path: root/tools/build/v2/doc/src/reference.xml

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<!DOCTYPE chapter PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
  "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd"
[
<!ENTITY toolset_ops "<optional><replaceable>version</replaceable></optional> : <optional><replaceable>c++-compile-command</replaceable></optional> : <optional><replaceable>compiler options</replaceable></optional>">
<!ENTITY option_list_intro "<para>The following options can be provided, using <literal>&lt;<replaceable>option-name</replaceable>&gt;<replaceable>option-value</replaceable></literal> syntax:</para>">
<!ENTITY using_repeation "<para>This statement may be repeated several times, if you want to configure several versions of the compiler.</para>">
]>

<chapter id="bbv2.reference"
         xmlns:xi="http://www.w3.org/2001/XInclude">
  <title>Reference</title>

  <section id="bbv2.reference.general">
    <title>General information</title>

    <section id="bbv2.reference.init">
      <title>Initialization</title>

      <para>bjam's first job upon startup is to load the Jam code that
        implements the build system. To do this, it searches for a file
        called <filename>boost-build.jam</filename>, first in the invocation directory, then
        in its parent and so forth up to the filesystem root, and finally
        in the directories specified by the environment variable
        BOOST_BUILD_PATH. When found, the file is interpreted, and should
        specify the build system location by calling the boost-build
        rule:</para>

<programlisting>
rule boost-build ( location ? )
</programlisting>

      <para>
        If location is a relative path, it is treated as relative to
        the directory of <filename>boost-build.jam</filename>. The directory specified by
        that location and the directories in BOOST_BUILD_PATH are then searched for
        a file called <filename>bootstrap.jam</filename>, which is expected to
        bootstrap the build system. This arrangement allows the build
        system to work without any command-line or environment variable
        settings. For example, if the build system files were located in a
        directory "build-system/" at your project root, you might place a
        <filename>boost-build.jam</filename> at the project root containing:

<programlisting>
boost-build build-system ;
</programlisting>

        In this case, running <command>b2</command> anywhere in the project tree will
        automatically find the build system.</para>

      <para>The default <filename>bootstrap.jam</filename>, after loading some standard
        definitions, loads two <filename>site-config.jam</filename> and <filename>user-config.jam</filename>.</para>

    </section>

  </section>

  <section id="bbv2.reference.rules">
    <title>Builtin rules</title>

    <para>This section contains the list of all rules that
    can be used in Jamfile&#x2014;both rules that define new
    targets and auxiliary rules.</para>

    <variablelist>
      <varlistentry>
        <term><literal>exe</literal></term>

        <listitem><para>Creates an executable file. See
        <xref linkend="bbv2.tasks.programs"/>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>lib</literal></term>

        <listitem><para>Creates an library file. See
        <xref linkend="bbv2.tasks.libraries"/>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>install</literal></term>

        <listitem><para>Installs built targets and other files. See
        <xref linkend="bbv2.tasks.installing"/>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>alias</literal></term>

        <listitem><para>Creates an alias for other targets. See
        <xref linkend="bbv2.tasks.alias"/>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>unit-test</literal></term>

        <listitem><para>Creates an executable that will be automatically run. See
        <xref linkend="bbv2.builtins.testing"/>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>compile</literal></term>
        <term><literal>compile-fail</literal></term>
        <term><literal>link</literal></term>
        <term><literal>link-fail</literal></term>
        <term><literal>run</literal></term>
        <term><literal>run-fail</literal></term>

        <listitem><para>Specialized rules for testing. See
        <xref linkend="bbv2.builtins.testing"/>.</para></listitem>
      </varlistentry>


      <varlistentry>
        <term><literal>obj</literal></term>

        <listitem><para>Creates an object file. Useful when a single source
        file must be compiled with special properties.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>preprocessed</literal></term>
        <indexterm><primary>preprocessed</primary></indexterm>

        <listitem><para>Creates an preprocessed source file. The arguments follow the
        <link linkend="bbv2.main-target-rule-syntax">common syntax</link>.</para></listitem>
      </varlistentry>

      <varlistentry id="bbv2.reference.rules.glob">
        <term><literal>glob</literal></term>

        <listitem><para>The <code>glob</code> rule takes a list shell pattern
        and returns the list of files in the project's source directory that
        match the pattern. For example:
        <programlisting>
lib tools : [ glob *.cpp ] ;
        </programlisting>
        It is possible to also pass a second argument&#x2014;the list of
        exclude patterns. The result will then include the list of
        files patching any of include patterns, and not matching any
        of the exclude patterns. For example:
        <programlisting>
lib tools : [ glob *.cpp : file_to_exclude.cpp bad*.cpp ] ;
        </programlisting>
        </para></listitem>
      </varlistentry>

      <varlistentry id="bbv2.reference.glob-tree">
        <indexterm><primary>glob-tree</primary></indexterm>
        <term><literal>glob-tree</literal></term>

        <listitem><para>The <code>glob-tree</code> is similar to the
        <code>glob</code> except that it operates recursively from
        the directory of the containing Jamfile. For example:
        <programlisting>
ECHO [ glob-tree *.cpp : .svn ] ;
        </programlisting>
        will print the names of all C++ files in your project. The
        <literal>.svn</literal> exclude pattern prevents the
        <code>glob-tree</code> rule from entering administrative
        directories of the Subversion version control system.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>project</literal></term>

        <listitem><para>Declares project id and attributes, including
        project requirements. See <xref linkend="bbv2.overview.projects"/>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>use-project</literal></term>

        <listitem><para>Assigns a symbolic project ID to a project at
        a given path. This rule must be better documented!
        </para></listitem>
      </varlistentry>

      <varlistentry id="bbv2.reference.rules.explicit">
        <term><literal>explicit</literal></term>

        <listitem><para>The <literal>explicit</literal> rule takes a single
        parameter&#x2014;a list of target names. The named targets will
        be marked explicit, and will be built only if they are explicitly
        requested on the command line, or if their dependents are built.
        Compare this to ordinary targets, that are built implicitly when
        their containing project is built.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>always</literal></term>
        <indexterm><primary>always building a metatarget</primary></indexterm>

        <listitem><para>The <literal>always</literal> funciton takes a single
        parameter&#x2014;a list of metatarget names. The top-level targets produced
        by the named metatargets will be always considered out of date. Consider this example:
        </para>
<programlisting>
exe hello : hello.cpp ;
exe bye : bye.cpp ;
always hello ;
</programlisting>
        <para>If a build of <filename>hello</filename> is requested, then the binary will
        always be relinked. The object files will not be recompiled, though. Note that if
        a build of <filename>hello</filename> is not requested, for example you specify just
        <filename>bye</filename> on the command line, <filename>hello</filename> will not
        be relinked.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>constant</literal></term>

        <listitem><para>Sets project-wide constant. Takes two
        parameters: variable name and a value and makes the specified
        variable name accessible in this Jamfile and any child Jamfiles.
        For example:
        <programlisting>
constant VERSION : 1.34.0 ;
        </programlisting>
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>path-constant</literal></term>

        <listitem><para>Same as <literal>constant</literal> except that
        the value is treated as path relative to Jamfile location. For example,
        if <command>b2</command> is invoked in the current directory,
        and Jamfile in <filename>helper</filename> subdirectory has:
        <programlisting>
path-constant DATA : data/a.txt ;
        </programlisting>
        then the variable <varname>DATA</varname> will be set to
        <literal>helper/data/a.txt</literal>, and if <command>b2</command>
        is invoked from the <filename>helper</filename> directory, then
        the variable <varname>DATA</varname> will be set to
        <literal>data/a.txt</literal>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>build-project</literal></term>

        <listitem><para>Cause some other project to be built. This rule
        takes a single parameter&#x2014;a directory name relative to
        the containing Jamfile. When the containing Jamfile is built,
        the project located at that directory will be built as well.
        At the moment, the parameter to this rule should be a directory
        name. Project ID or general target references are not allowed.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>test-suite</literal></term>

        <listitem><para>This rule is deprecated and equivalent to
        <code>alias</code>.</para></listitem>
      </varlistentry>

    </variablelist>

  </section>

  <section id="bbv2.overview.builtins.features">
    <title>Builtin features</title>

    <para>This section documents the features that are built-in into
    Boost.Build. For features with a fixed set of values, that set is
    provided, with the default value listed first.</para>

    <indexterm><primary>features</primary><secondary>builtin</secondary></indexterm>

    <variablelist>
      <varlistentry><term><literal>variant</literal></term>
        <indexterm><primary>variant</primary></indexterm>

        <listitem>
          <para>
            A feature combining several low-level features, making it easy to
            request common build configurations.
          </para>

          <para>
            <emphasis role="bold">Allowed values:</emphasis>
            <literal>debug</literal>, <literal>release</literal>,
            <literal>profile</literal>.
          </para>

          <para>
            The value <literal>debug</literal> expands to
          </para>

<programlisting>
&lt;optimization&gt;off &lt;debug-symbols&gt;on &lt;inlining&gt;off &lt;runtime-debugging&gt;on
</programlisting>

          <para>
            The value <literal>release</literal> expands to
          </para>

<programlisting>
&lt;optimization&gt;speed &lt;debug-symbols&gt;off &lt;inlining&gt;full &lt;runtime-debugging&gt;off
</programlisting>

          <para>
            The value <literal>profile</literal> expands to the same as
            <literal>release</literal>, plus:
          </para>

<programlisting>
&lt;profiling&gt;on &lt;debug-symbols&gt;on
</programlisting>

          <para>
            Users can define their own build variants using the
            <code>variant</code> rule from the <code>common</code> module.
          </para>

          <para>
            <emphasis role="bold">Note:</emphasis> Runtime debugging is on in
            debug builds to suit the expectations of people used to various
            IDEs.
            <!-- Define "runtime debugging". Why will those people expect it to
            be on in debug builds? -->
          </para>
        </listitem>
      </varlistentry>

      <varlistentry id="bbv2.overview.builtins.features.link">
        <term><literal>link</literal></term>
        <indexterm><primary>link</primary></indexterm>

        <listitem>

          <para><emphasis role="bold">Allowed values:</emphasis> <literal>shared</literal>,
            <literal>static</literal></para>

