except for users who directly manipulate the IR and/or linker.
+They pave the way for upcoming changes that are still ongoing work.
+
+Read on for more details.
+
+<!--more-->
+
+## Getting started
+
+If you are new to Scala.js, head over to [the tutorial]({{ BASE_PATH }}/tutorial/).
+
+If you need help with anything related to Scala.js, you may find our community [in `#scala-js` on Discord](https://discord.com/invite/scala) and [on Stack Overflow](https://stackoverflow.com/questions/tagged/scala.js).
+
+Bug reports can be filed [on GitHub](https://github.com/scala-js/scala-js/issues).
+
+## Release notes
+
+If upgrading from Scala.js 0.6.x, make sure to read [the release notes of Scala.js 1.0.0]({{ BASE_PATH }}/news/2020/02/25/announcing-scalajs-1.0.0/) first, as they contain a host of important information, including breaking changes.
+
+This is a **minor** release:
+
+* It is backward binary compatible with all earlier versions in the 1.x series: libraries compiled with 1.0.x through 1.17.x can be used with 1.18.0 without change.
+* It is *not* forward binary compatible with 1.17.x: libraries compiled with 1.18.0 cannot be used with 1.17.x or earlier.
+* It is *not* entirely backward source compatible: it is not guaranteed that a codebase will compile *as is* when upgrading from 1.17.x (in particular in the presence of `-Xfatal-warnings`).
+
+As a reminder, libraries compiled with 0.6.x cannot be used with Scala.js 1.x; they must be republished with 1.x first.
+
+## Changes with compatibility concerns
+
+### Enforce stricter rules on the use of `this` in the IR of constructors
+
+Exceptionally, **this is theoretically a binary-breaking change**.
+It is possible for previously valid IR (Intermediate Representation, as published in binaries on Maven Central) to be rejected by Scala.js 1.18.0.
+
+We now enforce, during IR checking (by default, only enabled in `fullLink` builds), that constructors abide by stricter rules.
+Before calling their `super` constructor (or delegate `this()` constructor), they may not refer to the `this` instance.
+The only exception is to *assign* a field, as in `this.foo = bar`.
+This restriction is in line with a similar rule in JVM bytecode.
+
+Unfortunately, the Scala.js compiler for Scala 2.x was previously generating IR that is invalid according to the new rule in one corner case situation.
+If there is a `try..catch` expression inside an argument to the `super` constructor, the compiler may lift it to a separate method.
+We compiled that method as an *instance* method, using the `this` value, instead of compiling it as a *static* method.
+
+Here is an example:
+
+{% highlight scala %}
+class Parent(val i: Int)
+
+class Child extends Parent({
+  val p = try Integer.parseInt("foo") catch { case _: NumberFormatException => 42 }
+  p
+})
+
+object Test {
+  def main(args: Array[String]): Unit =
+    println(new Child().i)
+}
+{% endhighlight %}
+
+If your application depends on a library that contained such a code shape, you may hit the following IR checking error at link time in Scala.js 1.18.0.
+
+{% highlight none %}
+[error] ...: Restricted use of `this` before the super constructor call
+[error] There were 1 ClassDef checking errors.
+{% endhighlight %}
+
+If that is the case, the library needs to be recompiled with Scala.js 1.18.0 or later to be usable again.
+Make sure to [tell us on the relevant PR](https://github.com/scala-js/scala-js/pull/5019) if that happens.
+
+In order to mitigate the impact of this change, we conducted an audit of (the latest version of) all Scala.js libraries published to Maven Central.
+We did not find any library that violated the new rule.
+You may still run into the issue if you depend on a private library.
+
+As a temporary, stop-gap measure, you may silence the error with the following setting:
+
+{% highlight scala %}
+Compile/fullLinkJS/scalaJSLinkerConfig ~= { _.withCheckIR(false) }
+{% endhighlight %}
+
+However that will start causing real issues once we leverage the new restriction for better optimizations.
+
+### Drop support for Scala 2.12.2 to 2.12.5 and 2.13.0 to 2.13.2
+
+In order to reduce our maintenance burden and ease further development, Scala.js 1.18.0 drops support for Scala 2.12.2 to 2.12.5 and 2.13.0 to 2.13.2.
+Scala 2.12.6+ and 2.13.3+ are still supported.
+
+We still had a number of dedicated code paths, special cases and exceptions for these versions in our codebase.
+Moreover, we occasionally hit compiler bugs in early 2.12.x versions, which imposed constraints on how we wrote our code.
+
+### The Wasm backend now requires full support of `try_table` (notably Node.js 23)
+
+If you are using the WebAssembly backend, you now need at least Node.js 23 to run and test.
+
+In Scala.js 1.17.0, the WebAssembly backend worked around some issues in Wasm engines regarding the `try_table` instruction.
+Our main blocker was the version of V8 shipped with Node.js 22.
+Now that Node.js 23 has been released with the correct behavior, we removed the workaround.
+
+### Improved internal checks after optimizations
+
+We improved "IR checking", our internal consistency checks in the linker.
+Previously, we only performed IR checking before optimizations.
+Now, we also check the IR after the optimizer if one of the following conditions hold:
+
+* you are using the Wasm backend, or
+* you are using the `bigint` encoding of `Long`s, through the setting `withESFeatures(_.withAllowBigIntsForLongs(true))`.
+
+This may surface internal bugs that we are unaware of.
+If that happens, please report an issue, as prompted by the error message.
+
+By default, IR checking is only performed during `fullLink`.
+You may disable it with the following setting:
+
+{% highlight scala %}
+Compile/fullLinkJS/scalaJSLinkerConfig ~= { _.withCheckIR(false) }
+{% endhighlight %}
+
+### Changes to the IR and linker APIs
+
+For tooling authors who directly manipulate the IR and linker APIs, there have been some breaking changes in that area.
+This is in line with our versioning policy for the linker APIs.
+
+The changes you are most likely to hit are:
+
+* We renamed `NoType` to `VoidType`, which represents the IR type `void`.
+  `void` is now generally handled more regularly.
+* `VarRef` now directly contains a `LocalName`, rather than a `LocalIdent` itself containing a `LocalName`.
+* `This` is not a separate IR node anymore; instead it is a `VarRef` with the special name `LocalName.This`.
+* `ArrayLength`, `Throw`, and a number of more obscure IR nodes have been merged into `UnaryOp`.
+* `JSLinkingInfo` was removed as a "bag of options"; it was replaced by `LinkTimeProperty` for individual properties.
+* `Transformers` does not make the distinction between "statement" and "expression" anymore.
+  This follows from handling `void` more uniformly.
+
+## Miscellaneous
+
+### New JDK APIs
+
+This release adds shell definitions for the following JDK 21 interfaces, but without any method:
+
+* `java.util.SequencedCollection`, `SequencedMap` and `SequencedSet`
+
+## Bug fixes
+
+Among others, the following bugs have been fixed in 1.18.0:
+
+* [#5085](https://github.com/scala-js/scala-js/issues/5085) `java.math.BigDecimal.valueOf(0, 9).stripTrailingZeros.scale` returns 9 instead of 0.
+* [#5069](https://github.com/scala-js/scala-js/issues/5069) Linking errors with `java.util.SequencedCollection` on JDK 21+ (considered a bug because they surfaced even in code that did not mention that new interface).
+* [#5048](https://github.com/scala-js/scala-js/issues/5048) Wasm backend fails when no modules are defined.
+* [#4947](https://github.com/scala-js/scala-js/issues/4947) Wrong optimization of `@inline` classes with several private fields of the same name in the class hierarchy.
+
+You can find the full list [on GitHub](https://github.com/scala-js/scala-js/issues?q=is%3Aissue+milestone%3Av1.18.0+is%3Aclosed).

