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<!DOCTYPE html>
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<head>
  <title>FCM: User Guide: FCM Make</title>
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    <h1>FCM: User Guide: FCM Make</h1>
  </div>

  <div class="container">
  <div class="row">
  <div class="col-md-12">

  <h2 id="introduction">Introduction</h2>

  <p>The FCM make system provides a common environment for running the extract
  system, build system, and other utilities. Simply put, it controls a chain of
  steps. It is NOT to be confused with the standard Unix utility
  <code>make</code>.</p>

  <p>See <a href="annex_cfg.html#make">Annex: FCM Configuration File &gt; FCM
  Make Configuration</a> for a full list of declarations in an FCM Make
  configuration file.</p>

  <h2 id="concept">FCM Make Concept</h2>

  <h3 id="concept.cli">FCM Make Concept: Command Line Interface</h3>

  <p>The FCM make system can be invoked using the command line interface:</p>
  <pre>
fcm make [OPTIONS] [DECLARAION ...]
</pre>

  <p>The FCM make system relies on a configuration file to tell it what to do.
  It looks for configurations with the following logic:</p>

  <ol>
    <li>It reads each configuration file specified using the
    <code>--config-file=PATH</code> option in the order they are
    specified.</li>
    
    <li>If the <code>--config-file=PATH</code> option is not specified, it will
    attempt to read <code>fcm-make.cfg</code> if it exists.</li>

    <li>It looks at the current working directory, or the directory specified
    in the <code>--directory=PATH</code> option for configuration files
    specified as relative paths.</li>

    <li>If one or more <code>--config-file-path=PATH</code> option is
    specified, it also searches for configuration files under the specified
    values, in the order the options are specified.</li>

    <li>Finally, each <var>KEY=VALUE</var> command line argument is considered
    a configuration declaration line.</li>
  </ol>

  <p>For details of the other command line options please see <a href=
  "command_ref.html#fcm-make">FCM Command Reference &gt; fcm make</a>.</p>

  <h3 id="concept.cfg">FCM Make Concept: Configuration File</h3>

  <p>The FCM make configuration file is expected to be an FCM configuration
  file. (See <a href="annex_cfg.html">Annex: FCM Configuration File</a>.) A
  typical FCM make configuration file may look like:</p>
  <pre>
steps = extract build                           # 1

extract.ns = egg ham bacon                      # 2
# ... more extract configuration

build.target = egg.exe ham.exe bacon            # 3
# ... more build configuration
</pre>

  <p>At point 1, the <code><a href="annex_cfg.html#make.steps">steps</a></code>
  declaration tells the system to invoke two steps. Their IDs are
  <samp>extract</samp> and <samp>build</samp>, both are IDs for built-in
  systems. (The other 2 being <samp>mirror</samp> and <samp>preprocess</samp>.)
  Each step has its own declarations, which are prefixed with the step ID and a
  full stop. The declarations at point 2 are used by the logic for running the
  <samp>extract</samp> step and the declarations at point 3 are used by the
  logic for running the <samp>build</samp> step.</p>

  <p>There are times when you may need to invoke the same system (e.g. the
  build system) in slightly different configurations. To do this you need to
  use the <code><a href="annex_cfg.html#make.step.class">step.class</a></code>
  declaration to define custom step IDs for each build. E.g.:</p>
  <pre>
step.class[build-this build-that] = build       # 1
steps = extract build-this build-that           # 2

extract.ns = egg ham bacon                      # 3
# ... more extract configuration

build-this.prop{fc.defs} = DEFS TO BUILD THIS   # 4
build-this.target = this.exe
# ... more build configuration for "build-this"

build-that.prop{fc.defs} = DEFS TO BUILD THAT   # 5
build-that.target = that.exe
# ... more build configuration for "build-that"
</pre>

  <p>At point 1, we define the IDs <samp>build-this</samp> and
  <samp>build-that</samp> to be an instance of the <samp>build</samp> class. At
  point 2, we tell the system to run <samp>extract</samp>, then
  <samp>build-this</samp>, then <samp>build-that</samp>. At point 4 and 5, we
  define the configurations for <samp>build-this</samp> and
  <samp>build-that</samp> respectively.</p>

  <h3 id="concept.use">FCM Make Concept: Inheritance</h3>

  <p>The FCM Make system allows inheritance of configuration and files from
  succeeded makes, so the current make does not have to re-do everything that
  may already be available else where. To do this, specify the inheritance with
  a <code><a href= "annex_cfg.html#make.use">use</a> declaration</code>,
  e.g.:</p>

  <pre>
use = /path/to/succeeded/make/
</pre>

  <p>For more information on how an inheritance behaves, see:</p>

  <ul>
    <li><a href="#extract.inherit">Extract Inheritance</a></li>

    <li><a href="#build.inherit">Build Inheritance</a></li>
  </ul>

  <h3 id="concept.dest">FCM Make Concept: Directory Structure</h3>

  <p>When you run <code>fcm make</code>, it will create a directory
  structure that may look like:</p>

  <pre>
.fcm-make/...
extract/...
build/...
...
</pre>

  <p>Each normal sub-directory, such as <samp>extract/</samp> and
  <samp>build/</samp>, contains the result of each step. The hidden
  sub-directory <samp>.fcm-make/</samp> is used by <code>fcm make</code> as a
  working area. It may contain the following items:</p>

  <dl>
    <dt><samp>.fcm-make/cache/</samp></dt>

    <dd>An area for caching non-local items. E.g. the extract system exports
    source trees from the version control system into this cache. If <code>fcm
    make</code> is invoked with the <code>--archive</code> option, contents in
    this directory will be compressed into TAR-GZIP files, e.g.
    <samp>.fcm-make/cache/extract/</samp> will become
    <samp>.fcm-make/cache/extract.tar.gz</samp>.</dd>

    <dt><samp>fcm-make-as-parsed.cfg -&gt;
    .fcm-make/config-as-parsed.cfg</samp></dt>

    <dd>The configuration file as parsed by the latest <code>fcm make</code>
    command at this destination.</dd>

    <dt><samp>fcm-make-on-success.cfg -&gt;
    .fcm-make/config-on-success.cfg</samp></dt>

    <dd>The configuration file that can be used to repeat the latest successful
    <code>fcm make</code> command at this destination.</dd>

    <dt><samp>.fcm-make/ctx.gz</samp></dt>
    
    <dd>A serialised data structure that represents the context of the latest
    <code>fcm make</code> command at this destination.  It is a
    <code>gzip</code> file containing data in the <a
    href="http://perldoc.perl.org/Storable.html">Perl Storable</a> format.</dd>

    <dt><samp>fcm-make.log -&gt; .fcm-make/log</samp></dt>
    
    <dd>A diagnostic log generated by the latest <code>fcm make</code> command
    at this destination. The content should be equivalent to the diagnostic
    output in STDOUT and STDERR at <code>-vv</code> verbosity.</dd>
  </dl>

  <h3 id="concept.name">FCM Make Concept: Context Name</h3>

  <p>You may sometimes need to run <code>fcm make</code> in the same location of
  the file system. Perhaps you are on a network with a shared file system, but
  only certain tools are available on different hosts, e.g. you can only extract
  on one host and build on a different host, you should name the makes so that
  they don't end up overwriting each other's context, logs and other
  outputs. To do so, you can use the <code>--name=NAME</code> option on the
  command line, and/or the <a href="annex_cfg.html#make.name">name</a>
  declaration in the configuration file. Using <code>--name=2</code> as an
  example, you will get the following:</p>

  <ul>
    <li>The command will search for <code>fcm-make2.cfg</code> instead of
    <code>fcm-make.cfg</code>.</li>

    <li>The command will dump context, logs, etc with file names such as
    <samp>.fcm-make2/*</samp>, <samp>fcm-make2-as-parsed.cfg</samp>,
    <samp>fcm-make2.log</samp>, etc.</li>

    <li>The command will only allow inheritance from a location where a
    successful make with the same name exists.</li>
  </ul>

  <h2 id="extract">Extract</h2>

  <p>The extract system provides an interface between the version control
  system (currently Subversion) and the build system. Where appropriate, it
  extracts code and combines changes from the repositories and other
  user-defined locations to a directory tree suitable for feeding into the build
  system.</p>

  <p>The extract system supports the <code>--jobs=N</code> option of the
  <code>fcm make</code> command. It uses <var>N</var> child processes to get
  source trees information and to export source trees from their repositories in
  parallel.</p>

  <h3 id="extract.basic">Extract: Basic</h3>

  <p>The following is an example of how to extract the source trees from a file
  system path and the trunks of 2 known projects (version controlled in
  Subversion repositories with a standard FCM layout):</p>
  <pre>
steps = extract                    # line 1
extract.ns = ops var um            # line 2
extract.location[ops] = $HOME/ops  # line 3
</pre>

  <p>Here is an explanation of what each line does:</p>

  <ul>
    <li><dfn>line 1</dfn>: the <code><a href=
    "annex_cfg.html#make.steps">steps</a></code> declaration tells the make
    system to invoke the extract system.</li>

    <li><dfn>line 2</dfn>: the <code><a href=
    "annex_cfg.html#make.extract.ns">extract.ns</a></code> declaration is used
    to specify a space delimited list of names of the projects to extract.</li>

    <li><dfn>line 3</dfn>: the <code><a href=
    "annex_cfg.html#make.extract.location">extract.location</a></code>
    declaration is used to specify the base source tree of a project
    (<samp>ops</samp> in this case) to extract. The value of the declaration
    can be a path in the file system or a location in a version control system.
    In this case, the declaration specifies the base source tree of the
    <samp>ops</samp> project to be a path in the file system at
    <samp>$HOME/ops</samp>. If the base source tree of a specified project
    name-space is not declared, the system will make an assumption. For a
    project hosted in a Subversion repository, the system will assume
    <samp>trunk@HEAD</samp> if the project URL is registered in the keyword
    configuration file or with the <code><a href=
    "annex_cfg.html#make.extract.location.primary">extract.location{primary}</a></code>
    declaration (see below).</li>
  </ul>

  <p>If you save this file as <samp>fcm-make.cfg</samp> and invoke the
  <code>fcm make</code> command you should end up with a source tree in the
  current working directory that looks like (hidden path not shown):</p>
  <pre>
extract/ops/...
extract/um/...
extract/var/...
</pre>

  <p>The result of the extract can be found in the <samp>extract/</samp>
  sub-directory. Note: The generated source tree will not contain any symbolic
  links or hidden files (e.g. file names beginning with a <samp>.</samp>),
  because the extract system ignores them.</p>

  <div class="well">
    <p><strong><span class="glyphicon glyphicon-pencil"
    aria-hidden="true"></span> Note - project name-space and
    location</strong></p>

