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cmake-developer (7)

Name

cmake-developer - CMake Developer Reference

Synopsis

Please see following description for synopsis

Description

CMAKE-DEVELOPER(7)                   CMake                  CMAKE-DEVELOPER(7)



NAME
       cmake-developer - CMake Developer Reference

INTRODUCTION
       This manual is intended for reference by developers modifying the CMake
       source tree itself.

PERMITTED C++ SUBSET
       CMake is required to build with  ancient  C++  compilers  and  standard
       library implementations.  Some common C++ constructs may not be used in
       CMake in order to build with such toolchains.

   std::auto_ptr
       Some implementations have a std::auto_ptr which can not be  used  as  a
       return  value  from  a  function.  std::auto_ptr  may  not be used. Use
       cmsys::auto_ptr instead.

   size_t
       Various implementations have differing implementation of size_t.   When
       assigning  the result of .size() on a container for example, the result
       should be assigned to size_t not to std::size_t, unsigned int or  simi-
       lar types.

ADDING COMPILE FEATURES
       CMake  reports an error if a compiler whose features are known does not
       report support for a particular requested feature.  A compiler is  con-
       sidered  to  have known features if it reports support for at least one
       feature.

       When adding a new compile feature to CMake, it is  therefore  necessary
       to  list support for the feature for all CompilerIds which already have
       one or more feature supported, if the new feature is available for  any
       version of the compiler.

       When  adding the first supported feature to a particular CompilerId, it
       is necessary to list support for  all  features  known  to  cmake  (See
       CMAKE_C_COMPILE_FEATURES  and  CMAKE_CXX_COMPILE_FEATURES  as appropri-
       ate),   where   available   for   the   compiler.    Furthermore,   set
       CMAKE_<LANG>_STANDARD_DEFAULT  to  the  default language standard level
       the compiler uses, or to the empty string if the compiler has no notion
       of standard levels (such as MSVC).

       It  is sensible to record the features for the most recent version of a
       particular CompilerId first, and then work backwards.  It  is  sensible
       to  try to create a continuous range of versions of feature releases of
       the compiler.  Gaps in the range indicate incorrect  features  recorded
       for intermediate releases.

       Generally,  features are made available for a particular version if the
       compiler vendor documents availability of the feature  with  that  ver-
       sion.   Note that sometimes partially implemented features appear to be
       functional in previous releases (such  as  cxx_constexpr  in  GNU  4.6,
       though  availability  is documented in GNU 4.7), and sometimes compiler
       vendors document availability of  features,  though  supporting  infra-
       structure  is not available (such as __has_feature(cxx_generic_lambdas)
       indicating non-availability in Clang 3.4, though it  is  documented  as
       available,  and fixed in Clang 3.5).  Similar cases for other compilers
       and versions need to be investigated when extending  CMake  to  support
       them.

       When a vendor releases a new version of a known compiler which supports
       a previously unsupported feature, and there are already known  features
       for  that  compiler, the feature should be listed as supported in CMake
       for that version of the compiler as soon as reasonably possible.

       Standard-specific/compiler-specific  variables  such   CMAKE_CXX98_COM-
       PILE_FEATURES are deliberately not documented.  They only exist for the
       compiler-specific implementation of adding the -std  compile  flag  for
       compilers which need that.

HELP
       The  Help  directory contains CMake help manual source files.  They are
       written using the  reStructuredText  markup  syntax  and  processed  by
       Sphinx to generate the CMake help manuals.

   Markup Constructs
       In addition to using Sphinx to generate the CMake help manuals, we also
       use a C++-implemented document processor to  print  documents  for  the
       --help-*  command-line  help options.  It supports a subset of reStruc-
       turedText markup.  When authoring or modifying documents, please verify
       that  the command-line help looks good in addition to the Sphinx-gener-
       ated html and man pages.

       The command-line  help  processor  supports  the  following  constructs
       defined by reStructuredText, Sphinx, and a CMake extension to Sphinx.

       CMake Domain directives
              Directives  defined in the CMake Domain for defining CMake docu-
              mentation objects are printed in command-line help output as  if
              the lines were normal paragraph text with interpretation.

