Merge pull request #140 from schuhschuh/enh-#117-gflags-subproject-support

These changes improve the CMakeLists.txt of the gflags project to make CMake variables configurable via command-line option -D or super-project settings. Moreover, gflags related variables are only added to the CMake cache when the gflags project is configured as a standalone project. When it is a subproject (cf. #117), the super-project is responsible for setting the configuration variables.

This change set also changes the names of the (exported) target names to gflags[_nothreads]_(static|shared) and the CMake (package) configuration variable names to start with an uppercase prefix "GFLAGS_".

.gitignore

@@ -15,3 +15,4 @@ CMakeFiles/
 /test/gflags_unittest_main.cc
 /test/gflags_unittest-main.cc
 /packages/
+CMakeLists.txt.user

cmake/config.cmake.in

 ## gflags CMake configuration file
 
 # library version information
-set (@PACKAGE_NAME@_VERSION_STRING "@PACKAGE_VERSION@")
-set (@PACKAGE_NAME@_VERSION_MAJOR  @PACKAGE_VERSION_MAJOR@)
-set (@PACKAGE_NAME@_VERSION_MINOR  @PACKAGE_VERSION_MINOR@)
-set (@PACKAGE_NAME@_VERSION_PATCH  @PACKAGE_VERSION_PATCH@)
+set (@PACKAGE_PREFIX@_VERSION_STRING "@PACKAGE_VERSION@")
+set (@PACKAGE_PREFIX@_VERSION_MAJOR  @PACKAGE_VERSION_MAJOR@)
+set (@PACKAGE_PREFIX@_VERSION_MINOR  @PACKAGE_VERSION_MINOR@)
+set (@PACKAGE_PREFIX@_VERSION_PATCH  @PACKAGE_VERSION_PATCH@)
 
 # import targets
-include ("${CMAKE_CURRENT_LIST_DIR}/@PACKAGE_NAME@-export.cmake")
+include ("${CMAKE_CURRENT_LIST_DIR}/@PACKAGE_NAME@-targets.cmake")
 
 # installation prefix
 get_filename_component (CMAKE_CURRENT_LIST_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
@@ -18,94 +18,151 @@ get_filename_component (_INSTALL_PREFIX "${CMAKE_CURRENT_LIST_DIR}/@INSTALL_PREF
 # Newer versions of CMake set the INTERFACE_INCLUDE_DIRECTORIES property
 # of the imported targets. It is hence not necessary to add this path
 # manually to the include search path for targets which link to gflags.
-set (@PACKAGE_NAME@_INCLUDE_DIR "${_INSTALL_PREFIX}/@INCLUDE_INSTALL_DIR@")
+set (@PACKAGE_PREFIX@_INCLUDE_DIR "${_INSTALL_PREFIX}/@INCLUDE_INSTALL_DIR@")
 