    <p>Whoever installed FCM at your site would have defined the name-spaces
    and the locations of the common projects at your site using the keyword
    configuration file at <samp>$FCM/etc/fcm-keyword.cfg</samp> (where
    <samp>$FCM/bin</samp> is the path at which FCM is installed).
    Alternatively, users can define their own set of project name-spaces and
    their locations using <samp>$HOME/.metomi/fcm/keyword.cfg</samp>. For
    information on keyword configuration files, please refer to <a href=
    "system_admin.html#fcm-keywords">System Administration &gt; FCM
    keywords</a>. If a project name-space is not defined in a keyword
    configuration, it can be defined in the FCM make configuration using the
    <code><a href=
    "annex_cfg.html#make.extract.location.primary">extract.location{primary}</a></code>
    declaration. E.g. to define the location of the <samp>foo</samp> project,
    you can do: <samp>extract.location{primary}[foo] =
    svn://server/repos/foo</samp>.</p>
  </div>

  <div class="well">
    <p><strong><span class="glyphicon glyphicon-pencil"
    aria-hidden="true"></span> Note - incremental mode</strong></p>

    <p>Suppose you have already invoked <code>fcm make</code> using the above
    configuration file. At a later time, you have made some changes to some of
    the files in the source trees. Re-running <code>fcm make</code> on the same
    configuration will trigger the incremental mode. In the incremental mode,
    the extract system will update only those files that are modified. If the
    last modified time (or last commit revision) of a source file in the
    current extract differs from that in the previous extract, the system will
    attempt a content comparison. The system updates the destination only if
    the content and/or file access permission of the source differs from that
    of the destination. To avoid the incremental mode and start afresh, invoke
    <code>fcm make</code> with the <code>--new</code> option.</p>
  </div>

  <h3 id="extract.location-types">Extract: Location Types</h3>

  <p>The extract system currently supports the following location types:</p>

  <dl class="dl-horizontal">
    <dt>fs</dt>

    <dd>A readable location in the local file system. E.g.
    <code>~/my-project</code>, <code>/home/lily/my-project</code>, etc.</dd>

    <dt>ssh</dt>

    <dd>A readable location in the file system of a remote host accessible via
    <code>ssh</code> and <code>rsync</code>, specified in the form
    <var>[USER@]HOST:PATH</var>. The <code>ssh</code> access must be
    without a password, and you must be able to run the <a href=
    "http://www.gnu.org/software/coreutils/">GNU coreutils</a> version of the
    <code>find</code> and <code>stat</code> on the remote host. E.g.
    <code>mylinuxbox:my-project</code>,
    <code>holly@hpc:/data/holly/my-project</code>.</dd>

    <dt>svn</dt>

    <dd>A Subversion location, which may be a working copy or a valid Subversion
    URL. Supported URL schemes are: <code>file</code>, <code>http</code>,
    <code>https</code>, <code>svn</code> and <code>svn+ssh</code>. E.g.
    <code>svn://mysvnhost/my-project/trunk@40778</code>,
    <code>~/my-project@32734</code>.</dd>
  </dl>

  <p>See also <a href=
  "annex_cfg.html#make.extract.location">extract.location</a>.</p>

  <h3 id="extract.path-root">Extract: Redefine the Root of the Source Tree of a
  Project</h3>

  <p>Consider a project called <samp>foo</samp> with a source tree that looks
  like:</p>
  <pre>
doc/...
src/bar/...
src/baz/...
</pre>

  <p>Suppose you are only interested in the contents of the <samp>src/</samp>
  sub-tree. You can specify the root of the extract using the <code><a href=
  "annex_cfg.html#make.extract.path-root">extract.path-root</a></code>
  declaration. E.g.:</p>
  <pre>
steps = extract              # line 1
extract.ns = foo             # line 2
extract.path-root[foo] = src # line 3
</pre>

  <p>Running <code>fcm make</code> with this configuration should give a source
  tree that looks like (hidden path not shown):</p>
  <pre>
extract/foo/bar/...
extract/foo/baz/...
</pre>

  <h3 id="extract.path-filter">Extract: Filter the Paths in the Source Tree of
  a Project</h3>

  <p>Going back to the above source tree in the <samp>foo</samp> project,
  imagine the <samp>src/bar/</samp> sub-directory contains:</p>
  <pre>
src/bar/wine/red.c
src/bar/wine/rose.c
src/bar/wine/white.c
src/bar/...
</pre>

  <p>If you do not want <samp>src/bar/wine/rose.c</samp> in the extract, you
  can ask for it to be excluded using the <code><a href=
  "annex_cfg.html#make.extract.path-excl">extract.path-excl</a></code>
  declaration. E.g.:</p>
  <pre>
steps = extract                          # line 1
extract.ns = foo
extract.path-root[foo] = src             # line 3
extract.path-excl[foo] = bar/wine/rose.c # line 4
</pre>

  <p>Note: Because the root is redefined in line 3, the path in the
  <code><a href=
  "annex_cfg.html#make.extract.path-excl">extract.path-excl</a></code>
  declaration in line 4 is declared from the new root level.</p>

  <p>Running <code>fcm make</code> with this configuration should give a source
  tree that looks like (hidden path not shown):</p>
  <pre>
extract/foo/bar/wine/red.c
extract/foo/bar/wine/white.c
extract/foo/bar/...
extract/foo/baz/...
</pre>

  <p>On the other hand, if you only want <samp>src/bar/wine/rose.c</samp> in
  the extract, you can ask the system to exclude everything in
  <samp>src/bar/wine/</samp> but include <samp>src/bar/wine/rose.c</samp> using
  the <code><a href=
  "annex_cfg.html#make.extract.path-incl">extract.path-incl</a></code>
  declaration. E.g.:</p>
  <pre>
steps = extract                          # line 1
extract.ns = foo                         # line 2
extract.path-root[foo] = src             # line 3
extract.path-excl[foo] = bar/wine        # line 4
extract.path-incl[foo] = bar/wine/rose.c # line 5
</pre>

  <p>Running <code>fcm make</code> with this configuration should give a source
  tree that looks like (hidden path not shown):</p>
  <pre>
extract/foo/bar/wine/rose.c
extract/foo/bar/...
extract/foo/baz/...
</pre>

  <h3 id="extract.location-diff">Extract: Combining Changes from Multiple
  Branches of a Project</h3>

  <p>We have so far only dealt with extracts from a single base source tree in
  each project. The extract system can also be used to <em>combine</em> changes
  from different source trees (against a base source tree) of a project.</p>

  <p>E.g. consider a project called <samp>food</samp>. In the latest release
  (<samp>trunk@3739</samp>), the source tree looks like this:</p>
  <pre>
doc/...
src/egg/boiled.y
src/egg/microwave.x
src/egg/omelette.c
src/egg/poached.f90
src/...
</pre>

  <p>Jamie, Gordon and Rick are all developing changes against the latest
  release of the project.</p>

  <p>Jamie has made the following changes (displayed using the notation of
  <code>svn status</code>) in his branch at
  <samp>branches/dev/jamie/r3739_t381@3984</samp>:</p>
  <pre>
D      src/egg/boiled.y
A      src/egg/fried.pl
M      src/egg/omelette.c
</pre>

  <p>Gordon has made the following changes in his branch at
  <samp>branches/dev/gordon/r3739_t376@3993</samp>:</p>
  <pre>
M      src/egg/omelette.c
M      src/egg/poached.f90
</pre>

  <p>Rick has made the following changes in his working copy at
  <samp>~rick/food</samp>, but has yet to commit his changes back:</p>
  <pre>
M      src/egg/boiled.y
A      src/egg/scrambled.bash
</pre>

  <p>To combine their changes in an extract, the FCM make configuration file
  should look like:</p>
  <pre id="example.extract">
steps = extract
extract.ns = food
extract.location[food] = trunk@3739
extract.location{diff}[food] = \
    branches/dev/jamie/r3739_t381@3984 \
    branches/dev/gordon/r3739_t376@3993 \
    ~rick/food
</pre>

  <p>Here we have an <code><a href=
  "annex_cfg.html#make.extract.location">extract.location</a></code>
  declaration like before. This time it is pointing to the latest release of
  the <samp>food</samp> project. The changes against the base source tree are
  declared using the <code><a href=
  "annex_cfg.html#make.extract.location.diff">extract.location{diff}</a></code>
  declaration.</p>

  <p>Invoking <code>fcm make</code> with this configuration file will result in
  a source tree that looks like (hidden file not shown):</p>
  <pre>
extract/doc/...
extract/src/egg/fried.pl
extract/src/egg/microwave.x
extract/src/egg/omelette.c
extract/src/egg/poached.f90
extract/src/egg/scrambled.bash
extract/src/...
</pre>

  <p>Note:</p>

  <ul>
    <li>There is no <samp>extract/src/egg/boiled.y</samp> file in the extract
    tree because it is deleted by Jamie's branch. Even though this file is
    modified in Rick's working copy, the extract will ignore this and assume
    that the deletion takes precedence.</li>

    <li>The <samp>extract/src/egg/fried.pl</samp> file comes from Jamie's
    branch.</li>

    <li>The <samp>extract/src/egg/microwave.x</samp> file comes from the latest
    release (base).</li>

    <li>The <samp>extract/src/egg/omelette.c</samp> file is the result of a
    merge of the changes in Jamie's and Gordon's branches. This example assumes
    that there is no conflict in the merge. If the merge results in a conflict,
    the extract will fail.</li>

    <li>The <samp>extract/src/egg/poached.f90</samp> file comes from Gordon's
    branch.</li>

    <li>The <samp>extract/src/egg/scrambled.bash</samp> file comes from Rick's
    working copy.</li>
  </ul>

  <h3 id="extract.inherit">Extract Inheritance</h3>

  <p>If a previous extract with a similar configuration exists in another
  location, it can be more efficient to inherit from this previous extract in
  your current extract. This works like a normal incremental extract, except
  that your extract will only contain the changes you have specified (compared
  with the inherited extract) instead of the full directory tree in the
  destination. This type of incremental extract is useful in several ways. For
  instance:</p>

  <ul>
    <li>It is fast, because you only have to extract files that you have
    changed.</li>

    <li>The subsequent build will also be fast, since it will act like an
    incremental build.</li>

    <li>You do not need write access to the original extract. A system
    administrator can set up a stable version in a central account, which
    developers can then inherit from.</li>

    <li>You want an incremental extract, but you need to leave the original
    extract unmodified.</li>
  </ul>

  <p>Consider the <a href="#example.extract">previous example</a>. Imagine an
  extract already exists for the latest release for the <samp>food</samp>
  project at <samp>/home/food/latest/</samp>, and now you want to test the
  changes introduced by Jamie, Gordon and Rick. You can <code><a href=
  "annex_cfg.html#make.use">use</a></code> the original extract with the
  changes:</p>
  <pre>
use = /home/food/latest
extract.location{diff}[food] = \
    branches/dev/jamie/r3739_t381@3984 \
    branches/dev/gordon/r3739_t376@3993 \
    ~rick/food
</pre>

  <p>Invoking <code>fcm make</code> with this configuration file will result in
  a source tree that looks like (hidden file not shown):</p>
  <pre>
extract/src/egg/fried.pl
extract/src/egg/omelette.c
extract/src/egg/poached.f90
extract/src/egg/scrambled.bash
</pre>