       CMake Domain interpreted text roles
              Interpreted   text   roles  defined  in  the  CMake  Domain  for
              cross-referencing CMake documentation objects  are  replaced  by
              their  link  text  in command-line help output.  Other roles are
              printed literally and not processed.

       code-block directive
              Add a literal  code  block  without  interpretation.   The  com-
              mand-line  help  processor  prints the block content without the
              leading directive line and with common indentation  replaced  by
              one space.

       include directive
              Include  another  document  source  file.  The command-line help
              processor prints the included document inline with the referenc-
              ing document.

       literal block after ::
              A  paragraph  ending  in  :: followed by a blank line treats the
              following indented block as literal text without interpretation.
              The  command-line  help  processor  prints  the :: literally and
              prints the block content with common indentation replaced by one
              space.

       note directive
              Call  out  a  side note.  The command-line help processor prints
              the block content as if the lines  were  normal  paragraph  text
              with interpretation.

       parsed-literal directive
              Add  a  literal  block  with  markup  interpretation.   The com-
              mand-line help processor prints the block  content  without  the
              leading  directive  line and with common indentation replaced by
              one space.

       productionlist directive
              Render context-free grammar productions.  The command-line  help
              processor  prints  the block content as if the lines were normal
              paragraph text with interpretation.

       replace directive
              Define a |substitution| replacement.  The command-line help pro-
              cessor  requires a substitution replacement to be defined before
              it is referenced.

       |substitution| reference
              Reference a substitution replacement previously defined  by  the
              replace directive.  The command-line help processor performs the
              substitution and replaces all newlines in the  replacement  text
              with spaces.

       toctree directive
              Include other document sources in the Table-of-Contents document
              tree.  The command-line help  processor  prints  the  referenced
              documents inline as part of the referencing document.

       Inline  markup constructs not listed above are printed literally in the
       command-line help output.  We prefer to use  inline  markup  constructs
       that look correct in source form, so avoid use of \-escapes in favor of
       inline literals when possible.

       Explicit markup blocks not matching directives listed above are removed
       from  command-line  help  output.  Do not use them, except for plain ..
       comments that are removed by Sphinx too.

       Note that nested indentation of blocks is not recognized  by  the  com-
       mand-line help processor.  Therefore:

       o Explicit  markup  blocks are recognized only when not indented inside
         other blocks.

       o Literal blocks after paragraphs ending in  ::  but  not  at  the  top
         indentation level may consume all indented lines following them.

       Try to avoid these cases in practice.

   CMake Domain
       CMake  adds  a  Sphinx  Domain  called  cmake,  also  called the "CMake
       Domain".  It defines several "object" types for CMake documentation:

       command
              A CMake language command.

       generator
              A CMake native build system generator.  See  the  cmake(1)  com-
              mand-line tool's -G option.

       manual A CMake manual page, like this cmake-developer(7) manual.

       module A  CMake  module.   See  the  cmake-modules(7)  manual  and  the
              include() command.

       policy A CMake  policy.   See  the  cmake-policies(7)  manual  and  the
              cmake_policy() command.

       prop_cache, prop_dir, prop_gbl, prop_sf, prop_inst, prop_test, prop_tgt
              A  CMake  cache, directory, global, source file, installed file,
              test, or target property, respectively.  See  the  cmake-proper-
              ties(7) manual and the set_property() command.

       variable
              A  CMake  language  variable.  See the cmake-variables(7) manual
              and the set() command.

       Documentation objects in  the  CMake  Domain  come  from  two  sources.
       First,  the  CMake  extension to Sphinx transforms every document named
       with the form Help/<type>/<file-name>.rst to a domain object with  type
       <type>.  The object name is extracted from the document title, which is
       expected to be of the form:

          <object-name>
          -------------

       and to appear at or near the top of the  .rst  file  before  any  other
       lines starting in a letter, digit, or <.  If no such title appears lit-
       erally in the .rst file, the object name  is  the  <file-name>.   If  a
       title  does  appear,  it  is  expected  that  <file-name>  is  equal to
       <object-name> with any < and > characters removed.