          <simpara>
            A feature controling how libraries are built.
          </simpara>

        </listitem>
      </varlistentry>

      <varlistentry id="bbv2.overview.builtins.features.runtime-link">
        <indexterm><primary>runtime linking</primary></indexterm>
        <term><literal>runtime-link</literal></term>

        <listitem>
          <para><emphasis role="bold">Allowed values:</emphasis> <literal>shared</literal>,
            <literal>static</literal></para>

          <simpara>
            Controls if a static or shared C/C++ runtime should be used. There
            are some restrictions how this feature can be used, for example
            on some compilers an application using static runtime should
            not use shared libraries at all, and on some compilers,
            mixing static and shared runtime requires extreme care.  Check
            your compiler documentation for more details.
          </simpara>

        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>threading</literal></term>
        <indexterm><primary>threading</primary></indexterm>

        <listitem>

          <para><emphasis role="bold">Allowed values:</emphasis> <literal>single</literal>,
            <literal>multi</literal></para>

          <simpara>
            Controls if the project should be built in multi-threaded mode.  This feature does not
            necessary change code generation in the compiler, but it causes the compiler to link
            to additional or different runtime libraries, and define additional preprocessor 
            symbols (for example, <code>_MT</code> on Windows and <code>_REENTRANT</code> on Linux). 
            How those symbols affect the compiled code depends on the code itself.
          </simpara>

        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>source</literal></term>
        <indexterm><primary>source</primary></indexterm>

        <listitem>
          <simpara>
            The <code>&lt;source&gt;X</code> feature has the same effect on
            building a target as putting X in the list of sources. It is useful
            when you want to add the same source to all targets in the project
            (you can put &lt;source&gt; in requirements) or to conditionally
            include a source (using conditional requirements, see <xref linkend=
            "bbv2.tutorial.conditions"/>). See also the <code>&lt;library&gt;
            </code> feature.
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>library</literal></term>
        <indexterm><primary>library</primary></indexterm>

        <listitem>
          <simpara>
            This feature is almost equivalent to the <code>&lt;source&gt;</code>
            feature, except that it takes effect only for linking. When you want
            to link all targets in a Jamfile to certain library, the
            <code>&lt;library&gt;</code> feature is preferred over
            <code>&lt;source&gt;X</code>&mdash;the latter will add the library to
            all targets, even those that have nothing to do with libraries.
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry><term><anchor id="bbv2.builtin.features.dependency"/>
          <literal>dependency</literal></term>
          <indexterm><primary>dependency</primary></indexterm>

        <listitem>
          <simpara>
            Introduces a dependency on the target named by the value of this
            feature (so it will be brought up-to-date whenever the target being
            declared is). The dependency is not used in any other way.

            <!--
            ====================================================================
            An example and a motivation is needed here. Below is some commented
            out content that used to be here but did not make any sense and
            seems to have been left unfinished in some previous revision. Should
            be fixed and this whole feature should be retested and fixed as
            needed.
            ====================================================================
            For example, in application with plugins, the plugins are not used
            when linking the application, application might have a dependency on
            its plugins, even though

            and
            adds its usage requirements to the build properties
            of the target being declared.

            The primary use case is when you want
            the usage requirements (such as <code>#include</code> paths) of some
            library to be applied, but do not want to link to it.

            It is hard to picture why anyone would want to do that. Please flesh
            out this motivation.
            ====================================================================
            -->
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry><term><anchor id="bbv2.builtin.features.implicit-dependency"/>
        <literal>implicit-dependency</literal></term>
        <indexterm><primary>implicit-dependency</primary></indexterm>

        <listitem>
          <simpara>
            Indicates that the target named by the value of this feature
            may produce files that are included by the sources of the
            target being declared.  See <xref linkend="bbv2.reference.generated_headers"/>
            for more information.
          </simpara>
        </listitem>
      </varlistentry>


      <varlistentry><term><anchor id="bbv2.builtin.features.use"/>
          <literal>use</literal></term>
          <indexterm><primary>use</primary></indexterm>

        <listitem>
          <simpara>
            Introduces a dependency on the target named by the value of this
            feature (so it will be brought up-to-date whenever the target being
            declared is), and adds its usage requirements to the build
            properties
            <!-- Do you really mean "to the requirements?" -->
            of the target being declared. The dependency is not used in any
            other way. The primary use case is when you want the usage
            requirements (such as <code>#include</code> paths) of some library
            to be applied, but do not want to link to it.
            <!-- It is hard to picture why anyone would want to do that. Please
            flesh out this motivation. -->
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><anchor id="bbv2.reference.features.dll-path"/>
        <literal>dll-path</literal></term>
        <indexterm><primary>dll-path</primary></indexterm>

        <listitem>
          <simpara>
            Specify an additional directory where the system should
            look for shared libraries when the executable or shared
            library is run. This feature only affects Unix
            compilers. Plase see <xref linkend="bbv2.faq.dll-path"/>
            in <xref linkend="bbv2.faq"/> for details.
          </simpara>
        </listitem></varlistentry>

      <varlistentry>
        <term><literal>hardcode-dll-paths</literal></term>
        <indexterm><primary>hardcode-dll-paths</primary></indexterm>

        <listitem>
          <simpara>
            Controls automatic generation of dll-path properties.
          </simpara>

          <para><emphasis role="bold">Allowed values:</emphasis>
            <literal>true</literal>, <literal>false</literal>.  This property is
            specific to Unix systems. If an executable is built with
            <code>&lt;hardcode-dll-paths&gt;true</code>, the generated binary
            will contain the list of all the paths to the used shared libraries.
            As the result, the executable can be run without changing system
            paths to shared libraries or installing the libraries to system
            paths. This <!-- you need an antecedent.  This _what_? --> is very
            convenient during development. Plase see the <link linkend=
            "bbv2.faq.dll-path">FAQ entry</link> for details. Note that on Mac
            OSX, the paths are unconditionally hardcoded by the linker, and it
            is not possible to disable that behaviour.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>cflags</literal></term>
        <term><literal>cxxflags</literal></term>
        <term><literal>linkflags</literal></term>

        <listitem>
          <simpara>
            The value of those features is passed without modification to the
            corresponding tools. For <code>cflags</code> that is both the C and
            C++ compilers, for <code>cxxflags</code> that is the C++ compiler
            and for <code>linkflags</code> that is the linker. The features are
            handy when you are trying to do something special that cannot be
            achieved by a higher-level feature in Boost.Build.
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>include</literal></term>
        <indexterm><primary>include</primary></indexterm>

        <listitem>
          <simpara>
            Specifies an additional include path that is to be passed to C and
            C++ compilers.
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><literal>define</literal></term>
        <indexterm><primary>define</primary></indexterm>

        <listitem>
          <simpara>
            Specifies an preprocessor symbol that should be defined on the command
            line. You may either specify just the symbol, which will be defined
            without any value, or both the symbol and the value, separated by
            equal sign.
          </simpara>
        </listitem>
      </varlistentry>


      <varlistentry><term><literal>warnings</literal></term>
        <listitem>
          <simpara>
            The <code>&lt;warnings&gt;</code> feature controls the warning level
            of compilers. It has the following values:
            <itemizedlist>
              <listitem><para><code>off</code> - disables all warnings.</para></listitem>
              <listitem><para><code>on</code> - enables default warning level for the tool.</para></listitem>
              <listitem><para><code>all</code> - enables all warnings.</para></listitem>
            </itemizedlist>
            Default value is <code>all</code>.
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry><term><literal>warnings-as-errors</literal></term>
        <listitem>
          <simpara>
            The <code>&lt;warnings-as-errors&gt;</code> makes it possible to
            treat warnings as errors and abort compilation on a warning. The
            value <code>on</code> enables this behaviour. The default value is
            <code>off</code>.
          </simpara>
        </listitem>
      </varlistentry>

      <varlistentry><term><literal>build</literal></term>

        <listitem>
          <para><emphasis role="bold">Allowed values:</emphasis> <literal>no</literal></para>

          <para>
            The <code>build</code> feature is used to conditionally disable
            build of a target. If <code>&lt;build&gt;no</code> is in properties
            when building a target, build of that target is skipped. Combined
            with conditional requirements this allows you to skip building some
            target in configurations where the build is known to fail.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry><term><anchor id="bbv2.builtin.features.tag"/><literal>tag</literal></term>

        <listitem><para>The <literal>tag</literal> feature is used to customize
        the name of the generated files. The value should have the form:
<programlisting>@<replaceable>rulename</replaceable></programlisting> where
        <replaceable>rulename</replaceable> should be a name of a rule with the
        following signature:
<programlisting>rule tag ( name : type ? : property-set )</programlisting>
        The rule will be called for each target with the default name computed
        by Boost.Build, the type of the target, and property set. The rule can
        either return a string that must be used as the name of the target, or
        an empty string, in which case the default name will be used.
        </para>

        <para>Most typical use of the <literal>tag</literal> feature is to
        encode build properties, or library version in library target names. You
        should take care to return non-empty string from the tag rule only for
        types you care about &#x2014; otherwise, you might end up modifying
        names of object files, generated header file and other targets for which
        changing names does not make sense.</para>
        </listitem>
      </varlistentry>

      <varlistentry><term><literal>debug-symbols</literal></term>

        <listitem>
          <para><emphasis role="bold">Allowed values:</emphasis> <literal>on</literal>, <literal>off</literal>.</para>

          <para>The <literal>debug-symbols</literal> feature specifies if
          produced object files, executables and libraries should include
          debug information.
          Typically, the value of this feature is implicitly set by the
          <literal>variant</literal> feature, but it can be explicitly
          specified by the user. The most common usage is to build
          release variant with debugging information.</para>
        </listitem>
      </varlistentry>

      <varlistentry><term><literal>target-os</literal></term>
        <listitem>

          <anchor id="bbv2.reference.features.target-os"/>

          <para>
            The operating system for which the code is to be generated. The
            compiler you used should be the compiler for that operating
            system. This option causes Boost.Build to use naming conventions
            suitable for that operating system, and adjust build process
            accordingly. For example, with gcc, it controls if import
            libraries are produced for shared libraries or not.                       
          </para>