doc/all-api.md

@@ -5,6 +5,16 @@ title: All previous versions of the Scala.js API
 
 ## All previous versions of the API
 
+### Scala.js 1.18.0
+* [1.18.0 scalajs-library]({{ site.production_url }}/api/scalajs-library/1.18.0/scala/scalajs/js/index.html)
+* [1.18.0 scalajs-test-interface]({{ site.production_url }}/api/scalajs-test-interface/1.18.0/)
+* [1.18.0 scalajs-javalib-intf]({{ site.production_url }}/api/scalajs-javalib-intf/1.18.0/)
+* [1.18.0 scalajs-ir]({{ site.production_url }}/api/scalajs-ir/1.18.0/org/scalajs/ir/index.html)
+* [1.18.0 scalajs-linker-interface]({{ site.production_url }}/api/scalajs-linker-interface/1.18.0/org/scalajs/linker/interface/index.html) ([Scala.js version]({{ site.production_url }}/api/scalajs-linker-interface-js/1.18.0/org/scalajs/linker/interface/index.html))
+* [1.18.0 scalajs-linker]({{ site.production_url }}/api/scalajs-linker/1.18.0/org/scalajs/linker/index.html) ([Scala.js version]({{ site.production_url }}/api/scalajs-linker-js/1.18.0/org/scalajs/linker/index.html))
+* [1.18.0 scalajs-test-adapter]({{ site.production_url }}/api/scalajs-sbt-test-adapter/1.18.0/org/scalajs/testing/adapter/index.html)
+* [1.18.0 sbt-scalajs]({{ site.production_url }}/api/sbt-scalajs/1.18.0/#org.scalajs.sbtplugin.package)
+
 ### Scala.js 1.17.0
 * [1.17.0 scalajs-library]({{ site.production_url }}/api/scalajs-library/1.17.0/scala/scalajs/js/index.html)
 * [1.17.0 scalajs-test-interface]({{ site.production_url }}/api/scalajs-test-interface/1.17.0/)

doc/internals/version-history.md

@@ -5,6 +5,7 @@ title: Version history
 
 ## Version history of Scala.js
 
+- [1.18.0](/news/2025/01/07/announcing-scalajs-1.18.0/)
 - [1.17.0](/news/2024/09/28/announcing-scalajs-1.17.0/)
 - [1.16.0](/news/2024/03/19/announcing-scalajs-1.16.0/)
 - [1.15.0](/news/2023/12/29/announcing-scalajs-1.15.0/)

doc/project/webassembly.md

@@ -61,7 +61,7 @@ We expect to lift that limitation in the future.
 
 ## Minimal setup
 
-The following sbt setup enables the Wasm backend and configures flags for Node.js 22.
+The following sbt setup enables the Wasm backend and configures flags for Node.js 23.
 
 {% highlight scala %}
 // Emit ES modules with the Wasm backend
@@ -71,7 +71,7 @@ scalaJSLinkerConfig := {
     .withModuleKind(ModuleKind.ESModule)  // required by the Wasm backend
 },
 
-// Configure Node.js (at least v22) to support the required Wasm features
+// Configure Node.js (at least v23) to support the required Wasm features
 jsEnv := {
   val config = NodeJSEnv.Config()
     .withArgs(List(
@@ -92,7 +92,7 @@ Here are some engines known to support enough Wasm features.
 
 ### Node.js 22
 
-As mentioned above, Node.js 22 and above requires the following flags:
+As mentioned above, Node.js 23 and above requires the following flags:
 
 * `--experimental-wasm-exnref`: required
 * `--experimental-wasm-imported-strings`: optional (good for performance)