  <p>The extract will work in an incremental-like mode. The only difference is
  that the original extract at <samp>/home/food/latest/</samp> will be left
  untouched, and the new extract will contain only the changes introduced by
  the diff locations. Note that, although
  <samp>extract/src/egg/boiled.y</samp> remains in the original extract, it
  will not be used in any subsequent build step.</p>

  <dl>
    <dt>Extract inheritance limitation</dt>

    <dd>
      <p>Extract inheritance allows you to add more diff locations to a project,
      but you should not include any other declarations relating to the extract.
      Doing so is not safe and should trigger an exception.</p>

      <p>In some situations this implies that it will not be possible to use
      inherited extracts. You should use a new extract if, for instance, a new
      diff location contains a change which requires the use of source files in
      a previously excluded name-space.</p>
    </dd>
  </dl>

  <h3 id="extract.diagnostic">Extract Diagnostic</h3>

  <p>The amount of diagnostic messages generated by the extract system is
  dependent on the diagnostic verbosity level that can be modified by the
  <code>-v</code> and <code>-q</code> options to the <code>fcm make</code>
  command.</p>

  <p>The following is a list of diagnostic output at each verbosity level:</p>

  <dl>
    <dt>-q</dt>

    <dd>
      <ul>
        <li>Exceptions.</li>
      </ul>
    </dd>

    <dt>default</dt>

    <dd>
      <ul>
        <li>Everything at the -q level.</li>

        <li>Start time of the extract.</li>

        <li>The number and location of each source tree in each project. The
        base source tree is number 0. E.g.:
          <pre>
[info] location um: 0: svn://fcm2/UM_svn/UM/trunk@11732
[info] location um: 1: svn://fcm2/UM_svn/UM/branches/dev/Share/VN7.3_hg3_dust_443@11858
[info] location um: 2: svn://fcm2/UM_svn/UM/branches/dev/Share/VN7.3_hg3_ccw_precip@11857
[info] location um: 3: svn://fcm2/UM_svn/UM/branches/dev/hadco/VN7.3_HG3_porting_lsp_fixes@12029
...
</pre>
        </li>

        <li>The number of targets by their destination status and their source
        status. E.g.:
          <pre>
[info]   dest:    3 [A added]
[info]   dest:  134 [a added, overriding inherited]
[info]   dest:    6 [d deleted, overriding inherited]
[info]   dest: 2818 [U unchanged]
[info] source:    3 [A added by a diff source tree]
[info] source:    6 [D deleted by a diff source tree]
[info] source:   16 [G merged from 2+ diff source trees]
[info] source:  118 [M modified by a diff source tree]
[info] source: 2818 [U from base]
</pre>
        </li>

        <li>Total time.</li>
      </ul>
    </dd>

    <dt>-v</dt>

    <dd>
      <ul>
        <li>Everything at the default level.</li>

        <li>The destination and source status for each modified target. E.g.:
          <pre>
...
[info] aM um:0,13    atmosphere/short_wave_radiation/r2_lwrad3c.F90
[info] aG um:0,6,13  control/top_level/scm_main.F90
[info] AA um:-,8     include/constant/cnv_parc_lim.h
...
</pre>

          <p>The 2 letters following <samp>[info]</samp> is the destination
          status and the source status of the target. This is followed by the
          name-space of the project, a colon and the source tree number(s)
          providing the source for the target (in a comma separated list). This
          is then followed by the name-space of the target path. The source
          tree number <samp>0</samp> denotes the base source tree, a dash
          <samp>-</samp> in place of a <samp>0</samp> means that the source
          only exists in a diff source tree.</p>
        </li>
      </ul>
    </dd>

    <dt>-vv</dt>

    <dd>
      <ul>
        <li>Everything at the -v level.</li>

        <li>Each shell command invoked with elapsed time and return code.</li>
      </ul>
    </dd>
  </dl>

  <p>Here is an explanation of each target destination status:</p>

  <dl>
    <dt><samp>[A added]</samp></dt>

    <dd>Target newly added to the destination.</dd>

    <dt><samp>[a added, overriding inherited]</samp></dt>

    <dd>Target added to the current extract destination, i.e. modified compared
    with the target with the same name-space in an inherited extract
    destination.</dd>

    <dt><samp>[D deleted]</samp></dt>

    <dd>Target deleted from the extract destination during an incremental
    extract.</dd>

    <dt><samp>[d deleted, overriding inherited]</samp></dt>

    <dd>Target deleted from the current extract destination, i.e. a target with
    the same name-space exists in an inherited extract destination.</dd>

    <dt><samp>[M modified]</samp></dt>

    <dd>Target modified in the extract destination during an incremental
    extract.</dd>

    <dt><samp>[U unchanged]</samp></dt>

    <dd>Target unchanged compared with the previous (or any inherited)
    extract.</dd>

    <dt><samp>[? unknown]</samp></dt>

    <dd>Target does not have a destination. This destination status is normally
    associated with the <samp>[D deleted]</samp> source status.</dd>
  </dl>

  <p>Here is an explanation of each target source status:</p>

  <dl>
    <dt><samp>[A added by a diff source tree]</samp></dt>

    <dd>The source of the target comes from a diff source tree, and the base
    source tree does not have a source in the same name-space.</dd>

    <dt><samp>[D deleted by a diff source tree]</samp></dt>

    <dd>Target is deleted by a diff source tree, (i.e. exists in base source
    tree, but missing from a diff source tree).</dd>

    <dt><samp>[G merged from 2+ diff source trees]</samp></dt>

    <dd>The source of the target comes from 2 or more diff source trees, (i.e.
    the actual source is the result of a merge between all the changes).</dd>

    <dt><samp>[M modified by a diff source tree]</samp></dt>

    <dd>The source of the target comes from a diff source tree.</dd>

    <dt><samp>[U from base]</samp></dt>

    <dd>The source of the target comes from the base source tree, (i.e. the
    source is unchanged by any diff source tree).</dd>

    <dt><samp>[? unknown]</samp></dt>

    <dd>The target has no source. This source status is normally displayed in an
    incremental extract, where a target in a previous extract is not a target in
    the current extract, and is normally associated with the <samp>[D
    deleted]</samp> destination status.</dd>
  </dl>

  <h2 id="mirror">Mirror</h2>

  <p>The mirror system provides a way to mirror the results of the make steps
  to another location, where the FCM make may need to continue. It is typically
  used after an extract to set up the build on an alternate platform.</p>

  <h3 id="mirror.basic">Mirror: Basic</h3>

  <p>Consider the following example:</p>
  <pre>
steps = extract mirror                            # 1
# ... some extract declarations
mirror.target = user@somewhere:/path/in/somewhere # 2
mirror.prop{config-file.name} = -at-somewhere     # 3
mirror.prop{config-file.steps} = preprocess build # 4
# ... some preprocess declarations
# ... some build declarations
</pre>

  <p>When the system runs with this configuration, the system will mirror the
  result of the extract to the <a href=
  "annex_cfg.html#make.mirror.target">mirror.target</a>, i.e.
  <samp>somewhere:/path/in/somewhere</samp> using <code>ssh</code> and
  <code>rsync</code>.</p>
  
  <p>With the <a href=
  "annex_cfg.html#make.mirror.prop.config-file.name">config-file.name</a>
  property set at point 3 and the <a href=
  "annex_cfg.html#make.mirror.prop.config-file.steps">config-file.steps</a>
  property set at point 4, it will write a configuration file called
  <samp>fcm-make-at-somewhere.cfg</samp> with the make name set as
  <samp>-at-somewhere</samp> in the mirror target so that the
  <samp>preprocess</samp> and <samp>build</samp> steps can continue there.</p>

  <h3 id="mirror.diagnostic">Mirror Diagnostic</h3>

  <p>The amount of diagnostic messages generated by the mirror system is
  dependent on the diagnostic verbosity level that can be modified by the
  <code>-v</code> and <code>-q</code> options to the <code>fcm make</code>
  command.</p>

  <p>The following is a list of diagnostic output at each verbosity level:</p>

  <dl>
    <dt>-q</dt>

    <dd>
      <ul>
        <li>Exceptions.</li>
      </ul>
    </dd>

    <dt>default</dt>

    <dd>
      <ul>
        <li>Everything at the -q level.</li>

        <li>Start time of the mirror.</li>

        <li>The updated destination and its source.</li>

        <li>Total time.</li>
      </ul>
    </dd>

    <dt>-v</dt>

    <dd>
      <ul>
        <li>Everything at the default level.</li>
      </ul>
    </dd>

    <dt>-vv</dt>

    <dd>
      <ul>
        <li>Everything at the -v level.</li>

        <li>Each shell command invoked with elapsed time and return code.</li>
      </ul>
    </dd>
  </dl>

  <h2 id="build">Build</h2>

  <p>The build system performs actions on a set of source files using its
  predefined logic and the properties specified in the configuration. For
  example, it will attempt to create a binary executable for a source file
  containing a Fortran program.</p>

  <p>The build system supports the <code>--jobs=N</code> option of the <code>fcm
  make</code> command. It uses <var>N</var> child processes to analyse the
  source files and to update the targets in parallel.</p>

  <h3 id="build.basic">Build: Basic</h3>

  <p>Consider a source tree at <samp>$HOME/my-source-tree/</samp> containing
  some Fortran source files including at least one with a main program (and
  maybe other supported types of source files), you can set up an FCM make
  configuration file to build an executable. E.g.:</p>
  <pre>
steps = build
build.target{task} = link
build.source = $HOME/my-source-tree
</pre>

  <p>In this simple 3 line configuration, the <code><a href=
  "annex_cfg.html#make.steps">steps</a></code> declaration tells the make
  system to invoke the build system, the <code><a href=
  "annex_cfg.html#make.build.target">build.target</a></code> declaration tells
  the system to build any targets which require linking (i.e. any main
  programs), and the <code><a href=
  "annex_cfg.html#make.build.source">build.source</a></code> declaration
  specifies the location of the source tree.</p>

  <p>If you save this file as <samp>fcm-make.cfg</samp> and invoke the
  <code>fcm make</code> command it should attempt to build the source tree in
  the current working directory, using the default properties. If the default
  Fortran compiler <samp>gfortran</samp> is installed, and nothing goes wrong,
  you will end up with a directory tree that looks like (hidden path not
  shown):</p>
  <pre>
build/bin/...
build/include/...
build/o/...
</pre>

  <p>The result of the build can be found in the sub-directories of the
  <samp>build/</samp> sub-directory. Each <samp>build/*/</samp> sub-directory
  contains a category of targets:</p>

  <dl>
    <dt id="build.category.bin"><samp>bin</samp></dt>

    <dd>e.g. executable binary and script.</dd>

    <dt id="build.category.etc"><samp>etc</samp></dt>

    <dd>e.g. data files.</dd>

    <dt id="build.category.include"><samp>include</samp></dt>

    <dd>e.g. include files and Fortran module definition files.</dd>

    <dt id="build.category.lib"><samp>lib</samp></dt>

    <dd>e.g. object archives.</dd>

    <dt id="build.category.o"><samp>o</samp></dt>

    <dd>e.g. object files</dd>
  </dl>

  <p>Sub-directories are only created as necessary, so you may not find all of
  the above in your destination tree.</p>