          <para>The complete list of possible values for this feature is: 
            aix, bsd, cygwin, darwin, freebsd, hpux, iphone, linux, netbsd,
            openbsd, osf, qnx, qnxnto, sgi, solaris, unix, unixware, windows.
          </para>

          <para>See <xref linkend="bbv2.tasks.crosscompile"/> for details of
          crosscompilation</para>

        </listitem>
      </varlistentry>


      <varlistentry><term><literal>architecture</literal></term>
        <listitem>

          <para>The <literal>architecture</literal> features specifies
          the general processor familty to generate code for.</para>

        </listitem>
      </varlistentry>

      <varlistentry><term><literal>instruction-set</literal></term>
        <indexterm><primary>instruction-set</primary></indexterm>
        <listitem>
          <para>
            <emphasis role="bold">Allowed values:</emphasis> depend on the used
            toolset.
          </para>

          <para>The <literal>instruction-set</literal> specifies for which
          specific instruction set the code should be generated.  The
          code in general might not run on processors with older/different
          instruction sets.</para>

          <para>While Boost.Build allows a large set of possible values
          for this features, whether a given value works depends on which
          compiler you use. Please see
          <xref linkend="bbv2.reference.tools.compilers"/> for details.
          </para>

        </listitem>
      </varlistentry>

      <varlistentry><term><literal>address-model</literal></term>
        <indexterm><primary>64-bit compilation</primary></indexterm>
        <listitem>
          <para><emphasis role="bold">Allowed values:</emphasis> <literal>32</literal>, <literal>64</literal>.</para>

          <para>The <literal>address-model</literal> specifies if 32-bit or
          64-bit code should be generated by the compiler. Whether this feature
          works depends on the used compiler, its version, how the compiler is
          configured, and the values of the <literal>architecture</literal>
          <literal>instruction-set</literal>
          features. Please see <xref linkend="bbv2.reference.tools.compilers"/>
          for details.</para>
        </listitem>
      </varlistentry>

      <varlistentry><term><literal>c++-template-depth</literal></term>
        <listitem>
          <para>
            <emphasis role="bold">Allowed values:</emphasis> Any positive
            integer.
          </para>

          <para>
            This feature allows configuring a C++ compiler with the maximal
            template instantiation depth parameter. Specific toolsets may or may
            not provide support for this feature depending on whether their
            compilers provide a corresponding command-line option.
          </para>

          <para>
            <emphasis role="bold">Note:</emphasis> Due to some internal details
            in the current Boost Build implementation it is not possible to have
            features whose valid values are all positive integer. As a
            workaround a large set of allowed values has been defined for this
            feature and, if a different one is needed, user can easily add it by
            calling the feature.extend rule.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry><term><literal>embed-manifest</literal></term>
        <listitem>

          <indexterm><primary>manifest file</primary><secondary>embedding</secondary></indexterm>
          <indexterm><primary>embed-manifest</primary></indexterm>

          <para>
            <emphasis role="bold">Allowed values:</emphasis> on, off.
          </para>

          <para>This feature is specific to the msvc toolset (see
          <xref linkend="bbv2.reference.tools.compiler.msvc"/>),
          and controls whether the manifest files should be embedded inside
          executables and shared libraries, or placed alongside them.  This
          feature corresponds to the IDE option found in the project settings dialog,
          under <menuchoice><guimenu>Configuration Properties</guimenu> 
            <guisubmenu>Manifest Tool</guisubmenu>
            <guisubmenu>Input and Output</guisubmenu>
            <guimenuitem>Embed manifest</guimenuitem> </menuchoice>.
          </para>

        </listitem>
      </varlistentry>


    </variablelist>
  </section>

    <section id="bbv2.reference.tools">
      <title>Builtin tools</title>

      <para>Boost.Build comes with support for a large number of C++ compilers,
      and other tools. This section documents how to use those tools.</para>

      <para>Before using any tool, you must declare your intention, and possibly
      specify additional information about the tool's configuration. This is
      done by calling the <code>using</code> rule, typically in your
      <filename>user-config.jam</filename>, for example:</para>
<programlisting>
using gcc ;
</programlisting>
    <para>additional parameters can be passed just like for other rules, for example:</para>
<programlisting>
using gcc : 4.0 : g++-4.0 ;
</programlisting>
      


      <para>The options that can be passed to each tool are documented in the
      subsequent sections.</para>

      <section id="bbv2.reference.tools.compilers">

        <title>C++ Compilers</title>

        <para>This section lists all Boost.Build modules that support C++
          compilers and documents how each one can be initialized.  The name
          of support module for compiler is also the value for
          the <code>toolset</code> feature that can be used to explicitly
          request that compiler. </para>

        <section id="bbv2.reference.tools.compiler.gcc">

          <title>GNU C++</title>

          <para>The <code>gcc</code> module supports the
          <ulink url="http://gcc.gnu.org">GNU C++ compiler</ulink>
          on Linux, a number of Unix-like system including SunOS and on Windows 
          (either <ulink url="http://www.cygwin.com">Cygwin</ulink> or 
          <ulink url="http://www.mingw.org">MinGW</ulink>). On Mac OSX, it is recommended
          to use system gcc, see <xref linkend="bbv2.reference.tools.compiler.darwin"/>.
          </para>

          <para>The <code>gcc</code> module is initialized using the following
          syntax:</para>
          <programlisting>
using gcc : &toolset_ops; ;</programlisting>

          &using_repeation;

          <!-- FIXME: mention everywhere what is the semantic
          of version is -->

          <para>
          If the version is not explicitly specified, it will be
          automatically detected by running the compiler with the <code>-v</code>
          option. If the command is not specified, the <command>g++</command>
          binary will be searched in <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>

            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>

            <xi:include href="fragments.xml" xpointer="xpointer(id('root_option')/*)"
                        parse="xml"/>

            <varlistentry>
              <term><literal>rc</literal></term>

              <listitem>
                <para>Specifies the resource compiler command
                that will be used with the version of gcc that is being
                configured. This setting makes sense only for Windows and only
                if you plan to use resource files. By
                default <command>windres</command> will be used.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>rc-type</literal></term>

              <listitem>
                <para>Specifies the type of resource compiler. The value can
                be either <code>windres</code> for msvc resource compiler,
                or <code>rc</code> for borland's resource compiler.</para>
              </listitem>
            </varlistentry>

          </variablelist>

          <indexterm><primary>64-bit compilation</primary>
          <secondary>gcc</secondary></indexterm>

          In order to compile 64-bit applications, you have to specify
          <code>address-model=64</code>, and the <code>instruction-set</code>
          feature should refer to a 64 bit processor. Currently, those
          include <literal>nocona</literal>, <literal>opteron</literal>,
          <literal>athlon64</literal> and <literal>athlon-fx</literal>.

        </section>

        <section id="bbv2.reference.tools.compiler.darwin">

          <title>Apple Darwin gcc</title>

          <para>The <code>darwin</code> module supports the version of gcc that is
          modified and provided by Apple. The configuration is essentially identical
          to that of the gcc module.
          </para>

          <para>
          <indexterm><primary>fat binaries</primary></indexterm>
          The darwin toolset can generate so called "fat"
          binaries&#x2014;binaries that can run support more than one
          architecture, or address mode. To build a binary that can run both
          on Intel and PowerPC processors, specify
          <code>architecture=combined</code>. To build a binary that can run
          both in 32-bit and 64-bit modes, specify
          <code>address-model=32_64</code>. If you specify both of those
          properties, a "4-way" fat binary will be generated.
          </para>

        </section>

        <section id="bbv2.reference.tools.compiler.msvc">

          <title>Microsoft Visual C++</title>

          <para>The <code>msvc</code> module supports the
          <ulink url="http://msdn.microsoft.com/visualc/">Microsoft Visual
          C++</ulink> command-line tools on Microsoft Windows. The supported
          products and versions of command line tools are listed below:</para>
          <itemizedlist>
            <listitem><para>Visual Studio 2010&#x2014;10.0</para></listitem>
            <listitem><para>Visual Studio 2008&#x2014;9.0</para></listitem>
            <listitem><para>Visual Studio 2005&#x2014;8.0</para></listitem>
            <listitem><para>Visual Studio .NET 2003&#x2014;7.1</para></listitem>
            <listitem><para>Visual Studio .NET&#x2014;7.0</para></listitem>
            <listitem><para>Visual Studio 6.0, Service Pack 5&#x2014;6.5</para></listitem>
          </itemizedlist>

          <para>The <code>msvc</code> module is initialized using the following
          syntax:</para>
          <programlisting>
using msvc : &toolset_ops; ;
          </programlisting>
          &using_repeation;
          <para>If the version is not explicitly specified, the most recent
          version found in the registry will be used instead. If the special
          value <code>all</code> is passed as the version, all versions found in
          the registry will be configured. If a version is specified, but the
          command is not, the compiler binary will be searched in standard
          installation paths for that version, followed by <envar>PATH</envar>.
          </para>

          <para>The compiler command should be specified using forward slashes,
          and quoted.</para>

          &option_list_intro;
          <variablelist>

            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>

            <varlistentry>
              <term><literal>assembler</literal></term>

              <listitem><para>The command that compiles assembler sources. If
              not specified, <command>ml</command> will be used. The command
              will be invoked after the setup script was executed and adjusted
              the <envar>PATH</envar> variable.</para></listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>compiler</literal></term>

              <listitem><para>The command that compiles C and C++ sources. If
              not specified, <command>cl</command> will be used. The command
              will be invoked after the setup script was executed and adjusted
              the <envar>PATH</envar> variable.</para></listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>compiler-filter</literal></term>

              <listitem><para>Command through which to pipe the output of
              running the compiler. For example to pass the output to STLfilt.
              </para></listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>idl-compiler</literal></term>

              <listitem><para>The command that compiles Microsoft COM interface
              definition files. If not specified, <command>midl</command> will
              be used. The command will be invoked after the setup script was
              executed and adjusted the <envar>PATH</envar> variable.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>linker</literal></term>

              <listitem><para>The command that links executables and dynamic
              libraries. If not specified, <command>link</command> will be used.
              The command will be invoked after the setup script was executed
              and adjusted the <envar>PATH</envar> variable.</para></listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>mc-compiler</literal></term>