       Second, the CMake Domain provides directives to define  objects  inside
       other documents:

          .. command:: <command-name>

           This indented block documents <command-name>.

          .. variable:: <variable-name>

           This indented block documents <variable-name>.

       Object  types for which no directive is available must be defined using
       the first approach above.

   Cross-References
       Sphinx  uses  reStructuredText  interpreted  text  roles   to   provide
       cross-reference  syntax.   The  CMake  Domain  provides for each domain
       object type a role of the  same  name  to  cross-reference  it.   CMake
       Domain roles are inline markup of the forms:

          :type:`name`
          :type:`text <name>`

       where  type  is  the  domain  object type and name is the domain object
       name.  In the first form the link text will be name (or name()  if  the
       type  is  command)  and  in  the  second form the link text will be the
       explicit text.  For example, the code:

          * The :command:`list` command.
          * The :command:`list(APPEND)` sub-command.
          * The :command:`list() command <list>`.
          * The :command:`list(APPEND) sub-command <list>`.
          * The :variable:`CMAKE_VERSION` variable.
          * The :prop_tgt:`OUTPUT_NAME_<CONFIG>` target property.

       produces:

       o The list() command.

       o The list(APPEND) sub-command.

       o The list() command.

       o The list(APPEND) sub-command.

       o The CMAKE_VERSION variable.

       o The OUTPUT_NAME_<CONFIG> target property.

       Note that CMake Domain roles differ from  Sphinx  and  reStructuredText
       convention  in  that  the  form  a<b>,  without a space preceding <, is
       interpreted as a name instead of link text  with  an  explicit  target.
       This  is  necessary  because we use <placeholders> frequently in object
       names like OUTPUT_NAME_<CONFIG>.  The form a <b>, with a space  preced-
       ing <, is still interpreted as a link text with an explicit target.

   Style
   Style: Section Headers
       When  marking  section titles, make the section decoration line as long
       as the title text.  Use only a line below the  title,  not  above.  For
       example:

          Title Text
          ----------

       Capitalize the first letter of each non-minor word in the title.

       The section header underline character hierarchy is

       o #: Manual group (part) in the master document

       o *: Manual (chapter) title

       o =: Section within a manual

       o -: Subsection or CMake Domain object document title

       o ^: Subsubsection or CMake Domain object document section

       o ": Paragraph or CMake Domain object document subsection

   Style: Whitespace
       Use  two  spaces  for indentation.  Use two spaces between sentences in
       prose.

   Style: Line Length
       Prefer to restrict the width of lines to 75-80 columns.  This is not  a
       hard  restriction,  but  writing  new  paragraphs wrapped at 75 columns
       allows space for adding minor content without  significant  re-wrapping
       of content.

   Style: Prose
       Use American English spellings in prose.

   Style: Starting Literal Blocks
       Prefer  to  mark  the start of literal blocks with :: at the end of the
       preceding  paragraph.  In  cases  where  the  following  block  gets  a
       code-block  marker,  put  a  single : at the end of the preceding para-
       graph.

   Style: CMake Command Signatures
       Command signatures should be marked up as plain literal blocks, not  as
       cmake code-blocks.

       Signatures  are  separated  from preceding content by a section header.
       That is, use:

          ... preceding paragraph.

          Normal Libraries
          ^^^^^^^^^^^^^^^^

          ::

            add_library(<lib> ...)

          This signature is used for ...

       Signatures of commands should wrap optional parts with square brackets,
       and  should  mark  list  of  optional arguments with an ellipsis (...).
       Elements of the signature which are specified by  the  user  should  be
       specified  with  angle  brackets, and may be referred to in prose using
       inline-literal syntax.

   Style: Boolean Constants
       Use "OFF" and "ON" for boolean values which  can  be  modified  by  the
       user,   such  as  POSITION_INDEPENDENT_CODE.  Such  properties  may  be
       "enabled" and "disabled". Use "True" and "False"  for  inherent  values
       which  can't be modified after being set, such as the IMPORTED property
       of a build target.

