You can setup auto-update of Scala plugin Nightly builds in IntelliJ IDEA.
Simply select desired update channel from a drop-down menu at "Updates" tab in Scala plugin settings page.

• SCL-10295 Overload resolution problem

• SCL-10295 Overload resolution problem

• SCL-10311 false "Wrong number of arguments for extractor" highlighting
• SCL-9868 "Move statements right and left" for Scala too (not just java/html)
• SCL-9977 ui lockup in very small file
• SCL-10306 wrong type inference for argument patterns if extractor has implicit parameter

• SCL-10301 can't evaluate method call work if qualifier has a same name as implicitly imported package
• SCL-10287 Wrong RedundantNewCaseClass intention invokation in case of companion object with defined apply method
• SCL-10285 Duplication in description of RedundantNewCaseClass inspection and incorrect intension_action message
• SCL-10293 New intention to regenerate type annotation for var/val/def
• SCL-10289 Wrong RedundantNewCaseClass inspection call in case of apply with implicit parameter
• SCL-10295 Overload resolution problem

• SCL-9840 Collection inspection: convert map.get(k).get to map(k)
• SCL-10257 Ability to specify working directory for SBT task run configuration

• SCL-9844 Inspection: redundant `new` keyword in case class instantiation
• SCL-10244 Imported library classes are parsed incorrectly which lead to weird import errors

• SCL-10245 Scala Compile Server idle timeout won't stick
• SCL-10233 When selecting menu option "Build/Rebuild Project", compilation aborts with error "Error:scalac: Error: org.jetbrains.jps.incremental.scala.remote.ServerException"

• SCL-9841 Collection inspection: convert map.find(_ == k).map(_._2) to map(k)
• SCL-10240 Super Method tool doesn't work with overridden methods of self references

• SCL-10037 good code is red (existential types)

• SCL-10161 Cannot close project because of blocked thread

• SCL-9619 Type mismatch error for java annotation with element called 'lazy'

• SCL-10103 Breakpoints in trait methods don't work since Scala uses default methods at the bytecode level

• SCL-10105 Freeze on importing SBT Project

• SCL-9514 Move a class with companion object causes "File already exists problem"
• SCL-5456 Refactoring a Scala file with class and companion object fails

• SCL-10109 Internal Server error in default Play2 template

• SCL-6619 case classes without parameters are removed from Scala 2.11
• SCL-4988 Parameter Info stops working with functions when using import renames

• SCL-9861 Inspection: unnecessary partial function definition

• SCL-10027 Good code red: error highlight in case class copy caused by existence of same-named, but unrelated method
• SCL-9578 No error when var implements val

• SCL-10071 Deadlock
• SCL-3781 Bad code is green: parameterized class without type arguments

• SCL-10036 Breakpoints not working in scala async blocks in Scala 2.10
• SCL-9942 Wrong error highlighting because of object rename
• SCL-8947 Create New Scala Class - wrong error "This is not a valid Scala qualified name"

• SCL-9161 The verb "re-format" should be written without a hyphen

• SCL-10039 Setting Scala compiler incrementality type to SBT breaks Java projects
• SCL-7089 Value tooltip does not show up when debugging Scala
• SCL-10042 'Type annotation required' inspection marks constructor as missing return type annotation
• SCL-9395 Scala Console run config broken IDEA 15.0 - java.lang.ClassNotFoundException: @vm_params

• SCL-9116 Option.contains inspection is invalid on Scala 2.10 but still suggested
• SCL-9975 Additional compiler options change takes effect only after rebooting compile server twice
• SCL-9898 Suggest types based on variable name
• SCL-3490 override def autocomplete
• SCL-9306 Good code red: implicitly conversions from functions to functions

• SCL-10006 Incorrect type inference

• SCL-8858 Usage of none monospace font in error message.
• SCL-9920 Erroneous pattern matching warning

• SCL-9916 Inspection pass never completes for the specific file
• SCL-9915 Scala Single Abstract Method (SAM) with by-name argument compilation error: identifier expected but '=>' found.

• SCL-9938 Remove error highlighting from type element in case of type mismatch

• SCL-9473 Methods on a method argument are not found any longer if argument type contains refinement
• SCL-8119 Scala: Breeze operations return 'Nothing' in editor, while compilation works fine.