              <listitem><para>The command that compiles Microsoft message
              catalog files. If not specified, <command>mc</command> will be
              used. The command will be invoked after the setup script was
              executed and adjusted the <envar>PATH</envar> variable.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>resource-compiler</literal></term>

              <listitem><para>The command that compiles resource files. If not
              specified, <command>rc</command> will be used. The command will be
              invoked after the setup script was executed and adjusted the
              <envar>PATH</envar> variable.</para></listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>setup</literal></term>

              <listitem><para>The filename of the global environment setup
              script to run before invoking any of the tools defined in this
              toolset. Will not be used in case a target platform specific
              script has been explicitly specified for the current target
              platform. Used setup script will be passed the target platform
              identifier (x86, x86_amd64, x86_ia64, amd64 or ia64) as a
              arameter. If not specified a default script is chosen based on the
              used compiler binary, e.g. <command>vcvars32.bat</command> or
              <command>vsvars32.bat</command>.</para></listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>setup-amd64</literal></term>
              <term><literal>setup-i386</literal></term>
              <term><literal>setup-ia64</literal></term>

              <listitem><para>The filename of the target platform specific
              environment setup script to run before invoking any of the tools
              defined in this toolset. If not specified the global environment
              setup script is used.</para></listitem>
            </varlistentry>
        </variablelist>

          <section id="v2.reference.tools.compiler.msvc.64">
            <title>64-bit support</title>

            <indexterm><primary>64-bit compilation</primary>
            <secondary>Microsoft Visual Studio</secondary></indexterm>

            <para>Starting with version 8.0, Microsoft Visual Studio can
            generate binaries for 64-bit processor, both 64-bit flavours of x86
            (codenamed AMD64/EM64T), and Itanium (codenamed IA64). In addition,
            compilers that are itself run in 64-bit mode, for better
            performance, are provided. The complete list of compiler
            configurations are as follows (we abbreviate AMD64/EM64T to just
            AMD64):</para>

            <itemizedlist>
              <listitem><para>32-bit x86 host, 32-bit x86 target</para>
              </listitem>
              <listitem><para>32-bit x86 host, 64-bit AMD64 target</para>
              </listitem>
              <listitem><para>32-bit x86 host, 64-bit IA64 target</para>
              </listitem>
              <listitem><para>64-bit AMD64 host, 64-bit AMD64 target</para>
              </listitem>
              <listitem><para>64-bit IA64 host, 64-bit IA64 target</para>
              </listitem>
            </itemizedlist>
            <para>
            The 32-bit host compilers can be always used, even on 64-bit
            Windows. On the contrary, 64-bit host compilers require both 64-bit
            host processor and 64-bit Windows, but can be faster. By default,
            only 32-bit host, 32-bit target compiler is installed, and
            additional compilers need to be installed explicitly.
            </para>

            <para>To use 64-bit compilation you should:</para>
            <orderedlist>
              <listitem><para>Configure you compiler as usual. If you provide a
              path to the compiler explicitly, provide the path to the 32-bit
              compiler. If you try to specify the path to any of 64-bit
              compilers, configuration will not work.</para></listitem>

              <listitem><para>When compiling, use <code>address-model=64</code>,
              to generate AMD64 code.</para></listitem>

              <listitem><para>To generate IA64 code, use
              <code>architecture=ia64</code></para></listitem>
            </orderedlist>

            <para>The (AMD64 host, AMD64 target) compiler will be used
            automatically when you are generating AMD64 code and are running
            64-bit Windows on AMD64. The (IA64 host, IA64 target) compiler will
            never be used, since nobody has an IA64 machine to test.</para>

            <para>It is believed that AMD64 and EM64T targets are essentially
            compatible. The compiler options <code>/favor:AMD64</code> and
            <code>/favor:EM64T</code>, which are accepted only by AMD64
            targeting compilers, cause the generated code to be tuned to a
            specific flavor of 64-bit x86. Boost.Build will make use of those
            options depending on the value of the<code>instruction-set</code>
            feature.</para>
          </section>
        </section>

        <section id="bbv2.reference.tools.compiler.intel">

          <title>Intel C++</title>

          <para>The <code>intel-linux</code> and <code>intel-win</code> modules
          support the Intel C++ command-line compiler&#x2014;the <ulink url=
          "http://www.intel.com/software/products/compilers/clin/index.htm">Linux</ulink>
          and <ulink url=
          "http://www.intel.com/cd/software/products/asmo-na/eng/compilers/284527.htm">
          Windows</ulink> versions respectively.</para>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using intel-linux : &toolset_ops; ;</programlisting>
          <para>or</para>
          <programlisting>
using intel-win : &toolset_ops; ;</programlisting>
          <para>respectively.</para>

          &using_repeation;

          <para>
          If compiler command is not specified, then Boost.Build will
          look in <envar>PATH</envar> for an executable <command>icpc</command>
          (on Linux), or <command>icc.exe</command> (on Windows).
          </para>

          &option_list_intro;
          <variablelist>

            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>

          </variablelist>

          <para>The Linux version supports the following additional options:</para>
          <variablelist>

            <xi:include href="fragments.xml" xpointer="xpointer(id('root_option')/*)"
                        parse="xml"/>

          </variablelist>

          <!-- the compatibility option appears to be messed up -->

        </section>

        <section id="bbv2.reference.tools.compiler.acc">

          <title>HP aC++ compiler</title>

          <para>The <code>acc</code> module supports the
<ulink url="http://h21007.www2.hp.com/dspp/tech/tech_TechSoftwareDetailPage_IDX/1,1703,1740,00.html">HP aC++ compiler</ulink>
          for the HP-UX operating system.</para>

          <para>The module is initialized using the following
          syntax:</para>
          <programlisting>
using acc : &toolset_ops; ;</programlisting>

          &using_repeation;


          <para>
            If the command is not specified, the <command>aCC</command>
          binary will be searched in <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>
            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>
          </variablelist>

        </section>

        <section id="bbv2.reference.tools.compiler.borland">

          <title>Borland C++ Compiler</title>

          <para>The <code>borland</code> module supports the command line
          C++ compiler included in
          <ulink url="http://www.borland.com/us/products/cbuilder/index.html">C++ Builder 2006</ulink>
          product and earlier version of it, running on Microsoft Windows.</para>

          <para>The supported products are listed below. The version reported
          by the command lines tools is also listed for reference.:</para>
          <itemizedlist>
            <listitem><para>C++ Builder 2006&#x2014;5.8.2</para></listitem>
            <listitem><para>CBuilderX&#x2014;5.6.5, 5.6.4 (depending on release)</para></listitem>
            <listitem><para>CBuilder6&#x2014;5.6.4</para></listitem>
            <listitem><para>Free command line tools&#x2014;5.5.1</para></listitem>
          </itemizedlist>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using borland : &toolset_ops; ;</programlisting>

          &using_repeation;

          <para>If the command is not specified, Boost.Build will search for
          a binary named <command>bcc32</command> in <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>
            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>
          </variablelist>

        </section>

        <section id="bbv2.reference.tools.compiler.como">

          <title>Comeau C/C++ Compiler</title>

          <para>The <code>como-linux</code> and the <code>como-win</code>
          modules supports the
          <ulink url="http://www.comeaucomputing.com/">Comeau C/C++ Compiler</ulink>
          on Linux and Windows respectively.</para>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using como-linux : &toolset_ops; ;</programlisting>

          &using_repeation;

          <para>If the command is not specified, Boost.Build will search for
          a binary named <command>como</command> in
          <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>
            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>
          </variablelist>

          <para>Before using the Windows version of the compiler, you need to
          setup necessary environment variables per compiler's documentation. In
          particular, the <envar>COMO_XXX_INCLUDE</envar> variable should be
          set, where <envar>XXX</envar> corresponds to the used backend C
          compiler.</para>
        </section>

        <section id="bbv2.reference.tools.compiler.cw">

          <title>Code Warrior</title>

          <para>The <code>cw</code> module support CodeWarrior compiler,
          originally produced by Metrowerks and presently developed by
          Freescale. Boost.Build supports only the versions of the compiler that
          target x86 processors. All such versions were released by Metrowerks
          before aquisition and are not sold any longer. The last version known
          to work is 9.4.</para>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using cw : &toolset_ops; ;</programlisting>

          &using_repeation;

          <para>If the command is not specified, Boost.Build will search for a
          binary named <command>mwcc</command> in default installation paths and
          in <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>

            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>

            <xi:include href="fragments.xml" xpointer="xpointer(id('root_option')/*)"
                        parse="xml"/>

            <varlistentry>
              <term><literal>setup</literal></term>

              <listitem><para>The command that sets up environment variables
              prior to invoking the compiler. If not specified,
              <command>cwenv.bat</command> alongside the compiler binary
              will be used.</para>
              </listitem>
            </varlistentry>


            <varlistentry>
              <term><literal>compiler</literal></term>

              <listitem><para>The command that compiles C and C++ sources.
              If not specified, <command>mwcc</command> will be used. The
              command will be invoked after the setup script was
              executed and adjusted the <envar>PATH</envar> variable.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>linker</literal></term>

              <listitem><para>The command that links executables and dynamic
              libraries.
              If not specified, <command>mwld</command> will be used. The
              command will be invoked after the setup script was
              executed and adjusted the <envar>PATH</envar> variable.</para>
              </listitem>
            </varlistentry>

          </variablelist>

        </section>

        <section id="bbv2.reference.tools.compiler.dmc">

          <title>Digital Mars C/C++ Compiler</title>

          <para>The <code>dmc</code> module supports the
          <ulink url="http://www.digitalmars.com/">Digital Mars C++ compiler.</ulink>
          </para>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using dmc : &toolset_ops; ;</programlisting>

          &using_repeation;

          <para>If the command is not specified, Boost.Build will search for
          a binary named <command>dmc</command> in
          <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>
            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>
          </variablelist>

        </section>

        <section id="bbv2.reference.tools.compiler.hp_cxx">

          <title>HP C++ Compiler for Tru64 Unix</title>

          <para>The <code>hp_cxx</code> modules supports the
          <ulink url="http://h30097.www3.hp.com/cplus/?jumpid=reg_R1002_USEN">
            HP C++ Compiler</ulink> for Tru64 Unix.</para>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using hp_cxx : &toolset_ops; ;</programlisting>