   Style: Inline Literals
       Mark up references to keywords in signatures,  file  names,  and  other
       technical terms with inline-literal syntax, for example:

          If ``WIN32`` is used with :command:`add_executable`, the
          :prop_tgt:`WIN32_EXECUTABLE` target property is enabled. That command
          creates the file ``<name>.exe`` on Windows.

   Style: Cross-References
       Mark  up  linkable references as links, including repeats.  An alterna-
       tive,       which       is       used       by       wikipedia       (-
       http://en.wikipedia.org/wiki/WP:REPEATLINK),  is to link to a reference
       only once per article. That style is not used in CMake documentation.

   Style: Referencing CMake Concepts
       If referring to a concept which corresponds to  a  property,  and  that
       concept is described in a high-level manual, prefer to link to the man-
       ual section instead of the property. For example:

          This command creates an :ref:`Imported Target <Imported Targets>`.

       instead of:

          This command creates an :prop_tgt:`IMPORTED` target.

       The latter should be used only when referring specifically to the prop-
       erty.

       References to manual sections are not automatically created by creating
       a section, but code such as:

          .. _`Imported Targets`:

       creates a suitable anchor.  Use an anchor name which matches  the  name
       of the corresponding section.  Refer to the anchor using a cross-refer-
       ence with specified text.

       Imported Targets need the IMPORTED term marked up with care in particu-
       lar  because the term may refer to a command keyword (IMPORTED), a tar-
       get property (IMPORTED), or a concept (Imported Targets).

       Where a property, command or variable is related conceptually  to  oth-
       ers, by for example, being related to the buildsystem description, gen-
       erator expressions or Qt, each relevant property, command  or  variable
       should  link  to the primary manual, which provides high-level informa-
       tion.  Only particular information relating to the command should be in
       the documentation of the command.

   Style: Referencing CMake Domain Objects
       When  referring  to CMake Domain objects such as properties, variables,
       commands etc, prefer to link to the target object and follow that  with
       the type of object it is.  For example:

          Set the :prop_tgt:`AUTOMOC` target property to ``ON``.

       Instead of

          Set the target property :prop_tgt:`AUTOMOC` to ``ON``.

       The  policy directive is an exception, and the type us usually referred
       to before the link:

          If policy :prop_tgt:`CMP0022` is set to ``NEW`` the behavior is ...

       However, markup self-references with inline-literal syntax.  For  exam-
       ple, within the add_executable() command documentation, use

          ``add_executable``

       not

          :command:`add_executable`

       which is used elsewhere.

MODULES
       The Modules directory contains CMake-language .cmake module files.

   Module Documentation
       To  document CMake module Modules/<module-name>.cmake, modify Help/man-
       ual/cmake-modules.7.rst to reference the module in the  toctree  direc-
       tive, in sorted order, as:

          /module/<module-name>

       Then  add  the  module document file Help/module/<module-name>.rst con-
       taining just the line:

          .. cmake-module:: ../../Modules/<module-name>.cmake

       The cmake-module  directive  will  scan  the  module  file  to  extract
       reStructuredText  markup  from comment blocks that start in .rst:.  Add
       to the top of Modules/<module-name>.cmake a Line Comment block  of  the
       form:

          #.rst:
          # <module-name>
          # -------------
          #
          # <reStructuredText documentation of module>

       or a Bracket Comment of the form:

          #[[.rst:
          <module-name>
          -------------

          <reStructuredText documentation of module>
          #]]

       Any number of = may be used in the opening and closing brackets as long
       as they match.  Content on the line containing the closing  bracket  is
       excluded if and only if the line starts in #.

       Additional  such .rst: comments may appear anywhere in the module file.
       All such comments must start with # in the first column.

       For example, a Modules/Findxxx.cmake module may contain:

          #.rst:
          # FindXxx
          # -------
          #
          # This is a cool module.
          # This module does really cool stuff.
          # It can do even more than you think.
          #
          # It even needs two paragraphs to tell you about it.
          # And it defines the following variables:
          #
          # * VAR_COOL: this is great isn't it?
          # * VAR_REALLY_COOL: cool right?