  <p>If <code>fcm make</code> is invoked with the <code>--archive</code> option,
  sub-directories in categories containing intermediate build files (or any
  category specified in the
  <a href="annex_cfg.html#make.build.prop.archive-ok-target-category">
  archive-ok-target-category</a>
  property) will be put into TAR-GZIP files. E.g. with the default setting,
  <samp>include/</samp> and <samp>o/</samp> will become
  <samp>include.tar.gz</samp> and <samp>o.tar.gz</samp> respectively.</p>

  <p>To use a different compiler and/or compiler options for Fortran/C/C++, you
  use the <a href="annex_cfg.html#make.build.prop">build.prop</a> declaration to
  redefine the build properties. E.g.:</p>
  <pre>
steps = build
build.target{task} = link
build.source = $HOME/my-source-tree

# Set Fortran compiler/linker
build.prop{fc} = ifort
# Set Fortran compiler options
build.prop{fc.flags} = -i8 -r8 -O3
# Add include paths to Fortran compiler
build.prop{fc.include-paths} = /a/path/to/include /more/path/to/include
# Set link libraries for Fortran executables
build.prop{fc.lib-paths} = /path/to/my-lib
build.prop{fc.libs} = mine
# Set C compiler/linker
build.prop{cc} = icc
# Set C compiler options
build.prop{cc.flags} = -O3
# Set C++ compiler options
build.prop{cxx.flags} = -O2
# Set link libraries for C executables
build.prop{cc.lib-paths} = /path/to/my-lib /path/to/your-lib
build.prop{cc.libs} = mine yours
# Set linker, if compiler cannot be used as linker
#build.prop{ld} = ld
</pre>

  <h3 id="build.source-locations">Build Source Locations</h3>

  <p>The build system locates its source files from various places,
  including:</p>

  <ul>
    <li>Inherited locations. (See <a href="#build.inherit">Build
    Inheritance</a>.)</li>

    <li>Usable target locations of previous steps in the make. E.g. targets of
    an extract step, and <samp><a href=
    "#preprocess.category.src">src</a></samp> category targets of a preprocess
    step can both be source files of the build system. The <code><a href=
    "annex_cfg.html#make.build.prop.no-step-source">build.prop{no-step-source}</a></code>
    declaration can be used to switch off this behaviour.</li>

    <li>Locations specified by the <code><a href=
    "annex_cfg.html#make.build.source">build.source</a></code> declaration.
    Note: If you assign a relative path to the <code><a href=
    "annex_cfg.html#make.build.source">build.source</a></code> declaration, the
    system will assume the path to be relative to the make destination (not the
    current working directory, unless they happen to be the same).</li>
  </ul>

  <p>There are situations when it may not be desirable to consider every source
  file in a build. You can apply filters by source file name-spaces using the
  <code><a href="annex_cfg.html#make.build.ns-excl">build.ns-excl</a></code>
  and <code><a href=
  "annex_cfg.html#make.build.ns-incl">build.ns-incl</a></code> declarations.
  E.g.:</p>
  <pre>
# To include items in "foo" and "bar/baz" only
build.ns-excl = /              # exclude everything ...
build.ns-incl = foo bar/baz    # but include items from these name-spaces
</pre>

  <h3 id="build.source-ns">Build Source Name-spaces and Properties</h3>

  <p>Each source file is assigned a name-space (which is used to fine tune the
  build properties, such as the compiler flags). If the source file is a target
  of an extract, the name-space will be the same as the extract target (the
  relative path of the <samp>extract/</samp> sub-directory in the make
  destination). If the source file is a file in a source tree specified by
  <code><a href="annex_cfg.html#make.build.source">build.source</a></code>, the
  name-space is the relative path to the specified value. The <code><a href=
  "annex_cfg.html#make.build.source">build.source</a></code> declaration also
  accepts an optional name-space, in which case the name-space of each source
  file in the tree will be prefixed with the specified name-space. Suppose you
  have a source tree in <samp>$HOME/food</samp>:</p>
  <pre>
$HOME/food/egg.c
$HOME/food/ham.f90
</pre>

  <p>If you specify the source tree with <samp>build.source =
  $HOME/food</samp>, then <samp>$HOME/food/egg.c</samp> will be given the
  name-space <samp>egg.c</samp> and <samp>$HOME/food/ham.f90</samp> will be
  given the name-space <samp>ham.f90</samp>.</p>

  <p>On the other hand, if you specify the source tree with
  <samp>build.source[food] = $HOME</samp>, then
  <samp>$HOME/food/egg.c</samp> will be given the name-space
  <samp>food/egg.c</samp> and <samp>$HOME/food/ham.f90</samp> will be given the
  name-space <samp>food/ham.f90</samp>.</p>

  <p>The name-space is organised in a simple hierarchy. For instance, the
  <samp>foo/bar/egg</samp> name-space belongs to <samp>foo/bar</samp>, which
  belongs to <samp>foo</samp>, which belongs to the root name-space. (The root
  name-space is either an empty string or a <samp>/</samp>.)</p>

  <p>For instance, you can set the flags of the Fortran compiler using the
  <code><a href=
  "annex_cfg.html#make.build.prop.fc.flags">build.prop{fc.flags}</a></code>
  declaration at different name-space levels:</p>
  <pre>
# The global Fortran compiler flags
build.prop{fc.flags} = -O3

# The Fortran compiler flags for the "food" name-space
build.prop{fc.flags}[food] = -O2 -i8 -r8

# The Fortran compiler flags for a source file
build.prop{fc.flags}[food/bacon.f90] = -O0 -g -C
</pre>

  <h3 id="build.source-types">Build Source Types</h3>

  <p>Before the build system can do anything with its source files, it needs to
  know what they are. It determines the type of each source file by looking at
  its file name extension, then the file name itself, and then the
  <code>#!</code> line for a text file. Source files without a type are treated
  as data files.</p>

  <p>The following types are associated with file extensions:</p>

  <dl>
    <dt><a href="annex_cfg.html#make.build.prop.file-ext.c">c</a> (C source
    file)</dt>

    <dd>.c .i .m .mi</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.cxx">cxx</a> (C++
    source file)</dt>

    <dd>.cc .cp .cxx .cpp .CPP .c++ .C .mm .M .mii</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.fortran">fortran</a>
    (Fortran source file)</dt>

    <dd>.F .FOR .FTN .F90 .F95 .f .for .ftn .f90 .f95 .inc</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.h">h</a> (Preprocessor
    header file)</dt>

    <dd>.h</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.script">script</a>
    (script in various languages)</dt>

    <dd>(empty)</dd>
  </dl>

  <p>The <code>prop{file-ext.type} = extensions</code> declaration can be used
  to modify the extensions associated with a type. E.g. if you need to add
  <samp>.fort</samp> as a file extension for a Fortran source file, you can
  do:</p>
  <pre>
build.prop{file-ext.fortran} = .F .FOR .FORT .FTN .F90 .F95 \
                               .f .for .fort .ftn .f90 .f95 .inc
</pre>

  <p>You can associate file names to some file types using a
  <code>prop{file-pat.type} = regular-expression</code> declaration. E.g. if
  you have executable scripts in the source tree with no <code>#!</code> lines
  but are recognised by a <samp>*Scr_*</samp> pattern of their file names, you
  can specify a regular expression to match their file names using the <a href=
  "annex_cfg.html#make.build.prop.file-pat.script">file-pat.script</a>
  property:</p>
  <pre>
build.prop{file-pat.script} = (?msx-i:\w+Scr_\w+)
</pre>

  <p>All other text files with a <code>#!</code> line are recognised as scripts
  by the build system.</p>

  <h3 id="build.source-analysis">Build Source Analysis</h3>

  <p>Each source file with a known type (that is not ignored) is analysed by
  the build system for dependencies and other information. Here is a list of
  what the system looks for in each type of file:</p>

  <dl>
    <dt>c and cxx</dt>

    <dd>
      <p><dfn>main program</dfn>: e.g. <samp>int main()</samp>.</p>

      <p><dfn>dependency on include</dfn>: e.g. <samp>#include
      "name.h"</samp>.</p>

      <p><dfn>dependency on object</dfn>: e.g. <samp>/* depends on: name.o
      */</samp> (for <a href="#build.source-analysis.legacy">legacy
      support</a>).</p>
    </dd>

    <dt>fortran</dt>

    <dd>
      <p><dfn>main program</dfn>: e.g. <samp>program name</samp>.</p>

      <p><dfn>list of symbols</dfn>: i.e. names of top level program units
      including blockdata, function, module, program and subroutine.</p>

      <p><dfn>dependency on include</dfn>: e.g. <samp>#include "name.h"</samp>
      and <samp>include 'name.f90'</samp>.</p>

      <p><dfn>dependency on module</dfn>: e.g. <samp>use name</samp>.</p>

      <p><dfn>dependency on object</dfn>: e.g. <samp>! depends on:
      name.o</samp> (for <a href="#build.source-analysis.legacy">legacy
      support</a>).</p>
    </dd>

    <dt>h</dt>

    <dd>
      <p><dfn>dependency on include</dfn>: e.g. <samp>#include
      "file-name"</samp> (and <samp>include 'file-name'</samp> for <a href=
      "#build.source-analysis.legacy">legacy support</a>).</p>
    </dd>

    <dt>script</dt>

    <dd>
      <p><dfn>dependency on executable</dfn>: e.g. <samp># calls: name</samp>
      (for <a href="#build.source-analysis.legacy">legacy support</a>).</p>
    </dd>
  </dl>

  <div class="well">
    <p><strong><span class="glyphicon glyphicon-pencil"
    aria-hidden="true"></span> Note: The following features are for
    legacy support.</strong></p>

    <dl id="build.source-analysis.legacy">
      <dt><code>DEPENDS ON: x</code> directives in C/Fortran source files</dt>

      <dd>The <code>DEPENDS ON: x</code> directive can be used to identify
      dependencies on other compiled objects. However, it is much better to
      specify this kind of dependency information in the configuration for the
      build where necessary. In any case, in modern Fortran code almost all
      dependencies should be identified automatically via the use of modules
      and/or interface files.</dd>

      <dt><code>calls: x</code> directives in scripts</dt>

      <dd>The <code>calls: x</code> directive can be used to identify a
      dependency on another executable. However, it is much better to specify
      this kind of dependency information in the configuration for the build, and
      leave the source code to concentrate on the run time logic.</dd>

      <dt><samp>*.h</samp> files as Fortran include files</dt>

      <dd><samp>*.h</samp> files are normally identified as C header files.
      However, they are also being used by some old Fortran programs as include
      files. Therefore, when the system analyses a <samp>*.h</samp> file, it has
      to detect the Fortran include syntax, i.e. <samp>include 'file-name'</samp>
      as well as the regular C preprocessor include syntax.</dd>
    </dl>
  </div>

  <div class="well">
    <p><strong><span class="glyphicon glyphicon-pencil"
    aria-hidden="true"></span> Note: Dependency Analysis and Fortran
    OpenMP Sentinels.</strong></p>

    <p>The build system recognises statements with Fortran OpenMP sentinels that
    affect build dependencies. E.g.:</p>