• SCL-9456 Scala return type error highlighting confusing in a try/catch block

• SCL-9760 Don't suggest length-related collection inspections for Array

• SCL-2022 Autocompletion: suggest nearby references first
• SCL-6617 Feature request: sort completions by scope
• SCL-8408 Weird priorities in the autocompletion cause great pain with quick typing

• SCL-9832 Do not warn about empty-parens for getters in ScalaJS facades

• SCL-9372 Code with eq is missing parenthesis
• SCL-9375 Array initializers are not translated correctly, wrong type ascription

• SCL-9682 "anonymous function can be turned into a method value" is overeager

• SCL-9346 Wrong warning 'Comparing unrelated types' for overloaded == and != operators

• SCL-9838 Wrong "comparing unrelated types" with a type alias for a Float
• SCL-9820 Incorrect inspection "Anonymous function convertible to a method value"

• SCL-9865 Injection API - It's impossible to extend annotated class type

• SCL-9361 Inspection: Hash code uses a var

• SCL-4289 Java calling Scala, bad code green when constructing a trait

• SCL-9863 Code coloring is broken (deprecated attributes usage)
• SCL-4289 Java calling Scala, bad code green when constructing a trait

• SCL-9715 Redundant conversion inspection is unstable
• SCL-9716 Inspection: redundant `val` modifier in case class

• SCL-9774 Wrong warning "Field in DelayedInit is likely to be null" for lazy vals
• SCL-9717 IntelliJ code inspector not using ScalaStyle latest version?
• SCL-9764 IDE hangs when writing a for comprehension with an underscore
• SCL-9699 Scala "Output path is shared between modules" error with new IDEA 16 module structure

• SCL-9774 Wrong warning "Field in DelayedInit is likely to be null" for lazy vals
• SCL-9717 IntelliJ code inspector not using ScalaStyle latest version?
• SCL-9699 Scala "Output path is shared between modules" error with new IDEA 16 module structure

• SCL-9712 Inspection: use partial function instead of explicit pattern matching

• SCL-9757 FREQUENT FREEZING AND LOSS OF DATA

• SCL-9742 Play is not working in 2.0.228.6

• SCL-9661 Intellij idea 15 not infering scala types correctly in Java 1.8 project

• SCL-8232 Incorrect syntax error when supplying id function to traverse method

• SCL-9505 Some breakpoints in lambdas are never hit

• SCL-9640 Scala plugin reports errors when source file located outside the source root is opened
• SCL-9412 Bad return type in method reference when calling Stream.map with constructor of Scala class
• SCL-9627 False highlighted error: type mismatch on a custom AnyVal class assignment in an OptionAnyVal

• SCL-9261 Good code is red: Slick
• SCL-9429 Scala plugin doesn't support pattern matching on case classes with more than 22 parameters

• SCL-8514 sbt plugin does not honor SBT_OPTS environment variable

• SCL-9597 Importing/opening a Gradle Scala project incorrectly configures the Scala compiler encoding setting

• SCL-9434 Arrays are translated to incorrect, uncompilable code

• SCL-9545 Parentheses wrongly removed from expression on simplify boolean ...
• SCL-9574 .map(_ == "").getOrElse(true) should be .forall(_ == "")

• SCL-9542 Introduce var poor type deduction

• SCL-9475 error opening sbt project spoiwo: ;' expected but 'lazy' found.

• SCL-9446 SyntheticMembersInjector injectFunctions doesn't override abstract methods

• SCL-9535 ClassCastException since IDEA 15 upgrade

• SCL-9445 SyntheticMembersInjector doesn't inject case class properly
• SCL-9457 some types in decompiled classes from 2.12 M3 contains `<no symbol>`.`<root>` prefix

• SCL-9504 Invalid range of TODO item
• SCL-9501 Fatal Error reporter does not work with Scala plugin

• SCL-9480 Cannot disable the inspection `method XXX is never used` using a source code comment
• SCL-9460 Type error highlighted on a valid array of anonymous functions

• SCL-9234 .idea/scala_compiler.xml gets corrupted during SBT refresh

• SCL-9039 Debugging inside `async` block of code

• SCL-8970 no highlighting for extractor pattern in patten match

• SCL-9455 Wrong inspection of DelayedInit for App trait

• SCL-9453 Error running play 2 project
• SCL-9419 Highlighting error for `import scala.scalajs.js.|`

• SCL-9426 Good code red - Regression in v15
• SCL-9417 Auto converted code red
• SCL-9433 Good code red - Another v15 regression

• SCL-9420 Good code red with Monocle @Lenses - Regression in v15
• SCL-9409 Good code red - Regression in v15