          <code>

          #[========================================[.rst:
          .. command:: xxx_do_something

           This command does something for Xxx::

            xxx_do_something(some arguments)
          #]========================================]
          macro(xxx_do_something)
            <code>
          endmacro()

       After the top documentation block, leave a BLANK line, and then  add  a
       copyright  and licence notice block like this one (change only the year
       range and name)

          #=============================================================================
          # Copyright 2009-2011 Your Name
          #
          # Distributed under the OSI-approved BSD License (the "License");
          # see accompanying file Copyright.txt for details.
          #
          # This software is distributed WITHOUT ANY WARRANTY; without even the
          # implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
          # See the License for more information.
          #=============================================================================
          # (To distribute this file outside of CMake, substitute the full
          #  License text for the above reference.)

       Test the documentation formatting by running cmake --help-module  <mod-
       ule-name>,  and also by enabling the SPHINX_HTML and SPHINX_MAN options
       to build the documentation.  Edit the comments until generated documen-
       tation looks satisfactory.  To have a .cmake file in this directory NOT
       show up in the modules documentation, simply leave  out  the  Help/mod-
       ule/<module-name>.rst file and the Help/manual/cmake-modules.7.rst toc-
       tree entry.

   Find Modules
       A "find module" is a Modules/Find<package>.cmake file to be  loaded  by
       the find_package() command when invoked for <package>.

       The  primary  task  of  a find module is to determine whether a package
       exists on the system, set the <package>_FOUND variable to reflect  this
       and  provide any variables, macros and imported targets required to use
       the package.  A find module  is  useful  in  cases  where  an  upstream
       library does not provide a config file package.

       The  traditional approach is to use variables for everything, including
       libraries and executables: see  the  Standard  Variable  Names  section
       below.   This  is  what  most  of the existing find modules provided by
       CMake do.

       The more modern approach is to behave as much like config file packages
       files  as  possible, by providing imported target.  This has the advan-
       tage of propagating Target Usage Requirements to consumers.

       In either case (or even when providing both variables and imported tar-
       gets),  find  modules  should  provide backwards compatibility with old
       versions that had the same name.

       A FindFoo.cmake module will typically be loaded by the command:

          find_package(Foo [major[.minor[.patch[.tweak]]]]
                       [EXACT] [QUIET] [REQUIRED]
                       [[COMPONENTS] [components...]]
                       [OPTIONAL_COMPONENTS components...]
                       [NO_POLICY_SCOPE])

       See the find_package() documentation for details on what variables  are
       set  for  the find module.  Most of these are dealt with by using Find-
       PackageHandleStandardArgs.

       Briefly, the module should only locate versions of the package compati-
       ble  with  the  requested version, as described by the Foo_FIND_VERSION
       family of variables.  If Foo_FIND_QUIETLY is set  to  true,  it  should
       avoid printing messages, including anything complaining about the pack-
       age not being found.  If Foo_FIND_REQUIRED is set to true,  the  module
       should  issue a FATAL_ERROR if the package cannot be found.  If neither
       are set to true, it should print a non-fatal message if it cannot  find
       the package.

       Packages  that  find  multiple  semi-independent parts (like bundles of
       libraries) should search for the components listed  in  Foo_FIND_COMPO-
       NENTS  if  it  is  set  ,  and  only  set Foo_FOUND to true if for each
       searched-for component <c> that was not found, Foo_FIND_REQUIRED_<c> is
       not  set  to true.  The HANDLE_COMPONENTS argument of find_package_han-
       dle_standard_args() can be used to implement this.

       If Foo_FIND_COMPONENTS is not set, which modules are searched  for  and
       required is up to the find module, but should be documented.

       For internal implementation, it is a generally accepted convention that
       variables starting with underscore are for temporary use only.

       Like all modules, find modules should be properly documented.  To add a
       module to the CMake documentation, follow the steps in the Module Docu-
       mentation section above.