    <pre>
!$ USE my_omp_mod, ONLY: my_omp_sub
! ...
!$ INCLUDE 'my_omp_logic'
</pre>

    <p>These dependencies are normally ignored. However, if a relevant
    <code>build.prop{fc.flag-omp}</code> property is specified, the build system
    will treat these statements as normal dependency statements.</p>
  </div>

  <p>There are some situations when it is not possible for the system to
  identify a dependency. E.g. a Fortran source file may depend on external
  objects that are not detected by the automatic analysis. Therefore, the
  system allows you to specify manual dependencies in the configuration file
  using the <code>build.prop{dep.type}</code> and
  <code>build.prop{ns-dep.type}</code> declarations. E.g.:</p>
  <pre>
# Tell the system that (the object of) food/egg.c depends on chicken.o
build.prop{dep.o}[food/egg.c] = chicken.o

# Tell the system that (the object of) meal/big.c depends on all objects in the
# "food" and "drink" name-spaces
build.prop{ns-dep.o}[meal/big.c] = food drink
</pre>

  <p>Like all declarations that accept name-spaces, if you specify a name-space
  in this declaration, the property will apply to all source files in the
  name-space. If you do not specify a name-space, it applies to the root
  name-space (i.e. globally to all relevant source files).</p>

  <p>The following manual dependency declarations are recognised:</p>

  <dl>
    <dt><a href=
    "annex_cfg.html#make.build.prop.dep.bin">build.prop{dep.bin}</a></dt>

    <dd>Specifies a list of dependencies on a script or a binary
    executable.</dd>

    <dt><a href=
    "annex_cfg.html#make.build.prop.dep.f.module">build.prop{dep.f.module}</a></dt>

    <dd>Specifies a list of Fortran module import dependencies. Note: a
    dependency on a Fortran module called <samp>module_1</samp> becomes an
    <dfn>include</dfn> dependency on <samp>module_1.mod</samp> when the system
    turns the source file into its targets.</dd>

    <dt><a href=
    "annex_cfg.html#make.build.prop.dep.include">build.prop{dep.include}</a></dt>

    <dd>Specifies a list of include file dependencies.</dd>

    <dt><a href=
    "annex_cfg.html#make.build.prop.dep.o">build.prop{dep.o}</a></dt>

    <dd>Specifies a list of link-time object dependencies.</dd>

    <dt><a href=
    "annex_cfg.html#make.build.prop.dep.o.special">build.prop{dep.o.special}</a></dt>

    <dd>Specifies a list of special type of link-time object dependencies.
    Normally, an object file can be put in an object archive before being
    linked with the main object. There are special cases when an object file
    must be specified on the command line of the linker. (E.g. an object file
    containing a Fortran blockdata program unit.) This special behaviour must
    be declared using this declaration.</dd>

    <dt><a href=
    "annex_cfg.html#make.build.prop.ns-dep.o">build.prop{ns-dep.o}</a></dt>

    <dd>Specifies a list of link-time object dependencies on all objects in the
    specified name-space.</dd>
  </dl>

  <p>There are times when you know that your source tree does not contain a
  particular type of dependency, in which case you can switch off the automatic
  analysis by using the <code>build.prop{no-dep.type}</code> declaration. E.g.
  if you know that all include files in the <samp>food</samp> name-space are
  provided outside of the source tree, you can do:</p>
  <pre>
# Do not check for "include" dependencies
build.prop{no-dep.include}[food] = *
</pre>

  <p>All the types supported by the <code>build.prop{dep.type}</code>
  declarations are supported by the <code>build.prop{no-dep.type}</code>,
  except that there is no <code>build.prop{no-dep.o.special}</code>
  (because this type of dependency is never automatic).</p>

  <h3 id="build.target-source">Build Targets from Source Files</h3>

  <p>The system derives the build targets from the source files. E.g. a C
  source file <samp>egg.c</samp> is turned into a compile target to generate
  <samp>egg.o</samp>.</p>

  <p>The following is a list of what targets are available for each type of
  file. The title of each item in the list is in the format <dfn>source type
  -&gt; target key</dfn>. The <dfn>description</dfn> of each target describes
  what the target is, and where appropriate, explains how the target keys are
  named. The <dfn>task</dfn> is the action the target needs to perform to get
  up to date. The <dfn>category and destination</dfn> is the sub-directory and
  destination of the target. The <dfn>properties</dfn> are the list of
  properties that may be used by the <dfn>task</dfn> to update the target. The
  <dfn>dependencies</dfn> list the types of dependencies the target may have.
  The <dfn>update if</dfn> is the condition when the target is considered out
  of date. The <dfn>pass on</dfn> information is a list of dependeny types
  which a target can pass on the status, (see <a href=
  "#build.target-update">Build Targets Update in Incremental Mode</a> for an
  explanation of what this means.)</p>

  <dl>
    <dt>c/cxx -&gt; name</dt>

    <dd>
      <p><dfn>description</dfn>: source file as an include file.</p>

      <p><dfn>task</dfn>: <a href="#build.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.include">include</a> and include/name</p>

      <p><dfn>dependencies</dfn>: include and o (object).</p>

      <p><dfn>update if</dfn>: source file is modified.</p>

      <p><dfn>pass on</dfn>: include, o and o.special.</p>
    </dd>

    <dt>c/cxx -&gt; name.o</dt>

    <dd>
      <p><dfn>description</dfn>: object file. The file is named by mapping the
      base name of the original source file in lower case characters, with the
      file extension replaced by the first value of the <code><a href=
      "annex_cfg.html#make.build.prop.file-ext.o">file-ext.o</a></code>
      property.</p>

      <p><dfn>task</dfn>: <a href="#build.task.compile">compile</a> (cc).</p>

      <p><dfn>category and destination</dfn>: <a href="#build.category.o">o</a>
      and o/name.o</p>

      <p><dfn>properties</dfn>: <a href=
      "annex_cfg.html#make.build.prop.cc">cc</a>, <a href=
      "annex_cfg.html#make.build.prop.cc.flags">cc.flags</a>, <a href=
      "annex_cfg.html#make.build.prop.cc.defs">cc.defs</a>, <a href=
      "annex_cfg.html#make.build.prop.cc.flag-compile">cc.flag-compile</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-define">cc.flag-define</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-include">cc.flag-include</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.include-paths">cc.include-paths</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-omp">cc.flag-omp</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-output">cc.flag-output</a></p>

      <p><dfn>dependencies</dfn>: include and o (object).</p>

      <p><dfn>update if</dfn>: source file or any of the required properties
      are modified, or if any include dependencies are updated.</p>

      <p><dfn>pass on</dfn>: o and o.special.</p>
    </dd>

    <dt>c/cxx (with main function) -&gt; name.exe</dt>

    <dd>
      <p><dfn>description</dfn>: binary executable. The file is named after the
      base name of the original source file, with the file extension replaced by
      the first value of the <code><a href=
      "annex_cfg.html#make.build.prop.file-ext.bin">file-ext.bin</a></code>
      property.</p>

      <p><dfn>task</dfn>: <a href="#build.task.link">link</a> (cc).</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.bin">bin</a> and bin/name.exe</p>

      <p><dfn>properties</dfn>:
      <a href="annex_cfg.html#make.build.prop.ar">ar</a>,
      <a href="annex_cfg.html#make.build.prop.ar.flags">ar.flags</a>,
      <a href="annex_cfg.html#make.build.prop.file-ext.a">file-ext.a</a>,
      <a href="annex_cfg.html#make.build.prop.cc">cc</a>,
      <a href="annex_cfg.html#make.build.prop.cc.flags-ld">cc.flags-ld</a>,
      <a href="annex_cfg.html#make.build.prop.cc.flag-lib">cc.flag-lib</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-lib-path">cc.flag-lib-path</a>,
      <a href="annex_cfg.html#make.build.prop.cc.libs">cc.libs</a>,
      <a href="annex_cfg.html#make.build.prop.cc.lib-paths">cc.lib-paths</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-omp">cc.flag-omp</a>,
      <a href=
      "annex_cfg.html#make.build.prop.cc.flag-output">cc.flag-output</a></p>

      <p><dfn>dependencies</dfn>: name.o and other objects (o and
      o.special).</p>

      <p><dfn>update if</dfn>: source file or any of the required properties
      are modified, or if any dependencies are updated.</p>
    </dd>

    <dt>fortran -&gt; name</dt>

    <dd>
      <p><dfn>description</dfn>: source file as an include file.</p>

      <p><dfn>task</dfn>: <a href="#build.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.include">include</a> and include/name</p>

      <p><dfn>dependencies</dfn>: include and o (object). A source's f.module
      dependency on a module called <samp>xyz</samp> is turned into an include
      dependency on the <samp>xyz.mod</samp>.</p>

      <p><dfn>update if</dfn>: source file is modified.</p>

      <p><dfn>pass on</dfn>: include, o and o.special.</p>
    </dd>

    <dt>fortran (with a valid Fortran program unit) -&gt; unit.o</dt>

    <dd>
      <p><dfn>description</dfn>: object file. The file is named by concatenating
      the lower case characters of the name of the first program unit in the
      source file and the first value of the <code><a href=
      "annex_cfg.html#make.build.prop.file-ext.o">file-ext.o</a></code>
      property.</p>

      <p><dfn>task</dfn>: <a href="#build.task.compile">compile</a> (fc).</p>

      <p><dfn>category and destination</dfn>: <a href="#build.category.o">o</a>
      and o/unit.o</p>

      <p><dfn>properties</dfn>: <a href=
      "annex_cfg.html#make.build.prop.fc">fc</a>, <a href=
      "annex_cfg.html#make.build.prop.fc.flags">fc.flags</a>, <a href=
      "annex_cfg.html#make.build.prop.fc.defs">fc.defs</a>, <a href=
      "annex_cfg.html#make.build.prop.fc.flag-compile">fc.flag-compile</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-define">fc.flag-define</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-include">fc.flag-include</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.include-paths">fc.include-paths</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-module">fc.flag-module</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-omp">fc.flag-omp</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-output">fc.flag-output</a></p>

      <p><dfn>dependencies</dfn>: include and o (object). A source's f.module
      dependency on a module called <samp>xyz</samp> is turned into an include
      dependency on the <samp>xyz.mod</samp>.</p>

      <p><dfn>update if</dfn>: source file or any of the required properties
      are modified, or if any include dependencies are updated.</p>

      <p><dfn>pass on</dfn>: o and o.special.</p>

      <p><dfn>remark</dfn>: trigger <samp>unit.mod</samp> targets if source
      file contains a Fortran module.</p>
    </dd>

    <dt>fortran (with function or subroutine) -&gt; name.interface</dt>

    <dd>
      <p><dfn>description</dfn>: Fortran interface file. The file is named by
      concatenating the base name of the source file with the file extension
      replaced by the <code><a href=
      "annex_cfg.html#make.build.prop.file-ext.f90-interface">file-ext.f90-interface</a></code>
      property.</p>

      <p><dfn>task</dfn>: <a href="#build.task.ext-iface">ext-iface</a></p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.include">include</a> and include/name.interface</p>