-# default settings
-if (NOT DEFINED @PACKAGE_NAME@_SHARED)
-  if (TARGET @PACKAGE_NAME@-static OR TARGET @PACKAGE_NAME@_nothreads-static)
-    set (@PACKAGE_NAME@_SHARED FALSE)
+if (@PACKAGE_NAME@_FIND_COMPONENTS)
+  foreach (@PACKAGE_NAME@_FIND_COMPONENT IN LISTS @PACKAGE_NAME@_FIND_COMPONENTS)
+    if (@PACKAGE_NAME@_FIND_REQUIRED_${@PACKAGE_NAME@_FIND_COMPONENT} AND NOT TARGET @PACKAGE_NAME@_${@PACKAGE_NAME@_FIND_COMPONENT})
+      message (FATAL_ERROR "Package @PACKAGE_NAME@ was installed without required component ${@PACKAGE_NAME@_FIND_COMPONENT}!")
+    endif ()
+  endforeach ()
+  list (GET @PACKAGE_NAME@_FIND_COMPONENTS 0 @PACKAGE_NAME@_FIND_COMPONENT)
+else ()
+  set (@PACKAGE_NAME@_FIND_COMPONENT)
+endif ()
+
+# default settings of @PACKAGE_PREFIX@_SHARED and @PACKAGE_PREFIX@_NOTHREADS
+#
+# It is recommended to use either one of the following find_package commands
+# instead of setting the @PACKAGE_PREFIX@_(SHARED|NOTHREADS) variables:
+# - find_package(@PACKAGE_NAME@ REQUIRED)
+# - find_package(@PACKAGE_NAME@ COMPONENTS nothreads_static)
+# - find_package(@PACKAGE_NAME@ COMPONENTS nothreads_shared)
+# - find_package(@PACKAGE_NAME@ COMPONENTS static)
+# - find_package(@PACKAGE_NAME@ COMPONENTS shared)
+if (NOT DEFINED @PACKAGE_PREFIX@_SHARED)
+  if (DEFINED @PACKAGE_NAME@_SHARED)
+    set (@PACKAGE_PREFIX@_SHARED ${@PACKAGE_NAME@_SHARED})
+  elseif (@PACKAGE_NAME@_FIND_COMPONENT)
+    if (@PACKAGE_NAME@_FIND_COMPONENT MATCHES "shared")
+      set (@PACKAGE_PREFIX@_SHARED TRUE)
+    else ()
+      set (@PACKAGE_PREFIX@_SHARED FALSE)
+    endif ()
+  elseif (TARGET @PACKAGE_NAME@_shared OR TARGET @PACKAGE_NAME@_nothreads_shared)
+    set (@PACKAGE_PREFIX@_SHARED TRUE)
   else ()
-    set (@PACKAGE_NAME@_SHARED TRUE)
+    set (@PACKAGE_PREFIX@_SHARED FALSE)
   endif ()
 endif ()
-if (NOT DEFINED @PACKAGE_NAME@_NOTHREADS)
-  if (TARGET @PACKAGE_NAME@-static OR TARGET @PACKAGE_NAME@-shared)
-    set (@PACKAGE_NAME@_NOTHREADS FALSE)
+if (NOT DEFINED @PACKAGE_PREFIX@_NOTHREADS)
+  if (DEFINED @PACKAGE_NAME@_NOTHREADS)
+    set (@PACKAGE_PREFIX@_NOTHREADS ${@PACKAGE_NAME@_NOTHREADS})
+  elseif (@PACKAGE_NAME@_FIND_COMPONENT)
+    if (@PACKAGE_NAME@_FIND_COMPONENT MATCHES "nothreads")
+      set (@PACKAGE_PREFIX@_NOTHREADS TRUE)
+    else ()
+      set (@PACKAGE_PREFIX@_NOTHREADS FALSE)
+    endif ()
+  elseif (TARGET @PACKAGE_NAME@_static OR TARGET @PACKAGE_NAME@_shared)
+    set (@PACKAGE_PREFIX@_NOTHREADS FALSE)
   else ()
-    set (@PACKAGE_NAME@_NOTHREADS TRUE)
+    set (@PACKAGE_PREFIX@_NOTHREADS TRUE)
   endif ()
 endif ()
 
 # choose imported library target
-if (NOT @PACKAGE_NAME@_TARGET)
-  if (@PACKAGE_NAME@_SHARED)
-    if (@PACKAGE_NAME@_NOTHREADS)
-      set (@PACKAGE_NAME@_TARGET @PACKAGE_NAME@_nothreads-shared)
+if (NOT @PACKAGE_PREFIX@_TARGET)
+  if (@PACKAGE_NAME@_TARGET)
+    set (@PACKAGE_PREFIX@_TARGET ${@PACKAGE_NAME@_TARGET})
+  elseif (@PACKAGE_PREFIX@_SHARED)
+    if (@PACKAGE_PREFIX@_NOTHREADS)
+      set (@PACKAGE_PREFIX@_TARGET @PACKAGE_NAME@_nothreads_shared)
     else ()
-      set (@PACKAGE_NAME@_TARGET @PACKAGE_NAME@-shared)
+      set (@PACKAGE_PREFIX@_TARGET @PACKAGE_NAME@_shared)
     endif ()
   else ()
-    if (@PACKAGE_NAME@_NOTHREADS)
-      set (@PACKAGE_NAME@_TARGET @PACKAGE_NAME@_nothreads-static)
+    if (@PACKAGE_PREFIX@_NOTHREADS)
+      set (@PACKAGE_PREFIX@_TARGET @PACKAGE_NAME@_nothreads_static)
     else ()
-      set (@PACKAGE_NAME@_TARGET @PACKAGE_NAME@-static)
+      set (@PACKAGE_PREFIX@_TARGET @PACKAGE_NAME@_static)
     endif ()
   endif ()
 endif ()
-if (NOT TARGET ${@PACKAGE_NAME@_TARGET})
-  message (FATAL_ERROR "Your @PACKAGE_NAME@ installation does not contain a ${@PACKAGE_NAME@_TARGET} library target!"
-                       " Try a different combination of @PACKAGE_NAME@_SHARED and @PACKAGE_NAME@_NOTHREADS.")
+if (NOT TARGET ${@PACKAGE_PREFIX@_TARGET})
+  message (FATAL_ERROR "Your @PACKAGE_NAME@ installation does not contain a ${@PACKAGE_PREFIX@_TARGET} library target!"
+                       " Try a different combination of @PACKAGE_PREFIX@_SHARED and @PACKAGE_PREFIX@_NOTHREADS.")
 endif ()
 