          &using_repeation;

          <para>If the command is not specified, Boost.Build will search for
          a binary named <command>hp_cxx</command> in <envar>PATH</envar>.</para>

          &option_list_intro;
          <variablelist>
            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>
          </variablelist>

        </section>

        <section id="bbv2.reference.tools.compiler.sun">

          <title>Sun Studio</title>

          <para>The <code>sun</code> module supports the
          <ulink url="http://developers.sun.com/sunstudio/index.jsp">
          Sun Studio</ulink> C++ compilers for the Solaris OS.</para>

          <para>The module is initialized using the following syntax:</para>
          <programlisting>
using sun : &toolset_ops; ;</programlisting>

          &using_repeation;

          <para>If the command is not specified, Boost.Build will search for
          a binary named <command>CC</command>
          in <filename>/opt/SUNWspro/bin</filename> and in
          <envar>PATH</envar>.</para>

          <para>When using this compiler on complex C++ code, such as the
          <ulink url="http://boost.org">Boost C++ library</ulink>, it is
          recommended to specify the following options when intializing the
          <code>sun</code> module:
          <screen>
-library=stlport4 -features=tmplife -features=tmplrefstatic
          </screen> See the <ulink url="http://blogs.sun.com/sga/entry/command_line_options">
          Sun C++ Frontend Tales</ulink> for details.</para>

          &option_list_intro;
          <variablelist>
            <xi:include href="fragments.xml" xpointer="xpointer(id('common_options')/*)"
                        parse="xml"/>
          </variablelist>

          <indexterm><primary>64-bit compilation</primary>
          <secondary>Sun Studio</secondary></indexterm>
          Starting with Sun Studio 12, you can create 64-bit applications
          by using the <code>address-model=64</code> property.

        </section>

        <section id="bbv2.reference.tools.compiler.vacpp">

          <title>IBM Visual Age</title>
          <para>The <code>vacpp</code> module supports the
          <ulink url="http://www.ibm.com/software/ad/vacpp">IBM Visual
          Age</ulink> C++ Compiler, for the AIX operating system. Versions
          7.1 and 8.0 are known to work.</para>

          <para>The module is initialized using the following
          syntax:</para>
          <programlisting>
using vacpp ;</programlisting>

          <para>The module does not accept any initialization options. The
          compiler should be installed in the <filename>/usr/vacpp/bin</filename>
          directory.</para>

          <para>Later versions of Visual Age are known as XL C/C++. They
          were not tested with the the <code>vacpp</code> module.</para>

        </section>

      </section>

      <section>
        <title>Third-party libraries</title>

        <para>Boost.Build provides special support for some
        third-party C++ libraries, documented below.</para>

        <section id="bbv2.reference.tools.libraries.stlport">
          <title>STLport library</title>
          <indexterm><primary>STLport</primary></indexterm>

          <para>The <ulink url="http://stlport.org">STLport</ulink> library
          is an alternative implementation of C++ runtime library. Boost.Build
          supports using that library on Windows platfrom.  Linux is
          hampered by different naming of libraries in each STLport
          version and is not officially supported.</para>

          <para>Before using STLport, you need to configure it in
          <filename>user-config.jam</filename> using the following syntax:
          </para>
          <programlisting>
using stlport : <optional><replaceable>version</replaceable></optional> : <replaceable>header-path</replaceable> : <optional><replaceable>library-path</replaceable></optional> ;
</programlisting>
          <para>
          Where <replaceable>version</replaceable> is the version of
          STLport, for example <literal>5.1.4</literal>,
          <replaceable>headers</replaceable> is the location where
          STLport headers can be found, and <replaceable>libraries</replaceable>
          is the location where STLport libraries can be found.
          The version should always be provided, and the library path should
          be provided if you're using STLport's implementation of
          iostreams. Note that STLport 5.* always uses its own iostream
          implementation, so the library path is required.
          </para>

          <para>When STLport is configured, you can build with STLport by
          requesting <literal>stdlib=stlport</literal> on the command line.
          </para>

        </section>

        <section id="bbv2.reference.tools.libraries.zlib">
          <title>zlib</title>
          <indexterm><primary>zlib</primary></indexterm>

          <para>Provides support for the
          <ulink url="http://www.zlib.net">zlib</ulink> library.  zlib
          can be configured either to use precompiled binaries or to
          build the library from source.</para>

          <para>zlib can be initialized using the following syntax</para>
          <programlisting>
using zlib : <optional><replaceable>version</replaceable></optional> : <optional><replaceable>options</replaceable></optional> : <optional><replaceable>condition</replaceable></optional> : <optional><replaceable>is-default</replaceable></optional> ;
          </programlisting>
          <para>Options for using a prebuilt library:</para>
          <variablelist>
            <varlistentry>
              <term><literal>search</literal></term>
              <listitem>
                <para>The directory containing the zlib binaries.</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><literal>name</literal></term>
              <listitem>
                <para>Overrides the default library name.</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><literal>include</literal></term>
              <listitem>
                <para>The directory containing the zlib headers.</para>
              </listitem>
            </varlistentry>
          </variablelist>
          <para>If none of these options is specified, then the environmental
          variables ZLIB_LIBRARY_PATH, ZLIB_NAME, and ZLIB_INCLUDE will be
          used instead.</para>
          <para>Options for building zlib from source:</para>
          <variablelist>
            <varlistentry>
              <term><literal>source</literal></term>
              <listitem>
                <para>The zlib source directory.  Defaults to the
                environmental variable ZLIB_SOURCE.</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><literal>tag</literal></term>
              <listitem>
                <para>Sets the <link linkend="bbv2.builtin.features.tag">tag</link>
                property to adjust the file name of the library.  Ignored
                when using precompiled binaries.</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><literal>build-name</literal></term>
              <listitem>
                <para>The base name to use for the compiled library.
                Ignored when using precompiled binaries.</para>
              </listitem>
            </varlistentry>
          </variablelist>
          <para>Examples:</para>
          <programlisting>
# Find zlib in the default system location
using zlib ;
# Build zlib from source
using zlib : 1.2.7 : &lt;source&gt;/home/steven/zlib-1.2.7 ;
# Find zlib in /usr/local
using zlib : 1.2.7 : &lt;include&gt;/usr/local/include &lt;search&gt;/usr/local/lib ;
# Build zlib from source for msvc and find
# prebuilt binaries for gcc.
using zlib : 1.2.7 : &lt;source&gt;C:/Devel/src/zlib-1.2.7 : &lt;toolset&gt;msvc ;
using zlib : 1.2.7 : : &lt;toolset&gt;gcc ;
</programlisting>
        </section>

      </section>

      <section>
        <title>Documentation tools</title>

        <para>Boost.Build support for the Boost documentation tools is
        documented below.
        </para>

        <section id="bbv2.reference.tools.doc.xsltproc">
          <title>xsltproc</title>
          <indexterm><primary>xsltproc</primary></indexterm>

          <para>To use xsltproc, you first need to configure it using the following syntax:</para>
          <programlisting>
using xsltproc : <optional><replaceable>xsltproc</replaceable></optional> ;
</programlisting>
          <para>
          Where <replaceable>xsltproc</replaceable> is the xsltproc executable.
          If <replaceable>xsltproc</replaceable> is not specified, and the
          variable XSLTPROC is set, the value of XSLTPROC will be used.
          Otherwise, xsltproc will be searched for in PATH.
          </para>

          
          &option_list_intro;
          <variablelist>

            <varlistentry>
              <indexterm><primary>xsl:param</primary></indexterm>
              <term><literal>xsl:param</literal></term>
              <listitem>
                <para>Values should have the form
                <replaceable>name</replaceable>=<replaceable>value</replaceable></para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <indexterm><primary>xsl:path</primary></indexterm>
              <term><literal>xsl:path</literal></term>
              <listitem>
                <para>Sets an additional search path for xi:include elements.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <indexterm><primary>catalog</primary></indexterm>
              <term><literal>catalog</literal></term>
              <listitem>
                <para>A catalog file used to rewrite remote URL's to a local copy.</para>
              </listitem>
            </varlistentry>

          </variablelist>

          <para>The xsltproc module provides the following rules.  Note that
          these operate on jam targets and are intended to be used by another
          toolset, such as boostbook, rather than directly by users.
          </para>
          <variablelist>

            <varlistentry>
              <indexterm><primary>xslt</primary></indexterm>
              <term><literal>xslt</literal></term>
              <listitem>
                <programlisting>
rule xslt ( target : source stylesheet : properties * )
</programlisting>
                <para>Runs xsltproc to create a single output file.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <indexterm><primary>xslt-dir</primary></indexterm>
              <term><literal>xslt-dir</literal></term>
              <listitem>
                <programlisting>
rule xslt-dir ( target : source stylesheet : properties * : dirname )
</programlisting>
                <para>Runs xsltproc to create multiple outputs in a directory.
                <literal>dirname</literal> is unused, but exists for
                historical reasons.  The output directory is determined from the
                target.
                </para>
              </listitem>
            </varlistentry>

          </variablelist>

        </section>

        <section id="bbv2.reference.tools.doc.boostbook">
          <title>boostbook</title>
          <indexterm><primary>boostbook</primary><secondary>module</secondary></indexterm>

          <para>To use boostbook, you first need to configure it using the following syntax:</para>
          <programlisting>
using boostbook : <optional><replaceable>docbook-xsl-dir</replaceable></optional> : <optional><replaceable>docbook-dtd-dir</replaceable></optional> : <optional><replaceable>boostbook-dir</replaceable></optional> ;
</programlisting>
          <para>
          <replaceable>docbook-xsl-dir</replaceable> is the DocBook XSL stylesheet
          directory. If not provided, we use DOCBOOK_XSL_DIR from the environment
          (if available) or look in standard locations.  Otherwise, we let the
          XML processor load the stylesheets remotely.
          </para>

