scalac man page

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
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 java.io.InputStreamReader(System.in).getEncoding

Explain type errors in more detail.
-extdirs <dirs>
Override location of installed extensions.

"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.

Print a synopsis of standard options.
-javabootclasspath <path>
Override Java boot classpath.
-javaextdirs <path>
Override Java extdirs classpath.
Ignore @specialize annotations.
Do not use the boot classpath for the Scala jar files.
Generate no warnings
Generates faster bytecode by applying optimisations to the program.
Print program with all Scala-specific features removed.
-sourcepath <path>
Specify location(s) of source files.

Specify which backend to use (jvm-1.5,msil).

The default value is "jvm-1.5" (was "jvm-1.4" up to Scala version 2.6.1).

-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

Uniquely tag all identifiers in debugging output.
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

-Xassem-extdirs <dirs>
(Requires -target:msil) List of directories containing assemblies. default:lib.
-Xassem-name <file>
(Requires -target:msil) Name of the output assembly.
-Xassem-path <path>
(Requires -target:msil) List of assemblies referenced by the program.
Warn upon selection of nullable reference
Wrap field accessors to throw an exception on uninitialized access.
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.
Turn on future language features.
-Xgenerate-phase-graph <file>
Generate the phase graphs (outputs .dot files) to fileX.dot.
Enable recommended additional warnings.
Show more detail on why some implicits are not applicable.
-Xmax-classfile-name <n>
Maximum filename length for generated classes.
Warn about constructs whose behavior may have changed between 2.7 and 2.8.
Do not generate static forwarders in mirror classes.
Disable handling of \u unicode escapes
Do not use JLine for editing.
Load a plugin from a file
Disable a plugin
Print a synopsis of loaded plugins
Abort unless the given plugin(s) are available
-Xpluginsdir <path>
Path to search compiler plugins.
Print out program after <phases> (see below).
Log internal icode to *.icode files.
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.
-Xsource-reader <classname>
Specify a custom method for reading source files.
-Xsourcedir <path>
(Requires -target:msil) Mirror source folder structure in output directory..
Verify generic signatures in generated bytecode.
Print a synopsis of private options.

Compilation Phases

initializing compiler
parse source files
create symbols
name and type analysis
reference checking
uncurry function types and applications
lambda lifter
represent types as values
add accessors for constructor arguments
make links from inner classes to enclosing one explicit
add explicit constructor for each class
add tail-calls
perform whole program analysis
add one interface per class
expand mixins by code copying
makes boxing explicit
type eraser
generate icode
enable code generation
compilation terminated
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

Exit Status

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.

Reporting Bugs

Report bugs to https://issues.scala-lang.org/.

See Also

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

Referenced By

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

Explore man page connections for scalac(1).

version 1.0 March 2012