      <p><dfn>dependencies</dfn>: unit.o</p>

      <p><dfn>update if</dfn>: source file or unit.o is modified.</p>

      <p><dfn>pass on</dfn>: include, o and o.special.</p>
    </dd>

    <dt>fortran (each module in source) -&gt; unit.mod</dt>

    <dd>
      <p><dfn>description</dfn>: Fortran module definition file. The file is
      named by concatenating the lower case characters of the name of the
      module and the first value of the <code><a href=
      "annex_cfg.html#make.build.prop.file-ext.f90-mod">file-ext.f90-mod</a></code>
      property.</p>

      <p><dfn>task</dfn>: <a href="#build.task.compile-plus">compile+</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.include">include</a> and include/unit.mod</p>

      <p><dfn>dependencies</dfn>: unit.o</p>

      <p><dfn>update if</dfn>: source file or unit.o is modified.</p>

      <p><dfn>pass on</dfn>: o.</p>
    </dd>

    <dt>fortran (with program) -&gt; name.exe</dt>

    <dd>
      <p><dfn>description</dfn>: binary executable. The object file is named
      after the base name of the original source file, with the file extension
      replaced by the first value of the <code><a href=
      "annex_cfg.html#make.build.prop.file-ext.bin">file-ext.bin</a></code>
      property.</p>

      <p><dfn>task</dfn>: <a href="#build.task.link">link</a> (fc).</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.bin">bin</a> and bin/name.exe</p>

      <p><dfn>properties</dfn>:
      <a href="annex_cfg.html#make.build.prop.ar">ar</a>,
      <a href="annex_cfg.html#make.build.prop.ar.flags">ar.flags</a>,
      <a href="annex_cfg.html#make.build.prop.fc">fc</a>,
      <a href="annex_cfg.html#make.build.prop.fc.flags-ld">fc.flags-ld</a>,
      <a href="annex_cfg.html#make.build.prop.fc.flag-lib">fc.flag-lib</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-lib-path">fc.flag-lib-path</a>,
      <a href="annex_cfg.html#make.build.prop.fc.libs">fc.libs</a>,
      <a href="annex_cfg.html#make.build.prop.fc.lib-paths">fc.lib-paths</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-omp">fc.flag-omp</a>,
      <a href=
      "annex_cfg.html#make.build.prop.fc.flag-output">fc.flag-output</a></p>

      <p><dfn>dependencies</dfn>: unit.o and other objects (o and
      o.special).</p>

      <p><dfn>update if</dfn>: source file or any of the required properties
      are modified, or if any dependencies are updated.</p>
    </dd>

    <dt>h -&gt; name</dt>

    <dd>
      <p><dfn>description</dfn>: a header (include) file.</p>

      <p><dfn>task</dfn>: <a href="#build.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.include">include</a> and include/name</p>

      <p><dfn>dependencies</dfn>: include and o (object).</p>

      <p><dfn>update if</dfn>: source file is modified.</p>

      <p><dfn>pass on</dfn>: include, o and o.special.</p>
    </dd>

    <dt>script -&gt; name</dt>

    <dd>
      <p><dfn>description</dfn>: an executable script.</p>

      <p><dfn>task</dfn>: <a href="#build.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.bin">bin</a> and bin/name</p>

      <p><dfn>dependencies</dfn>: bin (executable).</p>

      <p><dfn>update if</dfn>: source file is modified.</p>

      <p><dfn>pass on</dfn>: bin.</p>
    </dd>

    <dt>data -&gt; name-space</dt>

    <dd>
      <p><dfn>description</dfn>: a data file.</p>

      <p><dfn>task</dfn>: <a href="#build.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.etc">etc</a> and etc/name-space</p>

      <p><dfn>update if</dfn>: source file is modified.</p>
    </dd>
  </dl>

  <p>Here is an explanation of what each build system <dfn>task</dfn> does:</p>

  <dl>
    <dt id="build.task.archive">archive</dt>

    <dd>Creates an object archive by invoking an archiver command. (See
    <a href="#build.target-ns">Build Targets from Name-space</a>.)</dd>

    <dt id="build.task.compile">compile</dt>

    <dd>Creates an object file by invoking the C/C++/Fortran compiler on the
    source file.</dd>

    <dt id="build.task.compile-plus">compile+</dt>

    <dd>Copies the Fortran module definition file created by a compile task to
    the include sub-directory.</dd>

    <dt id="build.task.ext-iface">ext-iface</dt>

    <dd>Extracts the calling interfaces of all functions and subroutines in a
    Fortran source file (free format only) and writes the results in an
    interface block that can be included by other Fortran source files with an
    <samp>INCLUDE 'name.interface'</samp> statement. In an incremental build,
    if you have modified a Fortran source file, its interface file will only be
    re-generated if the content of the interface has changed. This can make
    incremental build very efficient, as non-interface changes in a function or
    subroutine will only trigger a re-link of the executable.</dd>

    <dt id="build.task.install">install</dt>

    <dd>Copies the source file to the destination.</dd>

    <dt id="build.task.link">link</dt>

    <dd>Creates an executable by invoking the archiver to load all required
    objects into an archive, and then the C/C++/Fortran compiler on the object
    file previously compiled using a source file containing a main program, with
    the temporary archive.</dd>
  </dl>

  <h3 id="build.target-prop">Build Targets and Properties</h3>

  <p>If you need to specify a property for a specific target, you can either use
  their source file namespace or the target key. E.g. If the
  <samp>sausage.o</samp> target is generated from the source file in the
  <samp>src/food/sausage.f90</samp> namespace, you can specify its Fortran
  compiler flags <code><a href=
  "annex_cfg.html#make.build.prop.fc.flags">build.prop{fc.flags}</a></code> by
  doing either:</p>

  <pre>
build.prop{fc.flags}[sausage.o] = -O4
# would be the same as:
build.prop{fc.flags}[src/food/sausage.f90] = -O4
</pre>

  <p>This works with most property modifiers, even for dependency related
  modifiers such as <code>no-dep.o</code>. E.g.:</p>

  <pre>
build.prop{no-dep.include}[sausage.o] = enum.f90
build.prop{include-paths}[sausage.o] = /path/to/additives
</pre>
  
  <p>However, the following will not work:</p>

  <pre>
build.prop{no-dep.f.module}[sausage.o] = pork
</pre>

  <p>This is because an object file target is never dependent on a Fortran
  module by its name. The following will work, however:</p>

  <pre>
build.prop{no-dep.include}[sausage.o] = pork.mod
build.prop{no-dep.o}[sausage.mod] = pork.o
# would be the same as:
build.prop{no-dep.f.module}[src/food/sausage.f90] = pork
</pre>

  <h3 id="build.target-source-fortran">Build Targets from Source Files: Fortran
  Specifics</h3>

  <p>To ensure that a Fortran application is built automatically, its source
  code should be designed with the following considerations:</p>

  <p><dfn>The name of each compilable program unit should be unique</dfn> in
  the source tree, bearing in mind that Fortran is NOT case sensitive.</p>

  <p><dfn>Always supply an interface for functions and subroutines</dfn>,
  i.e.:</p>

  <ul>
    <li>Place functions and subroutines in a module, and give them the
    <code>PUBLIC</code> attribute. Import them with the <code>USE
    &lt;module&gt;</code> statement. We recommend adding the <code>ONLY</code>
    clause in a <code>USE &lt;module&gt;</code> when importing symbols from a
    module. This makes it easier to locate the source of each symbol, and avoids
    unintentional access to other <code>PUBLIC</code> symbols within the
    <code>MODULE</code>. If you are importing from an intrinsic module, you
    should add the <code>INTRINSIC</code> clause to the <code>USE
    &lt;module&gt;</code> statement to tell the build system not to look for the
    module from your source tree.</li>

    <li>Place functions and subroutines in the <code>CONTAINS</code> section of
    a standalone program unit. There are two advantages for this approach.
    Firstly, the sub-programs will get an automatic interface when the container
    program unit is compiled. Secondly, it should be easier for the compiler to
    provide optimisation when the sub-programs are internal to the caller. The
    disadvantage of this approach is that the sub-programs are local to the
    caller, and so they cannot be called by other program units. Therefore, this
    approach is only suitable for small sub-programs local to a particular
    program unit.</li>

    <li>Use the build system's automatic interface file feature. See below.</li>
  </ul>

  <p>For each free format Fortran source file, e.g. <samp>name.f90</samp>, with
  1 or more top level function and/or subroutine, the system creates a target
  with the <a href="#build.task.ext-iface">ext-iface</a> task in the
  <a href="#build.category.include">include</a> category, e.g.
  <samp>name.interface</samp>, to extract the calling interfaces of all
  functions and subroutines into an interface block. Another Fortran source
  file, e.g. <samp>caller.f90</samp> that relies on the functions and/or
  subroutines in <samp>name.f90</samp> can have an <samp>INCLUDE
  'name.interface'</samp> statement in its specification section, which serves
  2 purposes:</p>

  <ul>
    <li>It allows <samp>caller.f90</samp> to call the functions and/or
    subroutines in <samp>name.f90</samp> with explicit interfaces.</li>

    <li>It introduces an <a href=
    "annex_cfg.html#make.build.prop.dep.include">include</a> dependency for
    <samp>caller.o</samp> on <samp>name.interface</samp>.</li>
  </ul>

  <p>In an incremental build, if you modify <samp>name.f90</samp>, the system
  will only regenerate <samp>name.interface</samp> if only the calling
  interfaces of the functions and/or subroutines in <samp>name.f90</samp> have
  changed. Consequently, non-interface changes in <samp>name.f90</samp> will
  not trigger the re-compile of <samp>caller.o</samp>, but will only trigger a
  re-link of the executable.</p>

  <h3 id="build.target-selection">Build Targets Selection and Rename</h3>

  <p>You need to tell the build system what targets to build or it will do
  nothing. The <code><a href=
  "annex_cfg.html#make.build.target">build.target</a></code> declaration allows
  you to select targets according to their categories, source name-spaces,
  tasks and keys. The logic is demonstrated by the following example:</p>
  <pre>
# Select targets matching these keys
build.target = egg.bin ham.o bacon.sh

# Select all targets doing tasks "install" or "link"
build.target{task} = install link

# Select targets in name-space "foo" or "bar" doing tasks "link"
build.target{task}[foo bar] = link

# Select all targets in the "bin" category
build.target{category} = bin

# Select targets in name-space "foo" in the "etc" category
build.target{category}[foo] = etc
</pre>

  <p>There are times when an automatic target name is not what you want. In
  which case, you can rename a target using the <code><a href=
  "annex_cfg.html#make.build.target-rename">build.target-rename</a></code>
  declaration to specify an alternate name. E.g. if the target
  <samp>bacon.sh</samp> should be called <samp>streaky</samp>, you can do:</p>
  <pre>
build.target-rename = bacon.sh:streaky
</pre>