• SCL-9410 Wrong error highlight in IDEA 15

• SCL-8115 Scala pattern match tuple-crushing mechanism not respected by the type checker
• SCL-9394 Scala good code red in v15 only
• SCL-3531 Bad code not flagged: var field used as static id pattern
• SCL-9385 Issue an hint for `0 to bla - 1` to be `0 until bla` instead in Scala
• SCL-8160 Highlighting error for Enumeration
• SCL-9400 IntelliJ IDEA 15 Scala plugin 2.0.0 not recognizing a Scala class
• SCL-8970 no highlighting for extractor pattern in patten match

• SCL-9383 Please return back possibility to update vals in debugger
• SCL-9156 Reference searchers from Scala plugin are slow
• SCL-8240 Good code marked as bad: mixin types with path dependent types
• SCL-9020 Trying to infer type in ??? for Scala project halts IntelliJ
• SCL-9388 Scala Plugin for Intellij doesn't resolve SBT dependecies specified w/ Major Version Syntax
• SCL-9390 Error checking suddenly disabled / stuck for a fragment of the code

• SCL-8246 Good code marked red : type Self + template, tested on 1.3.2

• SCL-9340 Debugger open incorrect file if breakpont reached
• SCL-9343 IntelliJ highlights valid code as error in Scala Plugin 1.9.265

• SCL-9340 Debugger open incorrect file if breakpont reached
• SCL-9343 IntelliJ highlights valid code as error in Scala Plugin 1.9.265

• SCL-9340 Debugger open incorrect file if breakpont reached
• SCL-9343 IntelliJ highlights valid code as error in Scala Plugin 1.9.265

• SCL-9354 Scala plugin broken by Scala compiler sources

• SCL-9312 OutOfMemoryError when import/refresh large sbt project

• SCL-9239 A lot of sub-projects in Multi-project build
• SCL-9287 Missing specs2 and junit libraries in the dependencies of a new Play project
• SCL-9309 No warning for duplicate aliases
• SCL-9263 Value classes are not highlighted
• SCL-9317 Mark expanded macro applications
• SCL-2066 Formatter incorrectly indents braces of methods and other blocks if they are configured to be on a new line.
• SCL-8959 Change "working directory" of scala compiler to match project home
• SCL-9272 Labeled objects do not work in "Evaluate expression" if "Scala" is selected
• SCL-9124 Scala plugin shows too many duplicated classes in inheritors dialog
• SCL-9294 With Scala plugin enabled, com.intellij.debugger.NoDataException is thrown while debugging
• SCL-2507 default parameters should drive type inference
• SCL-9273 Hierarchy, Go to implementation, and implementation gutter icons are broken
• SCL-9290 NPE on running Play
• SCL-7178 Provide better error message, when two type have the same name
• SCL-7948 When accessing Scala's Tuple2 elements, ._1 and ._2 are highlighted as invalid syntax. I need to use ._1() and ._2().
• SCL-8195 An ability to mark some imports as used (so they are not removed upon reformat)

• SCL-9235 Incorrect "Java accessor method called as empty-paren" with Java 8 Stream API
• SCL-8167 Perform eviction for dependencies when importing project

• SCL-8800 Code highlighting is totally broken for simulacrum

• SCL-9270 possibility to create and use variables in evaluate expression
• SCL-9240 Good code yellow: "Useless expression" flagged incorrectly
• SCL-9179 Make 'Enable optimize imports automatically' command not a top-most one

• SCL-8933 Good code red: Wrong type inference in for comprehension (inferes to Nothing)

• SCL-9252 add quickfix for "Type annotation required" inspection

• SCL-8866 Syntax highlighting issue with Java 8

• SCL-9018 EAP Debugger do not respect breakpoints in tests
• SCL-9141 Debugger jumps around in match statement
• SCL-9049 Scaladoc generates stub with return also when return type is Unit
• SCL-9031 Inspection for mapping to unit values fires when mapping to function returning unit
• SCL-9046 Play Framework, Twirl: Syntax highlighting error.
• SCL-9051 Cannot rename variable on twirl parameters
• SCL-9045 Play Framework, Twirl: Syntax highlighting error. Assigning an expression to an html attribute.
• SCL-9230 debugger trees: label don't changes from "Collecting data..." for vars
• SCL-8965 SBT import is still broken (two months already)
• SCL-7909 incorrect "unnecessary parentheses" hint in scala
• SCL-3520 Honour "skip simple getters" setting
• SCL-9191 Throwable on new Play project creation
• SCL-9010 "Your IDEA is outdated to use with Scala plugin" message with reference to build already in use
• SCL-9192 Expression of type BigDecimal doesn't conform to expected type BigDecimal

• SCL-3520 Honour "skip simple getters" setting

• SCL-9141 Debugger jumps around in match statement
• SCL-7909 incorrect "unnecessary parentheses" hint in scala