 # add more convenient "@PACKAGE_NAME@" import target
 if (NOT TARGET @PACKAGE_NAME@)
-  if (@PACKAGE_NAME@_SHARED)
+  if (@PACKAGE_PREFIX@_SHARED)
     add_library (@PACKAGE_NAME@ SHARED IMPORTED)
   else ()
     add_library (@PACKAGE_NAME@ STATIC IMPORTED)
   endif ()
-  # INTERFACE_INCLUDE_DIRECTORIES
-  get_target_property (_@PACKAGE_NAME@_INCLUDES ${@PACKAGE_NAME@_TARGET} INTERFACE_INCLUDE_DIRECTORIES)
-  if (_@PACKAGE_NAME@_INCLUDES)
-    set_target_properties(@PACKAGE_NAME@ PROPERTIES
-      INTERFACE_INCLUDE_DIRECTORIES "${_@PACKAGE_NAME@_INCLUDES}"
-    )
-  endif ()
-  unset (_@PACKAGE_NAME@_INCLUDES)
-  # set configuration specific properties
-  get_target_property (_@PACKAGE_NAME@_CONFIGURATIONS ${@PACKAGE_NAME@_TARGET} IMPORTED_CONFIGURATIONS)
-  set_target_properties (@PACKAGE_NAME@ PROPERTIES IMPORTED_CONFIGURATIONS "${_@PACKAGE_NAME@_CONFIGURATIONS}")
-  foreach (_@PACKAGE_NAME@_CONFIG IN LISTS _@PACKAGE_NAME@_CONFIGURATIONS)
-    # IMPORTED_LOCATION_<config>
-    get_target_property (_@PACKAGE_NAME@_LOCATION ${@PACKAGE_NAME@_TARGET} IMPORTED_LOCATION_${_@PACKAGE_NAME@_CONFIG})
-    if (_@PACKAGE_NAME@_LOCATION)
+  # copy INTERFACE_* properties
+  foreach (_@PACKAGE_PREFIX@_PROPERTY_NAME IN ITEMS
+    COMPILE_DEFINITIONS
+    COMPILE_FEATURES
+    COMPILE_OPTIONS
+    INCLUDE_DIRECTORIES
+    LINK_LIBRARIES
+    POSITION_INDEPENDENT_CODE
+  )
+    get_target_property (_@PACKAGE_PREFIX@_PROPERTY_VALUE ${@PACKAGE_PREFIX@_TARGET} INTERFACE_${_@PACKAGE_PREFIX@_PROPERTY_NAME})
+    if (_@PACKAGE_PREFIX@_PROPERTY_VALUE)
       set_target_properties(@PACKAGE_NAME@ PROPERTIES
-        IMPORTED_LOCATION_${_@PACKAGE_NAME@_CONFIG} "${_@PACKAGE_NAME@_LOCATION}"
+        INTERFACE_${_@PACKAGE_PREFIX@_PROPERTY_NAME} "${_@PACKAGE_PREFIX@_PROPERTY_VALUE}"
       )
     endif ()
-    unset (_@PACKAGE_NAME@_LOCATION)
-    # IMPORTED_LINK_INTERFACE_LANGUAGES_<config> (static)