  <p>In order for a target to build, all its dependencies must be satisfied. If
  a target has a dependency that is not available in the list of targets, the
  build will fail. Normally, you can avoid this by using one of the
  <code>build.prop{no-dep.*}</code> declarations to switch off a non-existent
  dependency, as described in the <a href="#build.source-analysis">Build Source
  Analysis</a> section. However, there may be times when this is inefficient or
  insufficient, in which case you can use the property <code><a href=
  "annex_cfg.html#make.build.prop.ignore-missing-dep-ns">ignore-missing-dep-ns</a></code>
  to specify a list of source name-spaces, in which targets can ignore missing
  dependencies. E.g.:</p>
  <pre>
# Allows targets in the "foo" and "bar/baz"
# name-spaces to ignore missing dependencies.
build.prop{ignore-missing-dep-ns} = foo bar/baz
</pre>

  <h3 id="build.target-file-ext">Build Targets File Extensions</h3>

  <p>You can rename the file name extension of the targets using
  <code>build.prop{file-ext.type}</code> declaration (provided that the file
  name extension is supported by your compiler, etc). E.g. if you want your
  binary executables to have <samp>.bin</samp> extension rather than the
  default <samp>.exe</samp>, you can do:</p>
  <pre>
build.prop{file-ext.bin} = .bin
</pre>

  <p>The following file extensions are currently used by the system:</p>

  <dl>
    <dt><a href="annex_cfg.html#make.build.prop.file-ext.a">a</a> (object
    archive)</dt>

    <dd>.a</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.bin">bin</a> (binary
    executable)</dt>

    <dd>.exe</dd>

    <dt><a href=
    "annex_cfg.html#make.build.prop.file-ext.f90-interface">f90-interface</a>
    (Fortran free format interface file)</dt>

    <dd>.interface</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.f90-mod">f90-mod</a>
    (Fortran compiler module definition file)</dt>

    <dd>.mod</dd>

    <dt><a href="annex_cfg.html#make.build.prop.file-ext.o">o</a> (object
    file)</dt>

    <dd>.o</dd>
  </dl>

  <h3 id="build.target-ns">Build Targets from Name-space</h3>

  <p>Apart from source file targets, the build system also generates targets
  for each (directory-level) name-space. One target is for creating an object
  archive to contain all object files in the name-space. The other target is a
  convenient shorthand to allow all data files in the name-space to be
  installed. The following is the full description:</p>

  <dl>
    <dt>name-space &gt; name-space/libo.a</dt>

    <dd>
      <p><dfn>description</dfn>: object archive.</p>

      <p><dfn>task</dfn>: <a href="#build.task.archive">archive</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.lib">lib</a> and lib/name-space/libo.a</p>

      <p><dfn>dependencies</dfn>: all o (object) targets in the name-space.</p>

      <p><dfn>properties</dfn>: <a href=
      "annex_cfg.html#make.build.prop.ar">ar</a>, <a href=
      "annex_cfg.html#make.build.prop.ar.flags">ar.flags</a></p>

      <p><dfn>update if</dfn>: any dependencies or properties are modified.</p>
    </dd>

    <dt>name-space &gt; name-space/.etc</dt>

    <dd>
      <p><dfn>description</dfn>: dummy file.</p>

      <p><dfn>task</dfn>: <a href="#build.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#build.category.etc">etc</a> and etc/name-space/.etc</p>

      <p><dfn>dependencies</dfn>: all data files in the name-space.</p>

      <p><dfn>update if</dfn>: any dependencies are modified.</p>
    </dd>
  </dl>

  <h3 id="build.target-update">Build Targets Update in Incremental Mode</h3>

  <p>In incremental mode, a target is only updated if it is marked out of date.
  A target is considered out of date if:</p>

  <ul>
    <li>the source file's checksum is changed.</li>

    <li>a required property is modified.</li>

    <li>a dependency is marked as modified, and the dependency is a type that
    the target cannot pass on. E.g. If <samp>object_1.o</samp> depends on
    <samp>object_2.o</samp>, and <samp>object_2.o</samp> is marked as modified,
    the system does not need to re-compile <samp>object_1.o</samp> (as long as
    its source file and properties remain unchanged). However,
    <samp>object_1.o</samp> will have to pass the information up the dependency
    tree, so that a target with a <samp><a href=
    "#build.task.link">link</a></samp> task to build an executable (or an
    <samp><a href="#build.task.archive">archive</a></samp> task to build a
    library) will know that it needs to be updated.</li>

    <li>a dependency is passing on a <q>modified</q> status for a dependency
    type, which cannot be passed on by the target.</li>

    <li>the target does not exist or its checksum is changed.</li>
  </ul>

  <p>If, after an update, the target's checksum is the same as before, the
  target will be considered unchanged and up to date. In an incremental build,
  the use of checksum ensures that any targets manually modified by the user
  after the previous build is rebuilt accordingly. It also prevents unnecessary
  updates of targets in incremental and inherited builds.</p>

  <p>E.g. Consider an incremental build where the only change is the content of
  a Fortran module <samp>my_mod.f90</samp>. The content change should trigger
  an update of the <samp>my_mod.o</samp> and <samp>my_mod.mod</samp> targets,
  and everything depending on them. However, if the source content is modified
  in such a way that it does not affect the module's public interface, most
  compilers will generate an identical <samp>my_mod.mod</samp>. The system can
  detect this by comparing the checksums. If <samp>my_mod.mod</samp> is
  unchanged, the build system will not need to trigger the re-compile of all
  targets depending on <samp>my_mod.mod</samp>, and it will only need to
  re-link the executable. This allows incremental builds to be more
  efficient.</p>

  <div class="well">
    <p><strong><span class="glyphicon glyphicon-pencil"
    aria-hidden="true"></span> Note - checksum algorithm</strong></p>

    <p>By default, the MD5 algorithm is used to calculate the checksum. This is
    normally good enough to detect whether a file is modified or not. If this is
    insufficient for whatever reasons, you can tell the build system to use one
    of the SHA algorithms supported by the Perl module <a href=
    "http://perldoc.perl.org/Digest/SHA.html">Digest::SHA</a>, by setting the
    value of <a href=
    "annex_cfg.html#make.build.prop.checksum-method">build.prop{checksum-method}</a>.</p>
  </div>

  <h3 id="build.inherit">Build Inheritance</h3>

  <p>If a previous build with a similar configuration exists in another
  location, it can be more efficient to inherit from this previous build in
  your current build. This works like a normal incremental build, except that
  your build will only contain the changes you have specified (compared with
  the inherited build) instead of the full set of targets.</p>

  <p>The current build inherits all properties and target settings, as well as
  sources and targets from the inherited build. While properties and target
  settings can be overridden with a corresponding declaration, source
  inheritance can only be prevented by using a <code><a href=
  "annex_cfg.html#make.build.prop.no-inherit-source">build.prop{no-inherit-source}</a></code>
  declaration. E.g.:</p>
  <pre>
# Prevents inheritance from some name-spaces:
build.prop{no-inherit-source} = food/mint drink/soft/cola.c
</pre>

  <p>For multiple inheritance, the last one takes precedence, and any search
  for source files or targets are recursive and depth first. For instance, if
  we have the following declarations in the current FCM make configuration:</p>
  <pre>
use = /path/to/a /path/to/b /path/to/c
</pre>

  <p>and the following in the FCM make configuration of
  <samp>/path/to/b</samp>:</p>
  <pre>
use /path/to/d
</pre>

  <p>The relationship looks like:</p>
  <pre>
/path/to/current
    /path/to/c
    /path/to/b
        /path/to/d
    /path/to/a
</pre>

  <p>Therefore, we would expect the search path to follow the order:</p>
  <pre>
/path/to/current
/path/to/c
/path/to/b
/path/to/d
/path/to/a
</pre>

  <p>In its normal setting, the system does not inherit targets in the
  <samp>bin</samp>, <samp>etc</samp> and <samp>lib</samp> categories. A target
  in one of these categories is rebuilt in the current destination, whether the
  inherited target is up to date or not. This allows someone to use the
  executables of the build by setting the <var>PATH</var> environment variable
  to point only to <samp>$DEST/build/bin/</samp> (where <var>$DEST</var> is the
  destination of the current make). If this behaviour is undesirable for
  whatever reason, it can be altered using the <code><a href=
  "annex_cfg.html#make.build.prop.no-inherit-target-category">build.prop{no-inherit-target-category}</a></code>
  declaration.</p>

  <dl>
    <dt>Build inheritance limitation: handling of include files</dt>

    <dd>
      <p>The build system uses the compiler's <code>-I</code> option to specify
      the search path for include files. E.g. it uses this option to specify
      the <samp>inc/</samp> sub-directories of the current build and its
      inherited build.</p>

      <p>However, some compilers (e.g. <code>cpp</code>) search for include
      files from the container directory of the source file before searching
      for the paths specified by the <code>-I</code> options. This behaviour
      may cause the build to behave incorrectly.</p>

      <p>Consider a source file <samp>egg/hen.c</samp> that includes
      <samp>fried.h</samp>. If the directory structure looks like:</p>
      <pre>
# Sources in inherited build:
egg/hen.c
egg/fried.h

# Sources in current build:
egg/fried.h
</pre>

      <p>The system will correctly identify that <samp>fried.h</samp> is out of
      date, and trigger a re-compilation of <samp>egg/hen.c</samp>. However, if
      the compiler searches for the include files from the container directory
      of the source file first, it will wrongly use the include file in the
      inherited build instead of the current one.</p>

      <p>If your directory structure does not have any include files in the same
      directory as the source files that include them then you do not need to
      worry. If it does then you need to check whether you are affected by this
      problem before using an inherited build. The situation will vary
      according to whether the affected code uses Fortran or preprocessor
      include statements and also whether you are using the
      <a href="#preprocess">preprocess system</a>. Some compilers (e.g.
      <code>gfortran</code>) work fine for Fortran includes but not preprocessor
      includes. Others (e.g. <code>ifort</code>) have options which can be used
      (e.g. <code>-assume nosource_include</code>) to get the desired behaviour.
      The FCM distribution includes some simple test code to help you test how
      your chosen compilers behave. If you cannot ensure the correct behaviour
      then it is safer not to use inherited builds.</p>
    </dd>
  </dl>

  <h3 id="build.diagnostic">Build Diagnostic</h3>

  <p>The amount of diagnostic messages generated by the build system is
  dependent on the diagnostic verbosity level that can be modified by the
  <code>-v</code> and <code>-q</code> options to the <code>fcm make</code>
  command.</p>

  <p>The following is a list of diagnostic output at each verbosity level:</p>

  <dl>
    <dt>-q</dt>

    <dd>
      <ul>
        <li>Exceptions.</li>
      </ul>
    </dd>

    <dt>default</dt>

    <dd>
      <ul>
        <li>Everything at the -q level.</li>

        <li>Start time of the build.</li>

        <li>The summary of source analysis.</li>

        <li>The summary of targets. Each row except the last reports the number
        of modified and unchanged targets with a given type of task, and the
        total time spent to perform the tasks. The last row reports the total
        number of modified and unchanged targets, and the actual elapsed time.
        It is worth noting that the elapsed time in a multi-process build
        should be significant shorter than the sum of the total time for each
        type of task. E.g.:
          <pre>
[info] compile   targets: modified=5, unchanged=0, total-time=0.5s
[info] compile+  targets: modified=1, unchanged=0, total-time=0.0s
[info] ext-iface targets: modified=2, unchanged=0, total-time=0.0s
[info] install   targets: modified=1, unchanged=0, total-time=0.0s
[info] link      targets: modified=1, unchanged=0, total-time=0.1s
[info] TOTAL     targets: modified=10, unchanged=0, elapsed-time=0.7s
</pre>
        </li>