   Standard Variable Names
       For a FindXxx.cmake module that takes the approach of setting variables
       (either  instead  of  or in addition to creating imported targets), the
       following variable names should  be  used  to  keep  things  consistent
       between  find modules.  Note that all variables start with Xxx_ to make
       sure they do not interfere with other find modules; the same considera-
       tion applies to macros, functions and imported targets.

       Xxx_INCLUDE_DIRS
              The  final set of include directories listed in one variable for
              use by client code.  This should not be a cache entry.

       Xxx_LIBRARIES
              The libraries to link against to use Xxx. These  should  include
              full paths.  This should not be a cache entry.

       Xxx_DEFINITIONS
              Definitions  to  use  when  compiling  code  that uses Xxx. This
              really shouldn't include  options  such  as  -DHAS_JPEG  that  a
              client  source-code  file  uses  to  decide  whether to #include
              <jpeg.h>

       Xxx_EXECUTABLE
              Where to find the Xxx tool.

       Xxx_Yyy_EXECUTABLE
              Where to find the Yyy tool that comes with Xxx.

       Xxx_LIBRARY_DIRS
              Optionally, the final set of library directories listed  in  one
              variable  for  use  by  client code.  This should not be a cache
              entry.

       Xxx_ROOT_DIR
              Where to find the base directory of Xxx.

       Xxx_VERSION_Yy
              Expect Version Yy if true. Make sure at most  one  of  these  is
              ever true.

       Xxx_WRAP_Yy
              If False, do not try to use the relevant CMake wrapping command.

       Xxx_Yy_FOUND
              If False, optional Yy part of Xxx sytem is not available.

       Xxx_FOUND
              Set  to  false, or undefined, if we haven't found, or don't want
              to use Xxx.

       Xxx_NOT_FOUND_MESSAGE
              Should be set by config-files  in  the  case  that  it  has  set
              Xxx_FOUND  to  FALSE.   The contained message will be printed by
              the  find_package()  command  and  by  find_package_handle_stan-
              dard_args() to inform the user about the problem.

       Xxx_RUNTIME_LIBRARY_DIRS
              Optionally, the runtime library search path for use when running
              an executable linked to shared libraries.  The  list  should  be
              used   by   user   code   to  create  the  PATH  on  windows  or
              LD_LIBRARY_PATH on UNIX.  This should not be a cache entry.

       Xxx_VERSION
              The full version string of the package found, if any.  Note that
              many existing modules provide Xxx_VERSION_STRING instead.

       Xxx_VERSION_MAJOR
              The major version of the package found, if any.

       Xxx_VERSION_MINOR
              The minor version of the package found, if any.

       Xxx_VERSION_PATCH
              The patch version of the package found, if any.

       The following names should not usually be used in CMakeLists.txt files,
       but are typically cache variables for users to edit and control the be-
       haviour of find modules (like entering the path to a library manually)

       Xxx_LIBRARY
              The  path  of  the Xxx library (as used with find_library(), for
              example).

       Xxx_Yy_LIBRARY
              The path of the Yy library that is part of the  Xxx  system.  It
              may or may not be required to use Xxx.

       Xxx_INCLUDE_DIR
              Where to find headers for using the Xxx library.

       Xxx_Yy_INCLUDE_DIR
              Where  to  find headers for using the Yy library of the Xxx sys-
              tem.

       To prevent users being overwhelmed with settings to configure,  try  to
       keep as many options as possible out of the cache, leaving at least one
       option which can be used to disable use of  the  module,  or  locate  a
       not-found  library (e.g. Xxx_ROOT_DIR).  For the same reason, mark most
       cache options as advanced.  For packages which provide both  debug  and
       release  binaries,  it  is  common  to  create  cache  variables with a
       _LIBRARY_<CONFIG>   suffix,    such    as    Foo_LIBRARY_RELEASE    and
       Foo_LIBRARY_DEBUG.

       While  these  are the standard variable names, you should provide back-
       wards compatibility for any old names that were actually in use.   Make
       sure you comment them as deprecated, so that no-one starts using them.