          <para>
          <replaceable>docbook-dtd-dir</replaceable> is the DocBook DTD directory.
          If not provided, we use DOCBOOK_DTD_DIR From the environment (if
          available) or look in standard locations.  Otherwise, we let the XML
          processor load the DTD remotely.
          </para>

          <para>
          <replaceable>boostbook-dir</replaceable> is the BoostBook directory
          with the DTD and XSL subdirs.
          </para>

          <para>The boostbook module depends on xsltproc.  For pdf or ps output,
          it also depends on fop.
          </para>
          
          &option_list_intro;
          <variablelist>

            <varlistentry>
              <indexterm><primary>format</primary></indexterm>
              <indexterm><primary>html</primary></indexterm>
              <indexterm><primary>xhtml</primary></indexterm>
              <indexterm><primary>htmlhelp</primary></indexterm>
              <indexterm><primary>onehtml</primary></indexterm>
              <indexterm><primary>man</primary></indexterm>
              <indexterm><primary>pdf</primary></indexterm>
              <indexterm><primary>ps</primary></indexterm>
              <indexterm><primary>docbook</primary></indexterm>
              <indexterm><primary>fo</primary></indexterm>
              <indexterm><primary>tests</primary></indexterm>
              <term><literal>format</literal></term>
              <listitem>
                <para>
                  <emphasis role="bold">Allowed values:</emphasis>
                  <literal>html</literal>, <literal>xhtml</literal>,
                  <literal>htmlhelp</literal>, <literal>onehtml</literal>,
                  <literal>man</literal>, <literal>pdf</literal>,
                  <literal>ps</literal>, <literal>docbook</literal>,
                  <literal>fo</literal>, <literal>tests</literal>.
                </para>


                <para>The <literal>format</literal> feature determines the type
                of output produced by the boostbook rule.</para>
              </listitem>
            </varlistentry>

          </variablelist>

          <para>The boostbook module defines a rule for creating a target
          following the common syntax.</para>

          <variablelist>

            <varlistentry>
              <indexterm><primary>boostbook</primary><secondary>rule</secondary></indexterm>
              <term><literal>boostbook</literal></term>
              <listitem>
                <programlisting>
rule boostbook ( target-name : sources * : requirements * : default-build * )
</programlisting>
                <para>Creates a boostbook target.</para>
              </listitem>
            </varlistentry>

          </variablelist>

        </section>

        <section id="bbv2.reference.tools.doc.doxygen">
          <title>doxygen</title>
          <indexterm><primary>doxygen</primary></indexterm>

          <para>To use doxygen, you first need to configure it using the following syntax:</para>
          <programlisting>
using doxygen : <optional><replaceable>name</replaceable></optional> ;
</programlisting>
          <para>
          <replaceable>name</replaceable> is the doxygen command.
          If it is not specified, it will be found in the PATH.
          </para>

          <para>The doxygen module depends on the boostbook module when
          generating BoostBook XML.
          </para>

          &option_list_intro;
          <variablelist>

            <varlistentry>
              <indexterm><primary>doxygen:param</primary></indexterm>
              <term><literal>doxygen:param</literal></term>
              <listitem>
                <para>All the values of <literal>doxygen:param</literal>
                 are added to the doxyfile.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <indexterm><primary>prefix</primary></indexterm>
              <term><literal>prefix</literal></term>
              <listitem>
                <para>Specifies the common prefix of all headers
                when generating BoostBook XML.  Everything before
                this will be stripped off.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <indexterm><primary>reftitle</primary></indexterm>
              <term><literal>reftitle</literal></term>
              <listitem>
                <para>Specifies the title of the library-reference section,
                when generating BoostBook XML.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <indexterm><primary>doxygen:xml-imagedir</primary></indexterm>
              <term><literal>doxygen:xml-imagedir</literal></term>
              <listitem>
                <para>When generating BoostBook XML, specifies the
                directory in which to place the images generated
                from LaTex formulae.</para>
                <warning><para>The path is interpreted relative to the
                current working directory, not relative to the Jamfile.
                This is necessary to match the behavior of BoostBook.
                </para></warning>
              </listitem>
            </varlistentry>

          </variablelist>

          <para>The doxygen module defines a rule for creating a target
          following the common syntax.</para>

          <variablelist>

            <varlistentry>
              <indexterm><primary>doxygen</primary><secondary>rule</secondary></indexterm>
              <term><literal>doxygen</literal></term>
              <listitem>
                <programlisting>
rule doxygen ( target : sources * : requirements * : default-build * : usage-requirements * )
</programlisting>
                <para>Creates a doxygen target.  If the target name
                ends with .html, then this will generate an html
                directory.  Otherwise it will generate BoostBook XML.
                </para>
              </listitem>
            </varlistentry>

          </variablelist>

        </section>

        <section id="bbv2.reference.tools.doc.quickbook">
          <title>quickbook</title>
          <indexterm><primary>quickbook</primary></indexterm>

          <para>The quickbook module provides a generator to convert from
          Quickbook to BoostBook XML.</para>

          <para>To use quickbook, you first need to configure it using the following syntax:</para>
          <programlisting>
using quickbook : <optional><replaceable>command</replaceable></optional> ;
</programlisting>
          <para>
          <replaceable>command</replaceable> is the quickbook executable.
          If it is not specified, Boost.Build will compile it from source.
          If it is unable to find the source it will search for a quickbook
          executable in PATH.
          </para>

        </section>

        <section id="bbv2.reference.tools.doc.fop">
          <title>fop</title>
          <indexterm><primary>fop</primary></indexterm>

          <para>The fop module provides generators to convert from
          XSL formatting objects to Postscript and PDF.</para>

          <para>To use fop, you first need to configure it using the following syntax:</para>
          <programlisting>
using fop : <optional><replaceable>fop-command</replaceable></optional> : <optional><replaceable>java-home</replaceable></optional> : <optional><replaceable>java</replaceable></optional> ;
</programlisting>
          <para>
          <replaceable>fop-command</replaceable> is the command to run fop.
          If it is not specified, Boost.Build will search for it in PATH and
          FOP_HOME.
          </para>
          <para>
          Either <replaceable>java-home</replaceable> or
          <replaceable>java</replaceable>
          can be used to specify where to find java.
          </para>

        </section>

      </section>

    </section>

  <section id="bbv2.reference.modules">
    <title>Builtin modules</title>

    <para>
      This section describes the modules that are provided
      by Boost.Build.  The import rule allows rules from
      one module to be used in another module or Jamfile.
    </para>
    
    <section id="bbv2.reference.modules.modules">
      <title>modules</title>
      <indexterm><primary>modules</primary></indexterm>

      <para>
        The <code>modules</code> module defines basic functionality
        for handling modules.
      </para>

      <para>
        A module defines a number of rules that can be used in other
        modules.  Modules can contain code at the top level to initialize
        the module.  This code is executed the first time the
        module is loaded.
        <note>
          <para>
            A Jamfile is a special kind of module which is managed by
            the build system.  Although they cannot be loaded directly
            by users, the other features of modules are still useful
            for Jamfiles.
          </para>
        </note>
      </para>

      <para>
        Each module has its own namespaces for variables and rules.  If two
        modules A and B both use a variable named X, each one gets its own
        copy of X.  They won't interfere with each other in any way.
        Similarly, importing rules into one module has no effect on any other
        module.
      </para>

      <para>
        Every module has two special variables.
        <code>$(__file__)</code> contains the name of the file that
        the module was loaded from and <code>$(__name__)</code>
        contains the name of the module.
        <note><para><code>$(__file__)</code> does not contain
        the full path to the file.  If you need this, use
        <code>modules.binding</code>.</para></note>
      </para>
      
      <orderedlist>

        <listitem id="bbv2.reference.modules.modules.binding">
          <indexterm zone="bbv2.reference.modules.modules.binding"><primary>binding</primary></indexterm>
          <code language="jam">rule binding ( module-name )</code>
          <para>Returns the filesystem binding of the given module.</para>
          <para>For example, a module can get its own location with:
          <programlisting language="jam">me = [ modules.binding $(__name__) ] ;</programlisting>
          </para>
        </listitem>

        <listitem id="bbv2.reference.modules.modules.poke">
          <indexterm zone="bbv2.reference.modules.modules.poke"><primary>poke</primary></indexterm>
          <code language="jam">rule poke ( module-name ? : variables + : value * )</code>
          <para>Sets the module-local value of a variable.</para>
          <para>For example, to set a variable in the global module:
          <programlisting language="jam">modules.poke : ZLIB_INCLUDE : /usr/local/include ;</programlisting>
          </para>
        </listitem>

        <listitem id="bbv2.reference.modules.modules.peek">
          <indexterm zone="bbv2.reference.modules.modules.peek"><primary>peek</primary></indexterm>
          <code language="jam">rule peek ( module-name ? : variables + )</code>
          <para>Returns the module-local value of a variable.</para>
          <para>
            For example, to read a variable from the global module:
            <programlisting language="jam">local ZLIB_INCLUDE = [ modules.peek : ZLIB_INCLUDE ] ;</programlisting>
          </para>
        </listitem>

        <listitem id="bbv2.reference.modules.modules.call-in">
          <indexterm zone="bbv2.reference.modules.modules.call-in"><primary>call-in</primary></indexterm>
          <code language="jam">rule call-in ( module-name ? : rule-name args * : * ) </code>
          <para>Call the given rule locally in the given module. Use
          this for rules accepting rule names as arguments, so that
          the passed rule may be invoked in the context of the rule's
          caller (for example, if the rule accesses module globals or
          is a local rule).
          <note><para>rules called this way may accept at most
          8 parameters.</para></note></para>
          <para>Example:
<programlisting language="jam">
rule filter ( f : values * )
{
    local m = [ CALLER_MODULE ] ;
    local result ;
    for v in $(values)
    {
        if [ modules.call-in $(m) : $(f) $(v) ]
        {
            result += $(v) ;
        }
    }
    return result ;
}
</programlisting>
          </para>
        </listitem>