• SCL-9175 ScalaDoc parsing fails with code block containing JSON
• SCL-9157 Faster file type detection

• SCL-3151 widen selection should include XML attribute text, then attribute text with quotation marks
• SCL-9158 Scala getClassesByName takes too much in a project that has no Scala
• SCL-4953 parameter info doesn't find apply method of compound type
• SCL-5437 Inspection idea: warn when selecting a 'val' from a DelayedInit subclass (e.g. App)

• SCL-7431 Play template variables that generate full HTML attributes marked as errors
• SCL-9159 Inefficient ScClsStubBuilder
• SCL-8966 Scala worksheet doesn't work with backticks

• SCL-4484 Mark "then" as deprecated

• SCL-9146 ScalaJS React <. broken in Intellij 15 EAP

• SCL-9147 Stuck in an infinite loop when trying to import a project

• SCL-8989 Unable to track types through Scala Graph nodes
• SCL-8486 Copy+paste loses formatting JS code in *.scala.html template
• SCL-6738 Javascript formatting broken in Play Framework Scala Templates

• SCL-9129 some files from scala library are decompiled as java in scala 2.12.0-M2
• SCL-9135 Generate property generates wrong name for a setter

• SCL-9121 Import statements in worksheet become duplicated in output
• SCL-3603 good code red
• SCL-9124 Scala plugin shows too many duplicated classes in inheritors dialog

• SCL-5099 Pattern variables in field declarations are highlighted as fields

• SCL-9100 Create run configuration for Play pfoject
• SCL-9102 Open in browser after compilation is not working

• SCL-9044 SBT 0.13.9 not working with Intellij

• SCL-9046 Play Framework, Twirl: Syntax highlighting error.
• SCL-9049 Scaladoc generates stub with return also when return type is Unit
• SCL-9051 Cannot rename variable on twirl parameters

• SCL-9015 Very usual situation, when class can't be resolved in evaluate expression
• SCL-9019 A jar dependency (httpcore 4.0.1) keeps being "detached" from its "library" in the IDEA project every time the Gradle project is refreshed

• SCL-8999 Feature needed for call-by-name value parameter error
• SCL-9006 IAE at ScTypePsiTypeBridge$class.create() on Copy of Java type specification with additional bound

• SCL-9004 Interpolation completion is not working for function parameter
• SCL-8944 Update ScalaStyle Version

• SCL-8875 Good code red: weird type inference issues

• SCL-8995 Good Code Red: Cannot resolve method Xxx.Unapply where the unapply method is synthetic but overrides an abstract unapply method
• SCL-8932 Invalid Replace with Option application when body is a function call

• SCL-8579 SBT import does not respect JDK deduced by sbt-structure 1.4.15

• SCL-8965 SBT import is still broken (two months already)

• SCL-8631 Type error not shown when type tooltip is enabled

• SCL-8162 Support Kind Projector

• SCL-8890 inspection access to first/last element by index
• SCL-8917 Breakpoints in lambda sometimes trigger in a different source file
• SCL-8921 Don't truncate the logger message in org.jetbrains.jps.cmdline.BuildMain (line 405?)

• SCL-8935 NPE at autocompletion

• SCL-8920 New SAM inspection doesn't catch Callable
• SCL-5367 Good code shows as red: Using Value Types from Java

• SCL-8157 Good code red: calling apply in implicitly converted object

• SCL-8908 Plugin version lost if switching update channel

• SCL-8793 Good code red: function resolves to a completely unrelated library
• SCL-7170 Good code red: underscore after a by-name parameter
• SCL-7885 Java editor doesn't recognize all exceptions marked with @throws in Scala code

• SCL-4625 Spurious error accessing a protected method within a java class

• IDEA-142373 JavaTestFinders escape

• SCL-8863 Good code red: @uncheckedVariance annotation
• SCL-6140 Support Scala 2.11 SAM

• SCL-8803 Error highlighted when using multiple constructors for covariant generics
• SCL-8632 Import quick fix menu automatically open Exclude sub-menu

• SCL-8760 Wrong documentation is shown in editor
• SCL-8727 Play 2.4 RC2 Routes error highlighted (routesGenerator)

• SCL-8600 <Label>_DebugLabel variables not accessible in Scala debugger

• SCL-8568 Disable "Name boolean parameters" for single argument methods

• SCL-8626 Noinspection ScalaFileName is not working
• SCL-8659 @Nullable parameter annotation in Scala ignored in Java
• SCL-8704 Wrong "Convert match statement to pattern matching anonymous function" suggestion
• SCL-8623 Introduce variable: wrong place is chosen in for statement