Standard Options¶

-Dproperty=value

Pass -Dproperty=value directly to the runtime system.

-J<flag>

Pass <flag> directly to the runtime system.

-P:<plugin:opt>

Pass an option to a plugin

-X

Print a synopsis of advanced options.

-bootclasspath <path>

Override location of bootstrap class files (where to find the standard built-in classes, such as "scala.List").

-classpath <path>

Specify where to find user class files (on Unix-based systems a colon-separated list of paths, on Windows-based systems, a semicolon-separated list of paths). This does not override the built-in ("boot") search path.

The default class path is the current directory. Setting the CLASSPATH variable or using the -classpath command-line option overrides that default, so if you want to include the current directory in the search path, you must include "." in the new settings.

-d <directory|jar>

Specify where to place generated class files.

-deprecation

Emit warning and location for usages of deprecated APIs.

Available since Scala version 2.2.1

-encoding <encoding>

Specify character encoding used by source files.

The default value is platform-specific (Linux: "UTF8", Windows: "Cp1252"). Executing the following code in the Scala REPL will return the default value on your system:

scala> new java.io.InputStreamReader(System.in).getEncoding

-explaintypes

Explain type errors in more detail.

-extdirs <dirs>

Override location of installed extensions.

-feature

Emit warning and location for usages of features that should be imported explicitly.

-g:{none,source,line,vars,notailcalls}

"none" generates no debugging info,

"source" generates only the source file attribute,

"line" generates source and line number information,

"vars" generates source, line number and local variable information,

"notailcalls" generates all of the above and will not perform tail call optimization.

-help

Print a synopsis of standard options.

-javabootclasspath <path>

Override Java boot classpath.

-javaextdirs <path>

Override Java extdirs classpath.

-language:<feature>

Enable one or more language features.

-no-specialization

Ignore @specialize annotations.

-nobootcp

Do not use the boot classpath for the Scala jar files.

-nowarn

Generate no warnings

-optimise

Generates faster bytecode by applying optimisations to the program.

-print

Print program with all Scala-specific features removed.

-sourcepath <path>

Specify location(s) of source files.

-target:{jvm-1.8}

"jvm-1.8" target JVM 1.8 (default)

-toolcp <path>

Add to the runner classpath.

-unchecked

Enable detailed unchecked (erasure) warnings

Non variable type-arguments in type patterns are unchecked since they are eliminated by erasure

Available since Scala version 2.3.0

-uniqid

Uniquely tag all identifiers in debugging output.

-usejavacp

Utilize the java.class.path in classpath resolution.

-usemanifestcp

Utilize the manifest in classpath resolution.

-verbose

Output messages about what the compiler is doing

-version

Print product version and exit.

@<file>

A text file containing compiler arguments (options and source files)

Advanced Options¶

-Xcheckinit

Wrap field accessors to throw an exception on uninitialized access.

-Xdev

Enable warnings for developers working on the Scala compiler

-Xdisable-assertions

Generate no assertions and assumptions

-Xelide-below <n>

Calls to @elidable methods are omitted if method priority is lower than argument.

-Xfatal-warnings

Fail the compilation if there are any warnings.

-Xfull-lubs

Retain pre 2.10 behavior of less aggressive truncation of least upper bounds.

-Xgenerate-phase-graph <file>

Generate the phase graphs (outputs .dot files) to fileX.dot.

-Xlint

Enable recommended additional warnings.

-Xlog-free-terms

Print a message when reification creates a free term.

-Xlog-free-types

Print a message when reification resorts to generating a free type.

-Xlog-implicit-conversions

Print a message whenever an implicit conversion is inserted.

-Xlog-reflective-calls

Print a message when a reflective method call is generated.

-Xmacro-settings:<option>

Custom settings for macros.

-Xmain-class <path>

Class for manifest's Main-Class entry (only useful with -d <jar>).

-Xmigration:<version>

Warn about constructs whose behavior may have changed since<version>.

-Xno-forwarders

Do not generate static forwarders in mirror classes.

-Xno-patmat-analysis

Don't perform exhaustivity/unreachability analysis. Also, ignore @switch annotation.

-Xjline

The JLine keybindings to use: emacs/vi/off.

-Xplugin:<paths>

Load a plugin from each classpath.

-Xplugin-disable:<plugin>

Disable plugins by name.

-Xplugin-list

Print a synopsis of loaded plugins.

-Xplugin-require:<plugin>

Abort if a named plugin is not loaded.

-Xpluginsdir <path>

Path to search for plugin archives.

-Vprint:<phases>

Print out program after <phases> (see below).

-Vprint-pos

Print tree positions, as offsets.

-Vprint-types

Print tree types (debugging option).

-Xprompt

Display a prompt after each error (debugging option).

-Xresident

Compiler stays resident, files to compile are read from standard input.

-Xscript <object>

Treat the source file as a script and wrap it in a main method.

-Xshow-class <class>

Show internal representation of class.

-Xshow-object <object>

Show internal representation of object.

-Xshow-phases

Print a synopsis of compiler phases.

-Xsource:<version>

Treat compiler input as Scala source for the specified version, see scala/bug#8126.

-Xsource-reader <classname>

Specify a custom method for reading source files.

-Xstrict-inference

Don't infer known-unsound types.

-Xverify

Verify generic signatures in generated bytecode (asm backend only).

-Xxml:{coalescing}

Configure XML parsing.

"coalescing" convert PCData to Text and coalesce sibling nodes (default in 2.11).

-Y

Print a synopsis of private options.

Compilation Phases¶

parser

parse source into ASTs, perform simple desugaring

namer

resolve names, attach symbols to named trees

packageobjects

load package objects

typer

the meat and potatoes: type the trees

patmat

translate match expressions

superaccessors

add super accessors in traits and nested classes

extmethods

add extension methods for inline classes

pickler

serialize symbol tables

refchecks

reference/override checking, translate nested objects

selectiveanf

ANF pre-transform for @cps (CPS plugin)

selectivecps

@cps-driven transform of selectiveanf assignments (CPS plugin)

uncurry

uncurry, translate function values to anonymous classes

tailcalls

replace tail calls by jumps

specialize

@specialized-driven class and method specialization

explicitouter

this refs to outer pointers, translate patterns

erasure

erase types, add interfaces for traits

posterasure

clean up erased inline classes

fields

synthesize accessors and fields, including bitmaps for lazy vals

lambdalift

move nested functions to top level

constructors

move field definitions into constructors

flatten

eliminate inner classes

mixin

mixin composition

cleanup

platform-specific cleanups, generate reflective calls

delambdafy

remove lambdas

inliner

optimization: do inlining

inlineHandlers

optimization: inline exception handlers

closelim

optimization: eliminate uncalled closures

constopt

optimization: optimize null and other constants

dce

optimization: eliminate dead code

jvm

generate JVM bytecode

terminal

the last phase in the compiler chain

all

matches all phases