-    get_target_property (_@PACKAGE_NAME@_LANGUAGES ${@PACKAGE_NAME@_TARGET} IMPORTED_LINK_INTERFACE_LANGUAGES_${_@PACKAGE_NAME@_CONFIG})
-    if (_@PACKAGE_NAME@_LANGUAGES)
-      set_target_properties(@PACKAGE_NAME@ PROPERTIES
-        IMPORTED_LINK_INTERFACE_LANGUAGES_${_@PACKAGE_NAME@_CONFIG} "${_@PACKAGE_NAME@_LANGUAGES}"
-      )
-    endif ()
-    unset (_@PACKAGE_NAME@_LANGUAGES)
-    # IMPORTED_SONAME_<config> (shared)
-    get_target_property (_@PACKAGE_NAME@_SONAME ${@PACKAGE_NAME@_TARGET} IMPORTED_SONAME_${_@PACKAGE_NAME@_CONFIG})
-    if (_@PACKAGE_NAME@_SONAME)
-      set_target_properties(@PACKAGE_NAME@ PROPERTIES
-        IMPORTED_SONAME_${_@PACKAGE_NAME@_CONFIG} "${_@PACKAGE_NAME@_SONAME}"
-      )
-    endif ()
-    unset (_@PACKAGE_NAME@_SONAME)
   endforeach ()
-  unset (_@PACKAGE_NAME@_CONFIGURATIONS)
+  # copy IMPORTED_*_<CONFIG> properties
+  get_target_property (_@PACKAGE_PREFIX@_CONFIGURATIONS ${@PACKAGE_PREFIX@_TARGET} IMPORTED_CONFIGURATIONS)
+  set_target_properties (@PACKAGE_NAME@ PROPERTIES IMPORTED_CONFIGURATIONS "${_@PACKAGE_PREFIX@_CONFIGURATIONS}")
+  foreach (_@PACKAGE_PREFIX@_PROPERTY_NAME IN ITEMS
+    LOCATION
+    LINK_DEPENDENT_LIBRARIES
+    LINK_INTERFACE_LIBRARIES
+    LINK_INTERFACE_LANGUAGES 
+    LINK_INTERFACE_MULTIPLICITY
+    NO_SONAME
+    SONAME
+  )
+    foreach (_@PACKAGE_PREFIX@_CONFIG IN LISTS _@PACKAGE_PREFIX@_CONFIGURATIONS)
+      get_target_property (_@PACKAGE_PREFIX@_PROPERTY_VALUE ${@PACKAGE_PREFIX@_TARGET} IMPORTED_${_@PACKAGE_PREFIX@_PROPERTY_NAME}_${_@PACKAGE_PREFIX@_CONFIG})
+      if (_@PACKAGE_PREFIX@_PROPERTY_VALUE)
+        set_target_properties(@PACKAGE_NAME@ PROPERTIES
+          IMPORTED_${_@PACKAGE_PREFIX@_PROPERTY_NAME}_${_@PACKAGE_PREFIX@_CONFIG} "${_@PACKAGE_PREFIX@_PROPERTY_VALUE}"
+        )
+      endif ()
+    endforeach ()
+  endforeach ()
+  unset (_@PACKAGE_PREFIX@_CONFIGURATIONS)
+  unset (_@PACKAGE_PREFIX@_CONFIG)
+  unset (_@PACKAGE_PREFIX@_PROPERTY_NAME)
+  unset (_@PACKAGE_PREFIX@_PROPERTY_VALUE)
 endif ()
 