        <listitem id="bbv2.reference.modules.modules.load">
          <indexterm zone="bbv2.reference.modules.modules.load"><primary>load</primary></indexterm>
          <code language="jam">rule load ( module-name : filename ? : search * )</code>
          <para>Load the indicated module if it is not already loaded.</para>
          <variablelist>
            <varlistentry>
              <term><literal>module-name</literal></term>
              <listitem><para>Name of module to load.</para></listitem>
            </varlistentry>
          </variablelist>
          <variablelist>
            <varlistentry>
              <term><literal>filename</literal></term>
              <listitem><para>(partial) path to file; Defaults to <code>$(module-name).jam</code></para></listitem>
            </varlistentry>
          </variablelist>
          <variablelist>
            <varlistentry>
              <term><literal>search</literal></term>
              <listitem><para>Directories in which to search for filename.
                  Defaults to <code>$(BOOST_BUILD_PATH)</code>.</para></listitem>
            </varlistentry>
          </variablelist>
        </listitem>

        <listitem id="bbv2.reference.modules.modules.import">
          <indexterm zone="bbv2.reference.modules.modules.import"><primary>import</primary></indexterm>
          <code language="jam">rule import ( module-names + : rules-opt * : rename-opt * )</code>
          <para>Load the indicated module and import rule names into the
          current module. Any members of <code>rules-opt</code> will be
          available without qualification in the caller's module. Any
          members of <code>rename-opt</code> will be taken as the names
          of the rules in the caller's module, in place of the names they
          have in the imported module.  If <code>rules-opt = '*'</code>,
          all rules from the indicated module are imported into the
          caller's module. If <code>rename-opt</code> is supplied, it must have the
          same number of elements as <code>rules-opt</code>.</para>
          <note><para>The <literal>import</literal> rule is available
          without qualification in all modules.</para></note>
          <para>Examples:
<programlisting language="jam">
import path ;
import path : * ;
import path : join ;
import path : native make : native-path make-path ;
</programlisting>
          </para>
        </listitem>

        <listitem id="bbv2.reference.modules.modules.clone-rules">
          <indexterm zone="bbv2.reference.modules.modules.clone-rules"><primary>clone-rules</primary></indexterm>
          <code language="jam">rule clone-rules ( source-module target-module )</code>
          <para>Define exported copies in <code>$(target-module)</code>
          of all rules exported from <code>$(source-module)</code>. Also
          make them available in the global module with qualification,
          so that it is just as though the rules were defined originally
          in <code>$(target-module)</code>.</para>
        </listitem>

      </orderedlist>

    </section>

    <xi:include href="path.xml"/>
    <xi:include href="type.xml"/>
  
  </section>

  <section id="bbv2.reference.class">
    <title>Builtin classes</title>
    <xi:include href="abstract-target.xml"/>
    <xi:include href="project-target.xml"/>
    <xi:include href="main-target.xml"/>
    <xi:include href="basic-target.xml"/>
    <xi:include href="typed-target.xml"/>
    <xi:include href="property-set.xml"/>
  </section>

  <section id="bbv2.reference.buildprocess">
    <title>Build process</title>

    <para>The general overview of the build process was given in the
      <link linkend="bbv2.overview.build_process">user documentation</link>.
      This section provides additional details, and some specific rules.
    </para>

    <para>To recap, building a target with specific properties includes the
      following steps:
      <orderedlist>

        <listitem><para>applying default build,</para></listitem>

        <listitem><para>selecting the main target alternative to use,
          </para></listitem>

        <listitem><para>determining "common" properties,</para></listitem>

        <listitem><para>building targets referred by the sources list and
            dependency properties,</para></listitem>

        <listitem><para>adding the usage requirements produces when building
            dependencies to the "common" properties,</para></listitem>

        <listitem><para>building the target using generators,</para></listitem>

        <listitem><para>computing the usage requirements to be returned.</para></listitem>

      </orderedlist>
    </para>

    <section id="bbv2.reference.buildprocess.alternatives">
      <title>Alternative selection</title>

      <para>When there are several alternatives, one of them must be
        selected. The process is as follows:</para>

      <orderedlist>
        <listitem>
          <simpara>
            For each alternative <emphasis>condition</emphasis> is defined as
            the set of base properties in requirements. [Note: it might be
            better to specify the condition explicitly, as in conditional
            requirements].
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            An alternative is viable only if all properties in condition
            are present in build request.
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            If there's one viable alternative, it's choosen. Otherwise,
            an attempt is made to find one best alternative. An alternative
            a is better than another alternative b, iff the set of properties
            in b's condition is a strict subset of the set of properities of
            'a's condition. If there's one viable alternative, which is
            better than all others, it's selected. Otherwise, an error is
            reported.
          </simpara>
        </listitem>
      </orderedlist>

    </section>

    <section id="bbv2.reference.buildprocess.common">
      <title>Determining common properties</title>

      <para>The "common" properties is a somewhat artificial term. Those are
        the intermediate property set from which both the build request for
        dependencies and properties for building the target are derived.
      </para>

      <para>Since default build and alternatives are already handled, we have
        only two inputs: build requests and requirements. Here are the rules
        about common properties.
      </para>

      <orderedlist>
        <listitem><para>Non-free feature can have only one
            value</para></listitem>

        <listitem><para>A non-conditional property in requirement in always
            present in common properties.</para></listitem>

        <listitem><para>A property in build request is present in
            common properties, unless (2) tells otherwise.</para></listitem>

        <listitem><para>If either build request, or requirements (non-conditional
            or conditional) include an expandable property (either composite,
            or property with specified subfeature value), the behaviour is
            equivalent to explicitly adding all expanded properties to build
            request or requirements.</para></listitem>

        <listitem><para>If requirements include a conditional property, and
            condiiton of this property is true in context of common
            properties, then the conditional property should be in common
            properties as well.</para></listitem>

        <listitem><para>If no value for a feature is given by other rules
            here, it has default value in common properties.</para></listitem>
      </orderedlist>

      <para>Those rules are declarative, they don't specify how to compute the
        common properties. However, they provide enough information for the
        user. The important point is the handling of conditional
        requirements. The condition can be satisfied either by property in
        build request, by non-conditional requirements, or even by another
        conditional property. For example, the following example works as
        expected:
<programlisting>
exe a : a.cpp
      : &lt;toolset&gt;gcc:&lt;variant&gt;release
        &lt;variant&gt;release:&lt;define&gt;FOO ;
</programlisting>
      </para>

    </section>
    
    <section id="bbv2.reference.buildprocess.targetpath">
      <title>Target Paths</title>
      <indexterm><primary>path</primary><secondary>for targets</secondary></indexterm>

      <para>Several factors determine the location of a concrete
      file target.  All files in a project are built under
      the directory bin unless this is overriden by the build-dir project
      attribute.  Under bin is a path that depends on the properties
      used to build each target.  This path is uniquely determined by
      all non-free, non-incidental properties.  For example,
      given a property set containing:
      <code>&lt;toolset&gt;gcc &lt;toolset-gcc:version&gt;4.6.1 &lt;variant&gt;debug
      &lt;warnings&gt;all &lt;define&gt;_DEBUG &lt;include&gt;/usr/local/include
      &lt;link&gt;static</code>,
      the path will be gcc-4.6.1/debug/link-static.  &lt;warnings&gt; is an
      incidental feature and &lt;define&gt; and &lt;include&gt; are
      free features, so they do not affect the path.</para>
      
      <para>Sometimes the paths produced by Boost.Build can become excessively
      long.  There are a couple of command line options that can help with this.
      --abbreviate-paths reduces each element to no more than five characters.
      For example, link-static becomes lnk-sttc.  The --hash option reduces the
      path to a single directory using an MD5 hash.</para>
      
      <para>There are two features that affect the build
      directory.  The &lt;location&gt; feature completely
      overrides the default build directory.  For example,
      <programlisting>exe a : a.cpp : &lt;location&gt;. ;</programlisting>
      builds all the files produced by <code>a</code>
      in the directory of the Jamfile.  This is generally
      discouraged, as it precludes variant builds.</para>
    
      <para>The &lt;location-prefix&gt; feature adds a
      prefix to the path, under the project's build
      directory.  For example,
      <programlisting>exe a : a.cpp : &lt;location-prefix&gt;subdir ;</programlisting>
      will create the files for <code>a</code> in bin/subdir/gcc-4.6.1/debug</para>
    
    </section>

  </section>



  <section id="bbv2.reference.definitions">

    <title>Definitions</title>

    <section id="bbv2.reference.features">
      <title>Features and properties</title>

      <para>A <emphasis>feature</emphasis> is a normalized (toolset-independent)
        aspect of a build configuration, such as whether inlining is
        enabled. Feature names may not contain the '<literal>&gt;</literal>'
        character.</para>

  <!--
    And what about dash?
  -->

      <para>Each feature in a build configuration has one or more
        associated <emphasis>value</emphasis>s. Feature values for non-free features
        may not contain the '<literal>&lt;</literal>', '<literal>:</literal>', or
        '<literal>=</literal>' characters. Feature values for free features may not
        contain the '<literal>&lt;</literal>' character.</para>

      <para>A <emphasis>property</emphasis> is a (feature,value) pair, expressed as
        &lt;feature&gt;value.</para>

      <para>A <emphasis>subfeature</emphasis> is a feature that only exists in the
        presence of its parent feature, and whose identity can be derived
        (in the context of its parent) from its value. A subfeature's
        parent can never be another subfeature. Thus, features and their
        subfeatures form a two-level hierarchy.</para>

      <para>A <emphasis>value-string</emphasis> for a feature <emphasis role="bold">F</emphasis> is a string of
        the form
        <literal>value-subvalue1-subvalue2</literal>...<literal>-subvalueN</literal>, where
        <literal>value</literal> is a legal value for <emphasis role="bold">F</emphasis> and
        <literal>subvalue1</literal>...<literal>subvalueN</literal> are legal values of some
        of <emphasis role="bold">F</emphasis>'s subfeatures. For example, the properties
        <literal>&lt;toolset&gt;gcc &lt;toolset-version&gt;3.0.1</literal> can be
        expressed more conscisely using a value-string, as
        <literal>&lt;toolset&gt;gcc-3.0.1</literal>.</para>

      <para>A <emphasis>property set</emphasis> is a set of properties (i.e. a
        collection without duplicates), for instance:
        <literal>&lt;toolset&gt;gcc &lt;runtime-link&gt;static</literal>.</para>