        <li>Total time.</li>
      </ul>
    </dd>

    <dt>-v</dt>

    <dd>
      <ul>
        <li>Everything at the default level.</li>

        <li>Elapsed time and name-space for each analysed source.</li>

        <li>Task name, elapsed time, target status (<samp>M</samp> for modified
        or <samp>U</samp> for unchanged), target key, and source name-space for
        each modified target. E.g.:
          <pre>
[info] compile    0.0 M hello_func.o         &lt;- lib/function/hello_func.f90
[info] ext-iface  0.0 M hello_func.interface &lt;- lib/function/hello_func.f90
[info] install    0.0 M hello_inc.f90        &lt;- include/hello_inc.f90
[info] compile    0.0 M hello_1.o            &lt;- bin/hello_1.f90
[info] link       0.1 M hello_1.exe          &lt;- bin/hello_1.f90
</pre>
        </li>
      </ul>
    </dd>

    <dt>-vv</dt>

    <dd>
      <ul>
        <li>Everything at the -v level.</li>

        <li>A list of dependencies (type and name) of each analysed source.
        E.g.
          <pre>
[info] analyse  0.0 bin/hello_1.f90
[info]              -&gt; (  include) hello_inc.f90
[info]              -&gt; (        o) hello_void.o
[info]              -&gt; ( f.module) hello_mod
</pre>
        </li>

        <li>A list of the available targets from the sources. Each row contains
        the source namespace, the target task, the target category and the key
        of the target. E.g.:
          <pre>
[info] source-&gt;target / -&gt; (archive) lib/ libo.a
[info] source-&gt;target hello.f90 -&gt; (link) bin/ hello.exe
[info] source-&gt;target hello.f90 -&gt; (install) include/ hello.f90
[info] source-&gt;target hello.f90 -&gt; (compile) o/ hello.o
[info] source-&gt;target world.f90 -&gt; (install) include/ world.f90
[info] source-&gt;target world.f90 -&gt; (compile+) include/ world.mod
[info] source-&gt;target world.f90 -&gt; (compile) o/ world.o
</pre>
        </li>

        <li>A list of the required targets for this build. Each row contains
        the task, the category and the key of the target. E.g.:
          <pre>
[info] required-target: link      bin     hello_1.exe
</pre>
        </li>

        <li>The dependency tree of all the required targets. (N.B. A
        <samp>(n-deps=N)</samp> at the end of a line means that the target has
        already appeared earlier and that it has <samp>N</samp> direct
        dependencies, which will not be reported again.) E.g.:
          <pre>
[info] target hello_1.exe
[info] target  - hello_void.o
[info] target  - hello_1.o
[info] target  -  - hello_mod.mod
[info] target  -  -  - hello_mod.o
[info] target  -  - hello_void.o
[info] target  -  - hello_inc.f90
[info] target  -  -  - hello_sub.interface
[info] target  -  -  -  - hello_sub.o
[info] target  -  -  -  -  - hello_func.interface
[info] target  -  -  -  -  -  - hello_func.o
[info] target  - hello_2.o
[info] target  -  - hello_mod.mod (n-deps=1)
</pre>
        </li>

        <li>Each shell command invoked with elapsed time and return code.</li>

        <li>STDOUT and STDERR from shell commands invoked by the build
        tasks, e.g. diagnostic output from compilers and linkers.</li>
      </ul>
    </dd>
  </dl>

  <h2 id="preprocess">Preprocess</h2>

  <p>As most modern compilers can handle preprocessing, you should normally
  leave preprocessing to the compiler. However, it is recognised that some code
  is written with preprocessor directives that can alter the calling interface
  of the procedure and/or their dependencies. If a source file requires
  preprocessing in such a way, we have to preprocess it before feeding it to
  the build system. The preprocess system can be used to do this. It is
  typically run as a step before build.</p>

  <p>However, using a separate preprocess step is not the best way of working,
  as it adds an overhead to the build process. If your code requires
  preprocessing, you should try to design it to avoid changes in the above.</p>

  <p>In practice, the only reasonable use of a preprocessor with Fortran is for
  code selection. For example, preprocessing is useful for isolating machine
  specific libraries or instructions, where it may be appropriate to use inline
  alternatives for small sections of code. Another example is when multiple
  versions of the same procedure exist in the source tree and you need to use
  the preprocessor to select the correct version for your build.</p>

  <p>Avoid using the a preprocessor for code inclusion, as you should be able
  to do the same via the Fortran <code>INCLUDE</code> statement. You should
  also avoid embedding preprocessor macros within the continuations of a
  Fortran statement, as it can make your code very confusing.</p>

  <p>The preprocess system works using the same logic as the build system, but
  is configured primarily to preprocess C/C++ and Fortran source files. We
  shall document only the main differences to the build system in the remainder
  of this section.</p>

  <h3 id="preprocess.basic">Preprocess: Basic</h3>

  <p>A typical usage of the preprocess system may look like:</p>
  <pre>
steps = extract preprocess build

# ... some extract configuration

# Switch off preprocessing for all
preprocess.target{task} =
# Only preprocess source files in these name-spaces
preprocess.target{task}[foo/bar egg/fried.F90] = process
# Specifies the macro definitions for the Fortran preprocessor
preprocess.prop{fpp.defs} = THING=stuff HIGH=tall
# Specifies the macro definitions for the C preprocessor
preprocess.prop{cpp.defs} = LOWER=lower UNDER LINUX

# ... some build configuration
</pre>

  <p>The result of the preprocess can be found in the sub-directories of the
  <samp>preprocess/</samp> sub-directory. There are only 2 target
  categories:</p>

  <dl>
    <dt id="preprocess.category.include"><samp>include</samp></dt>

    <dd>e.g. include files.</dd>

    <dt id="preprocess.category.src"><samp>src</samp></dt>

    <dd>e.g. preprocessed source files</dd>
  </dl>

  <h3 id="preprocess.source-type">Preprocess Source Types</h3>

  <p>Only files in the following types (with the given file extensions) are
  recognised by the preprocess system:</p>

  <dl>
    <dt><a href="annex_cfg.html#make.preprocess.prop.file-ext.cpp">cpp</a>
    (C/C++ source file)</dt>

    <dd>.c .m .cc .cp .cxx .cpp .CPP .c++ .C .mm .M</dd>

    <dt><a href="annex_cfg.html#make.preprocess.prop.file-ext.fpp">fpp</a>
    (Fortran source file requiring preprocessing)</dt>

    <dd>.F .FOR .FTN .F90 .F95</dd>

    <dt><a href="annex_cfg.html#make.preprocess.prop.file-ext.h">h</a>
    (Preprocessor header file)</dt>

    <dd>.h</dd>
  </dl>

  <h3 id="preprocess.source-analysis">Preprocess Source Analysis</h3>

  <p>The preprocess system only looks for include dependencies using the
  pattern <samp>#include "name.h"</samp>. Macros using the angle brackets
  syntax (e.g. <samp>#include &lt;name.h&gt;</samp>) are ignored.</p>

  <h3 id="preprocess.target-source">Preprocess Targets from Source Files</h3>

  <p>The preprocess system only generates targets from source files, (i.e.
  targets are not generated by name-spaces). Targets of the preprocess system
  perform one of the following <dfn>tasks</dfn>:</p>

  <dl>
    <dt id="preprocess.task.install">install</dt>

    <dd>Copies the source file to the destination.</dd>

    <dt id="preprocess.task.process">process</dt>

    <dd>Creates a new source file by invoking the C/Fortran preprocessor on the
    original source file.</dd>
  </dl>

  <p>By default, it attempts to build all targets with a <samp><a href=
  "#preprocess.task.process">process</a></samp> task, i.e.:</p>
  <pre>
preprocess.target =
preprocess.target{task} = process
preprocess.target{category} =
</pre>

  <p>Here is a list of what targets are available for each type of file:</p>

  <dl>
    <dt>cpp -&gt; name-space</dt>

    <dd>
      <p><dfn>description</dfn>: the preprocessed version of the original
      file.</p>

      <p><dfn>task</dfn>: <a href="#preprocess.task.process">process</a>
      (cpp).</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#preprocess.category.src">src</a> and src/name-space</p>

      <p><dfn>properties</dfn>: <a href=
      "annex_cfg.html#make.preprocess.prop.cpp">cpp</a>, <a href=
      "annex_cfg.html#make.preprocess.prop.cpp.flags">cpp.flags</a>, <a href=
      "annex_cfg.html#make.preprocess.prop.cpp.defs">cpp.defs</a>, <a href=
      "annex_cfg.html#make.preprocess.prop.cpp.flag-define">cpp.flag-define</a>,
      <a href=
      "annex_cfg.html#make.preprocess.prop.cpp.flag-include">cpp.flag-include</a>,
      <a href=
      "annex_cfg.html#make.preprocess.prop.cpp.include-paths">cpp.include-paths</a></p>
      <p><dfn>dependencies</dfn>: include.</p>

      <p><dfn>update if</dfn>: source file or any of the required properties
      are modified, or if any include dependencies are updated.</p>
    </dd>

    <dt>fpp -&gt; name-space</dt>

    <dd>
      <p><dfn>description</dfn>: the preprocessed version of the original
      file.</p>

      <p><dfn>task</dfn>: <a href="#preprocess.task.process">process</a>
      (fpp).</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#preprocess.category.src">src</a> and src/name-space</p>

      <p><dfn>properties</dfn>: <a href=
      "annex_cfg.html#make.preprocess.prop.fpp">fpp</a>, <a href=
      "annex_cfg.html#make.preprocess.prop.fpp.flags">fpp.flags</a>, <a href=
      "annex_cfg.html#make.preprocess.prop.fpp.defs">fpp.defs</a>, <a href=
      "annex_cfg.html#make.preprocess.prop.fpp.flag-define">fpp.flag-define</a>,
      <a href=
      "annex_cfg.html#make.preprocess.prop.fpp.flag-include">fpp.flag-include</a>,
      <a href=
      "annex_cfg.html#make.preprocess.prop.fpp.include-paths">fpp.include-paths</a></p>

      <p><dfn>dependencies</dfn>: include.</p>

      <p><dfn>update if</dfn>: source file or any of the required properties
      are modified, or if any include dependencies are updated.</p>
    </dd>

    <dt>h -&gt; name</dt>

    <dd>
      <p><dfn>description</dfn>: a header (include) file.</p>

      <p><dfn>task</dfn>: <a href="#preprocess.task.install">install</a>.</p>

      <p><dfn>category and destination</dfn>: <a href=
      "#preprocess.category.include">include</a> and include/name</p>

      <p><dfn>dependencies</dfn>: include.</p>

      <p><dfn>update if</dfn>: source file is modified.</p>
    </dd>
  </dl>

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