 # alias for default import target to be compatible with older CMake package configurations
-set (@PACKAGE_NAME@_LIBRARIES "${@PACKAGE_NAME@_TARGET}")
+set (@PACKAGE_PREFIX@_LIBRARIES "${@PACKAGE_PREFIX@_TARGET}")
+
+# set @PACKAGE_NAME@_* variables for backwards compatibility
+if (NOT "^@PACKAGE_NAME@$" STREQUAL "^@PACKAGE_PREFIX@$")
+  foreach (_@PACKAGE_PREFIX@_VARIABLE IN ITEMS
+    VERSION_STRING
+    VERSION_MAJOR
+    VERSION_MINOR
+    VERSION_PATCH
+    INCLUDE_DIR
+    LIBRARIES
+    TARGET
+  )
+    set (@PACKAGE_NAME@_${_@PACKAGE_PREFIX@_VARIABLE} "${@PACKAGE_PREFIX@_${_@PACKAGE_PREFIX@_VARIABLE}}")
+  endforeach ()
+  unset (_@PACKAGE_PREFIX@_VARIABLE)
+endif ()
 
 # unset private variables
+unset (@PACKAGE_NAME@_FIND_COMPONENT)
 unset (_INSTALL_PREFIX)

cmake/utils.cmake

@@ -11,7 +11,7 @@ macro (bool_to_int VAR)
 endmacro ()
 
 # ----------------------------------------------------------------------------
-## Extract version numbers from version string.
+## Extract version numbers from version string
 function (version_numbers version major minor patch)
   if (version MATCHES "([0-9]+)(\\.[0-9]+)?(\\.[0-9]+)?(rc[1-9][0-9]*|[a-z]+)?")
     if (CMAKE_MATCH_1)
@@ -41,6 +41,73 @@ function (version_numbers version major minor patch)
   set ("${patch}" "${_patch}" PARENT_SCOPE)
 endfunction ()
 
+# ----------------------------------------------------------------------------
+## Determine if cache entry exists
+macro (gflags_is_cached retvar varname)
+  if (DEFINED ${varname})
+    get_property (${retvar} CACHE ${varname} PROPERTY TYPE SET)
+  else ()
+    set (${retvar} FALSE)
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Add gflags configuration variable
+#
+# The default value of the (cached) configuration value can be overridden either
+# on the CMake command-line or the super-project by setting the GFLAGS_<varname>
+# variable. When gflags is a subproject of another project (GFLAGS_IS_SUBPROJECT),
+# the variable is not added to the CMake cache. Otherwise it is cached.
+macro (gflags_define type varname docstring default)
+  if (ARGC GREATER 5)
+    message (FATAL_ERROR "gflags_variable: Too many macro arguments")
+  endif ()
+  if (NOT DEFINED GFLAGS_${varname})
+    if (GFLAGS_IS_SUBPROJECT AND ARGC EQUAL 5)
+      set (GFLAGS_${varname} "${ARGV4}")
+    else ()
+      set (GFLAGS_${varname} "${default}")
+    endif ()
+  endif ()
+  if (GFLAGS_IS_SUBPROJECT)
+    if (NOT DEFINED ${varname})
+      set (${varname} "${GFLAGS_${varname}}")
+    endif ()
+  else ()
+    set (${varname} "${GFLAGS_${varname}}" CACHE ${type} "${docstring}")
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Set property of cached gflags configuration variable
+macro (gflags_property varname property value)
+  gflags_is_cached (_cached ${varname})
+  if (_cached)
+    if (property STREQUAL ADVANCED)
+      if (${value})
+        mark_as_advanced (FORCE ${varname})
+      else ()
+        mark_as_advanced (CLEAR ${varname})
+      endif ()
+    else ()
+      set_property (CACHE ${varname} PROPERTY "${property}" "${value}")
+    endif ()
+  endif ()
+  unset (_cached)
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Modify value of gflags configuration variable
+macro (gflags_set varname value)
+  gflags_is_cached (_cached ${varname})
+  if (_cached)
+    set_property (CACHE ${varname} PROPERTY VALUE "${value}")
+  else ()
+    set (${varname} "${value}")
+  endif ()
+  unset (_cached)
+endmacro ()
+
 # ----------------------------------------------------------------------------
 ## Configure public header files
 function (configure_headers out)

test/CMakeLists.txt

@@ -22,9 +22,9 @@ else ()
   set (type static)
 endif ()
 if (BUILD_gflags_LIB)
-  link_libraries (gflags-${type})
+  link_libraries (gflags_${type})
 else ()
-  link_libraries (gflags_nothreads-${type})
+  link_libraries (gflags_nothreads_${type})
 endif ()
 
 # ----------------------------------------------------------------------------

test/nc/CMakeLists.txt

 ## gflags negative compilation tests
 
-cmake_minimum_required (VERSION 2.8)
+cmake_minimum_required (VERSION 2.8.12 FATAL_ERROR)
 
 if (NOT TEST_NAME)
   message (FATAL_ERROR "Missing TEST_NAME CMake flag")
@@ -13,4 +13,4 @@ find_package (gflags REQUIRED)
 include_directories ("${CMAKE_CURRENT_SOURCE_DIR}/..")
 add_definitions (-DTEST_${TEST_NAME_UPPER})
 add_executable (gflags_${TEST_NAME} gflags_nc.cc)
-target_link_libraries(gflags_${TEST_NAME} ${gflags_LIBRARIES})
+target_link_libraries(gflags_${TEST_NAME} gflags)