      <para>A <emphasis>property path</emphasis> is a property set whose elements have
        been joined into a single string separated by slashes. A property
        path representation of the previous example would be
        <literal>&lt;toolset&gt;gcc/&lt;runtime-link&gt;static</literal>.</para>

      <para>A <emphasis>build specification</emphasis> is a property set that fully
        describes the set of features used to build a target.</para>

      <section id="bbv2.reference.features.validity">
        <title>Property Validity</title>

        <para>
          For <link linkend=
            "bbv2.reference.features.attributes.free">free</link>
            features, all values are valid. For all other features,
          the valid values are explicitly specified, and the build
          system will report an error for the use of an invalid
          feature-value. Subproperty validity may be restricted so
          that certain values are valid only in the presence of
          certain other subproperties. For example, it is possible
          to specify that the <code>&lt;gcc-target&gt;mingw</code>
          property is only valid in the presence of
          <code>&lt;gcc-version&gt;2.95.2</code>.
        </para>

      </section>
      <section id="bbv2.reference.features.attributes">
        <title>Feature Attributes</title>

        <para>Each feature has a collection of zero or more of the following
          attributes. Feature attributes are low-level descriptions of how the
          build system should interpret a feature's values when they appear in
          a build request. We also refer to the attributes of properties, so
          that an <emphasis>incidental</emphasis> property, for example, is
          one whose feature has the <emphasis>incidental</emphasis>
          attribute.</para>

        <itemizedlist>
          <listitem>
            <para><emphasis>incidental</emphasis></para>

            <para>Incidental features are assumed not to affect build
              products at all. As a consequence, the build system may use
              the same file for targets whose build specification differs
              only in incidental features. A feature that controls a
              compiler's warning level is one example of a likely
              incidental feature.</para>

            <para>Non-incidental features are assumed to affect build
              products, so the files for targets whose build specification
              differs in non-incidental features are placed in different
              directories as described in <xref linkend="bbv2.reference.buildprocess.targetpath"/>.
            </para>
          </listitem>

          <listitem>
            <para>
              <anchor id="bbv2.reference.features.attributes.propagated"/>
              <emphasis>propagated</emphasis>
            </para>

            <para>Features of this kind are
              propagated to dependencies. That is, if a <link linkend=
                "bbv2.overview.targets.main">main target</link> is built using a
              propagated
              property, the build systems attempts to use the same property
              when building any of its dependencies as part of that main
              target. For instance, when an optimized exectuable is
              requested, one usually wants it to be linked with optimized
              libraries. Thus, the <literal>&lt;optimization&gt;</literal> feature is
              propagated.</para>
          </listitem>

          <listitem>
            <para>
              <anchor id="bbv2.reference.features.attributes.free"/>
              <emphasis>free</emphasis>
            </para>

            <para>Most features have a finite set of allowed values, and can
              only take on a single value from that set in a given build
              specification. Free features, on the other hand, can have
              several values at a time and each value can be an arbitrary
              string. For example, it is possible to have several
              preprocessor symbols defined simultaneously:</para>

<programlisting>
&lt;define&gt;NDEBUG=1 &lt;define&gt;HAS_CONFIG_H=1
</programlisting>

          </listitem>

          <listitem>
            <para><emphasis>optional</emphasis></para>

            <para>An optional feature is a feature that is not required to
              appear in a build specification. Every non-optional non-free
              feature has a default value that is used when a value for
              the feature is not otherwise specified, either in a target's
              requirements or in the user's build request. [A feature's
              default value is given by the first value listed in the
              feature's declaration. -- move this elsewhere - dwa]</para>
          </listitem>

          <listitem>
            <para><emphasis>symmetric</emphasis></para>

            <para>Normally a feature only generates a subvariant directory
              when its value differs from its default value,
              leading to an assymmetric subvariant directory structure for
              certain values of the feature. A symmetric feature
              always generates a corresponding
              subvariant directory.</para>
          </listitem>

          <listitem>
            <para><emphasis>path</emphasis></para>

            <para>The value of a path feature specifies a path. The path is
              treated as relative to the directory of Jamfile where path
              feature is used and is translated appropriately by the build
              system when the build is invoked from a different
              directory</para>
          </listitem>

          <listitem>
            <para><emphasis>implicit</emphasis></para>

            <para>Values of implicit features alone identify the feature.
              For example, a user is not required to write
              "&lt;toolset&gt;gcc", but can simply write "gcc". Implicit
              feature names also don't appear in variant paths, although
              the values do. Thus: bin/gcc/... as opposed to
              bin/toolset-gcc/.... There should typically be only a few
              such features, to avoid possible name clashes.</para>
          </listitem>

          <listitem>
            <para><emphasis>composite</emphasis></para>

            <para>Composite features actually correspond to groups of
              properties. For example, a build variant is a composite
              feature. When generating targets from a set of build
              properties, composite features are recursively expanded and
              <emphasis>added</emphasis> to the build property set, so rules can find
              them if necessary. Non-composite non-free features override
              components of composite features in a build property set.</para>
          </listitem>

          <listitem>
            <para><emphasis>dependency</emphasis></para>

            <para>The value of a dependency feature is a target reference.
              When used for building of a main target, the value of
              dependency feature is treated as additional dependency.</para>

            <para>For example, dependency features allow to state that
              library A depends on library B. As the result, whenever an
              application will link to A, it will also link to B.
              Specifying B as dependency of A is different from adding B to
              the sources of A. <!-- Need to clarify this. --></para>
          </listitem>
        </itemizedlist>

        <para>Features that are neither free nor incidental are called
          <emphasis>base</emphasis> features.</para>


      </section>
      <section id="bbv2.reference.features.declaration">
        <title>Feature Declaration</title>

        <para>The low-level feature declaration interface is the
          <literal>feature</literal> rule from the
          <literal>feature</literal> module:

<programlisting>
rule feature ( name : allowed-values * : attributes * )
</programlisting>

          A feature's allowed-values may be extended with the
          <code>feature.extend</code> rule.
        </para>

      </section>
    </section>

    <section id="bbv2.reference.variants.proprefine">
      <title>Property refinement</title>

      <para>When a target with certain properties is requested, and that
        target requires some set of properties, it is needed to find the
        set of properties to use for building. This process is called
        <emphasis>property refinement</emphasis> and is performed by these rules</para>

      <orderedlist>

        <listitem>
          <simpara>
            Each property in the required set is added to the original
            property set
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            If the original property set includes property with a different
            value of non free feature, that property is removed.
          </simpara>
        </listitem>
      </orderedlist>
    </section>

    <section id="bbv2.reference.variants.propcond">
      <title>Conditional properties</title>

      <para>Sometime it's desirable to apply certain requirements only for
        a specific combination of other properties. For example, one of
        compilers that you use issues a pointless warning that you want to
        suppress by passing a command line option to it. You would not
        want to pass that option to other compilers. Conditional
        properties allow you to do just that. Their syntax is:</para>

      <programlisting>
        property ( "," property ) * ":" property
      </programlisting>

      <para>
        For example, the problem above would be solved by:

<programlisting>
exe hello : hello.cpp : &lt;toolset&gt;yfc:&lt;cxxflags&gt;-disable-pointless-warning ;
</programlisting>
      </para>

      <para>The syntax also allows several properties in the condition, for
        example:
<programlisting>
exe hello : hello.cpp : &lt;os&gt;NT,&lt;toolset&gt;gcc:&lt;link&gt;static ;
</programlisting>
      </para>

    </section>

    <section id="bbv2.reference.ids">
      <title>Target identifiers and references</title>

      <para><emphasis>Target identifier</emphasis> is used to denote a
        target. The syntax is:</para>

<programlisting>
target-id -&gt; (project-id | target-name | file-name )
              | (project-id | directory-name) "//" target-name
project-id -&gt; path
target-name -&gt; path
file-name -&gt; path
directory-name -&gt; path
</programlisting>

      <para>
        This grammar allows some elements to be recognized as either

        <itemizedlist>
          <listitem>
            <simpara>
              project id (at this point, all project ids start with slash).
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              name of target declared in current Jamfile (note that target
              names may include slash).
            </simpara>
          </listitem>

          <listitem>
            <simpara>
              a regular file, denoted by absolute name or name relative to
              project's sources location.
            </simpara>
          </listitem>
        </itemizedlist>

        To determine the real meaning a check is made if project-id
        by the specified name exists, and then if main target of that
        name exists. For example, valid target ids might be:

<screen>
a                                    -- target in current project
lib/b.cpp                            -- regular file
/boost/thread                        -- project "/boost/thread"
/home/ghost/build/lr_library//parser -- target in specific project
</screen>

      </para>

      <para><emphasis role="bold">Rationale:</emphasis>Target is separated from project by special
        separator (not just slash), because:</para>

      <itemizedlist>
        <listitem>
          <simpara>
            It emphasises that projects and targets are different things.
          </simpara>
        </listitem>

        <listitem>
          <simpara>
            It allows to have main target names with slashes.

            <!-- The motivation for which is:

            So, to summarize:

            1. The project that extract tarfile may extract all possible kinds
            of targets, and it's reasonable to use them directly from other
            project.

            2. The rule for unpacking tar is inplemented in terms of
            "patch-file", for maintainability, and therefore, must use main
            target name that contains slashes?

            3. Using sub-Jamfile in "foo" to declare extracted file "foo/b" is
            not an option, because you should not change existing tree

            That makes good rationale for why main target must contain names.
            -->
          </simpara>
        </listitem>
      </itemizedlist>

      <para id="bbv2.reference.targets.references">
        <emphasis>Target reference</emphasis> is used to
        specify a source target, and may additionally specify desired
        properties for that target. It has this syntax:</para>

<programlisting>
target-reference -&gt; target-id [ "/" requested-properties ]
requested-properties -&gt; property-path
</programlisting>

      <para>
        For example,

        <programlisting>
          exe compiler : compiler.cpp libs/cmdline/&lt;optimization&gt;space ;
        </programlisting>

        would cause the version of <literal>cmdline</literal> library,
        optimized for space, to be linked in even if the
        <literal>compiler</literal> executable is build with optimization for
        speed.
      </para>
    </section>

  </section>

</chapter>

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