   A Sample Find Module
       We will describe how to create a simple find module for a library Foo.

       The first thing that is needed is documentation.  CMake's documentation
       system requires you to start the file with a documentation  marker  and
       the name of the module.  You should follow this with a simple statement
       of what the module does.

          #.rst:
          # FindFoo
          # -------
          #
          # Finds the Foo library
          #

       More description may be required  for  some  packages.   If  there  are
       caveats  or  other  details users of the module should be aware of, you
       can add further paragraphs below this.  Then you need to document  what
       variables and imported targets are set by the module, such as

          # This will define the following variables::
          #
          #   Foo_FOUND    - True if the system has the Foo library
          #   Foo_VERSION  - The version of the Foo library which was found
          #
          # and the following imported targets::
          #
          #   Foo::Foo   - The Foo library

       If the package provides any macros, they should be listed here, but can
       be documented where they are defined.   See  the  Module  Documentation
       section above for more details.

       After  the  documentation, leave a blank line, and then add a copyright
       and licence notice block

          #=============================================================================
          # Copyright 2009-2011 Your Name
          #
          # Distributed under the OSI-approved BSD License (the "License");
          # see accompanying file Copyright.txt for details.
          #
          # This software is distributed WITHOUT ANY WARRANTY; without even the
          # implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
          # See the License for more information.
          #=============================================================================
          # (To distribute this file outside of CMake, substitute the full
          #  License text for the above reference.)

       Now the actual libraries and so on have to be  found.   The  code  here
       will  obviously  vary  from  module to module (dealing with that, after
       all, is the point of find modules), but there tends to be a common pat-
       tern for libraries.

       First, we try to use pkg-config to find the library.  Note that we can-
       not rely on this, as it may not be available, but it  provides  a  good
       starting point.

          find_package(PkgConfig)
          pkg_check_modules(PC_Foo QUIET Foo)

       This  should  define  some  variables starting PC_Foo_ that contain the
       information from the Foo.pc file.

       Now we need to find the libraries and include files; we use the  infor-
       mation from pkg-config to provide hints to CMake about where to look.

          find_path(Foo_INCLUDE_DIR
            NAMES foo.h
            PATHS ${PC_Foo_INCLUDE_DIRS}
            PATH_SUFFIXES Foo
          )
          find_library(Foo_LIBRARY
            NAMES foo
            PATHS ${PC_Foo_LIBRARY_DIRS}
          )

       If  you have a good way of getting the version (from a header file, for
       example), you can use that information  to  set  Foo_VERSION  (although
       note  that  find modules have traditionally used Foo_VERSION_STRING, so
       you may want to set both).  Otherwise, attempt to use  the  information
       from pkg-config

          set(Foo_VERSION ${PC_Foo_VERSION})

       Now  we can use FindPackageHandleStandardArgs to do most of the rest of
       the work for us

          include(FindPackageHandleStandardArgs)
          find_package_handle_standard_args(Foo
            FOUND_VAR Foo_FOUND
            REQUIRED_VARS
              Foo_LIBRARY
              Foo_INCLUDE_DIR
            VERSION_VAR Foo_VERSION
          )

       This will check that the REQUIRED_VARS contain values (that do not  end
       in  -NOTFOUND)  and  set  Foo_FOUND  appropriately.  It will also cache
       those values.  If Foo_VERSION is set, and a required version was passed
       to  find_package(), it will check the requested version against the one
       in Foo_VERSION.  It will also print messages as appropriate; note  that
       if  the  package  was  found,  it  will print the contents of the first
       required variable to indicate where it was found.

       At this point, we have to provide a way for users of the find module to
       link  to  the  library  or  libraries  that  were found.  There are two
       approaches, as discussed in the Find Modules section above.  The tradi-
       tional variable approach looks like

          if(Foo_FOUND)
            set(Foo_LIBRARIES ${Foo_LIBRARY})
            set(Foo_INCLUDE_DIRS ${Foo_INCLUDE_DIR})
            set(Foo_DEFINITIONS ${PC_Foo_CFLAGS_OTHER})
          endif()

       If  more  than one library was found, all of them should be included in
       these variables (see the  Standard  Variable  Names  section  for  more
       information).

