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Manual Reference Pages  -  SCALAC (1)


scalac - Compiler for the Scala 2 language




scalac [ <options> ] <source files>


  Command line options. See OPTIONS below.
<source files>
  One or more source files to be compiled (such as MyClass.scala).


The scalac tool reads class and object definitions, written in the Scala programming language, and compiles them into bytecode class files.

By default, the compiler puts each class file in the same directory as its source file. You can specify a separate destination directory with -d (see OPTIONS, below).


The compiler has a set of standard options that are supported on the current development environment and will be supported in future releases. An additional set of non-standard options are specific to the current virtual machine implementation and are subject to change in the future. Non-standard options begin with -X.

    Standard Options

  Pass -Dproperty=value directly to the runtime system.
  Pass <flag> directly to the runtime system.
  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-separate 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.
  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 interpreter will return the default value on your system:
scala> new

  Explain type errors in more detail.
-extdirs <dirs>
  Override location of installed extensions.
  Emit warning and location for usages of features that should be imported explicitly.
  "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.
  Enable one or more language features.
  Ignore @specialize annotations.
  Do not use the boot classpath for the Scala jar files.
-nowarn Generate no warnings
  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.
  "jvm-1.5" target JVM 1.5 (deprecated),
"jvm-1.6" target JVM 1.6 (default),
"jvm-1.7" target JVM 1.7,
"jvm-1.8" target JVM 1.8,

-toolcp <path>
  Add to the runner classpath.
  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.
  Utilize the java.class.path in classpath resolution.
  Utilize the manifest in classpath resolution.
  Output messages about what the compiler is doing
  Print product version and exit.
  A text file containing compiler arguments (options and source files)

    Advanced Options

  Wrap field accessors to throw an exception on uninitialized access.
-Xdev Enable warnings for developers working on the Scala compiler
  Generate no assertions and assumptions
-Xelide-below <n>
  Calls to @elidable methods are omitted if method priority is lower than argument.
  Enable experimental extensions
  Fail the compilation if there are any warnings.
  Retain pre 2.10 behavior of less aggressive truncation of least upper bounds.
  Turn on future language features.
-Xgenerate-phase-graph <file>
  Generate the phase graphs (outputs .dot files) to
-Xlint Enable recommended additional warnings.
  Print a message when reification creates a free term.
  Print a message when reification resorts to generating a free type.
  Print a message whenever an implicit conversion is inserted.
  Show more detail on why some implicits are not applicable.
  Print a message when a reflective method call is generated.
  Custom settings for macros.
-Xmain-class <path>
  Class for manifest’s Main-Class entry (only useful with -d <jar>).
-Xmax-classfile-name <n>
  Maximum filename length for generated classes.
  Warn about constructs whose behavior may have changed since<version>.
  Do not generate static forwarders in mirror classes.
  Don’t perform exhaustivity/unreachability analysis. Also, ignore @switch annotation.
  Disable handling of \u unicode escapes
  Do not use JLine for editing.
  Load a plugin from each classpath.
  Disable plugins by name.
  Print a synopsis of loaded plugins.
  Abort if a named plugin is not loaded.
-Xpluginsdir <path>
  Path to search for plugin archives.
  Print out program after <phases> (see below).
  Log internal icode to *.icode files after<phases> (default: icode).
  Print tree positions, as offsets.
  Print tree types (debugging option).
  Display a prompt after each error (debugging option).
  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.
  Print a synopsis of compiler phases.
  Treat compiler input as Scala source for the specified version, see SI-8126.
-Xsource-reader <classname>
  Specify a custom method for reading source files.
  Don’t infer known-unsound types.
  Verify generic signatures in generated bytecode (asm backend only).
-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
  load package objects
typer the meat and potatoes: type the trees
patmat translate match expressions
  add super accessors in traits and nested classes
  add extension methods for inline classes
  serialize symbol tables
  reference/override checking, translate nested objects
  ANF pre-transform for @cps (CPS plugin)
  @cps-driven transform of selectiveanf assignments (CPS plugin)
  uncurry, translate function values to anonymous classes
  replace tail calls by jumps
  @specialized-driven class and method specialization
  this refs to outer pointers, translate patterns
  erase types, add interfaces for traits
  clean up erased inline classes
  allocate bitmaps, translate lazy vals into lazified defs
  move nested functions to top level
  move field definitions into constructors
  eliminate inner classes
mixin mixin composition
  platform-specific cleanups, generate reflective calls
  remove lambdas
icode generate portable intermediate code
  optimization: do inlining
  optimization: inline exception handlers
  optimization: eliminate uncalled closures
  optimization: optimize null and other constants
dce optimization: eliminate dead code
jvm generate JVM bytecode
  the last phase in the compiler chain
all matches all phases


  Specify the java command to be used for running the Scala code. Arguments may be specified as part of the environment variable; spaces, quotation marks, etc., will be passed directly to the shell for expansion.
  Specify JDK/JRE home directory. This directory is used to locate the java command unless JAVACMD variable set.
  Specify the options to be passed to the java command defined by JAVACMD.
With Java 1.5 (or newer) one may for example configure the memory usage of the JVM as follows: JAVA_OPTS="-Xmx512M -Xms16M -Xss16M"
With GNU Java one may configure the memory usage of the GIJ as follows: JAVA_OPTS="--mx512m --ms16m"


Compile a Scala program to the current directory
  scalac HelloWorld
Compile a Scala program to the destination directory classes
  scalac -d classes HelloWorld.scala
Compile a Scala program using a user-defined java command
  env JAVACMD=/usr/local/bin/cacao scalac -d classes HelloWorld.scala
Compile all Scala files found in the source directory src to the destination directory classes
  scalac -d classes src/*.scala


scalac returns a zero exist status if it succeeds to compile the specified input files. Non zero is returned in case of failure.


Written by Martin Odersky and other members of the Scala team.


Report bugs to


This is open-source software, available to you under a BSD-like license. See accompanying "copyright" or "LICENSE" file for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


fsc(1), scala(1), scaladoc(1), scalap(1)

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version 1.0 SCALAC (1) March 2012

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