       When  providing imported targets, these should be namespaced (hence the
       Foo::  prefix);  CMake  will  recognize  that  values  passed  to  tar-
       get_link_libraries()  that  contain :: in their name are supposed to be
       imported targets (rather than just library  names),  and  will  produce
       appropriate diagnostic messages if that target does not exist (see pol-
       icy CMP0028).

          if(Foo_FOUND AND NOT TARGET Foo::Foo)
            add_library(Foo::Foo UNKNOWN IMPORTED)
            set_target_properties(Foo::Foo PROPERTIES
              IMPORTED_LOCATION "${Foo_LIBRARY}"
              INTERFACE_COMPILE_OPTIONS "${PC_Foo_CFLAGS_OTHER}"
              INTERFACE_INCLUDE_DIRECTORIES "${Foo_INCLUDE_DIR}"
            )
          endif()

       One thing to note about this is that the  INTERFACE_INCLUDE_DIRECTORIES
       and similar properties should only contain information about the target
       itself, and not any of its dependencies.  Instead,  those  dependencies
       should  also  be targets, and CMake should be told that they are depen-
       dencies of this target.  CMake will  then  combine  all  the  necessary
       information automatically.

       The  type  of  the IMPORTED target created in the add_library() command
       can always be specified as UNKNOWN type.  This simplifies the  code  in
       cases  where  static  or  shared  variants may be found, and CMake will
       determine the type by inspecting the files.

       If  the  library  is  available  with  multiple   configurations,   the
       IMPORTED_CONFIGURATIONS target property should also be populated:

          if(Foo_FOUND)
            if (NOT TARGET Foo::Foo)
              add_library(Foo::Foo UNKNOWN IMPORTED)
            endif()
            if (Foo_LIBRARY_RELEASE)
              set_property(TARGET Foo::Foo APPEND PROPERTY
                IMPORTED_CONFIGURATIONS RELEASE
              )
              set_target_properties(Foo::Foo PROPERTIES
                IMPORTED_LOCATION_RELEASE "${Foo_LIBRARY_RELEASE}"
              )
            endif()
            if (Foo_LIBRARY_DEBUG)
              set_property(TARGET Foo::Foo APPEND PROPERTY
                IMPORTED_CONFIGURATIONS DEBUG
              )
              set_target_properties(Foo::Foo PROPERTIES
                IMPORTED_LOCATION_DEBUG "${Foo_LIBRARY_DEBUG}"
              )
            endif()
            set_target_properties(Foo::Foo PROPERTIES
              INTERFACE_COMPILE_OPTIONS "${PC_Foo_CFLAGS_OTHER}"
              INTERFACE_INCLUDE_DIRECTORIES "${Foo_INCLUDE_DIR}"
            )
          endif()

       The RELEASE variant should be listed first in the property so that that
       variant is chosen if the user uses a  configuration  which  is  not  an
       exact match for any listed IMPORTED_CONFIGURATIONS.

       Most  of  the  cache variables should be hidden in the ccmake interface
       unless the user explicitly asks to edit them.

          mark_as_advanced(
            Foo_INCLUDE_DIR
            Foo_LIBRARY
          )

       If this module replaces an older version, you should set  compatibility
       variables to cause the least disruption possible.

          # compatibility variables
          set(Foo_VERSION_STRING ${Foo_VERSION})

COPYRIGHT
       2000-2015 Kitware, Inc.



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+-----------------------+
       |ATTRIBUTE TYPE |   ATTRIBUTE VALUE     |
       +---------------+-----------------------+
       |Availability   | developer/build/cmake |
       +---------------+-----------------------+
       |Stability      | Uncommitted           |
       +---------------+-----------------------+
NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source                was                downloaded                from
       http://www.cmake.org/files/v3.9/cmake-3.9.1.tar.gz

       Further information about this software can be found on the open source
       community website at http://www.cmake.org/.



3.3.2                          October 14, 2015             CMAKE-DEVELOPER(7)