added FindGlog.cmake

I had some problem with Glog that I finally fixed by adding this FindGlog.cmake CMakeList is modified also : tests are built only if Glog is found.

Should compile fine on team's machine but a fast check would be good.

cmake_modules/FindGlog.cmake

+# Ceres Solver - A fast non-linear least squares minimizer
+# Copyright 2015 Google Inc. All rights reserved.
+# http://ceres-solver.org/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+#   this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+# * Neither the name of Google Inc. nor the names of its contributors may be
+#   used to endorse or promote products derived from this software without
+#   specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+# Author: alexs.mac@gmail.com (Alex Stewart)
+#
+
+# FindGlog.cmake - Find Google glog logging library.
+#
+# This module defines the following variables:
+#
+# GLOG_FOUND: TRUE iff glog is found.
+# GLOG_INCLUDE_DIRS: Include directories for glog.
+# GLOG_LIBRARIES: Libraries required to link glog.
+# FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION: True iff the version of glog found
+#                                           was built & installed / exported
+#                                           as a CMake package.
+#
+# The following variables control the behaviour of this module:
+#
+# GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION: TRUE/FALSE, iff TRUE then
+#                           then prefer using an exported CMake configuration
+#                           generated by glog > 0.3.4 over searching for the
+#                           glog components manually.  Otherwise (FALSE)
+#                           ignore any exported glog CMake configurations and
+#                           always perform a manual search for the components.
+#                           Default: TRUE iff user does not define this variable
+#                           before we are called, and does NOT specify either
+#                           GLOG_INCLUDE_DIR_HINTS or GLOG_LIBRARY_DIR_HINTS
+#                           otherwise FALSE.
+# GLOG_INCLUDE_DIR_HINTS: List of additional directories in which to
+#                         search for glog includes, e.g: /timbuktu/include.
+# GLOG_LIBRARY_DIR_HINTS: List of additional directories in which to
+#                         search for glog libraries, e.g: /timbuktu/lib.
+#
+# The following variables are also defined by this module, but in line with
+# CMake recommended FindPackage() module style should NOT be referenced directly
+# by callers (use the plural variables detailed above instead).  These variables
+# do however affect the behaviour of the module via FIND_[PATH/LIBRARY]() which
+# are NOT re-called (i.e. search for library is not repeated) if these variables
+# are set with valid values _in the CMake cache_. This means that if these
+# variables are set directly in the cache, either by the user in the CMake GUI,
+# or by the user passing -DVAR=VALUE directives to CMake when called (which
+# explicitly defines a cache variable), then they will be used verbatim,
+# bypassing the HINTS variables and other hard-coded search locations.
+#
+# GLOG_INCLUDE_DIR: Include directory for glog, not including the
+#                   include directory of any dependencies.
+# GLOG_LIBRARY: glog library, not including the libraries of any
+#               dependencies.
+
+# Reset CALLERS_CMAKE_FIND_LIBRARY_PREFIXES to its value when
+# FindGlog was invoked.
+macro(GLOG_RESET_FIND_LIBRARY_PREFIX)
+  if (MSVC AND CALLERS_CMAKE_FIND_LIBRARY_PREFIXES)
+    set(CMAKE_FIND_LIBRARY_PREFIXES "${CALLERS_CMAKE_FIND_LIBRARY_PREFIXES}")
+  endif()
+endmacro(GLOG_RESET_FIND_LIBRARY_PREFIX)
+
+# Called if we failed to find glog or any of it's required dependencies,
+# unsets all public (designed to be used externally) variables and reports
+# error message at priority depending upon [REQUIRED/QUIET/<NONE>] argument.
+macro(GLOG_REPORT_NOT_FOUND REASON_MSG)
+  unset(GLOG_FOUND)
+  unset(GLOG_INCLUDE_DIRS)
+  unset(GLOG_LIBRARIES)
+  # Make results of search visible in the CMake GUI if glog has not
+  # been found so that user does not have to toggle to advanced view.
+  mark_as_advanced(CLEAR GLOG_INCLUDE_DIR
+                         GLOG_LIBRARY)
+
+  glog_reset_find_library_prefix()
+
+  # Note <package>_FIND_[REQUIRED/QUIETLY] variables defined by FindPackage()
+  # use the camelcase library name, not uppercase.
+  if (Glog_FIND_QUIETLY)
+    message(STATUS "Failed to find glog - " ${REASON_MSG} ${ARGN})
+  elseif (Glog_FIND_REQUIRED)
+    message(FATAL_ERROR "Failed to find glog - " ${REASON_MSG} ${ARGN})
+  else()
+    # Neither QUIETLY nor REQUIRED, use no priority which emits a message
+    # but continues configuration and allows generation.
+    message("-- Failed to find glog - " ${REASON_MSG} ${ARGN})
+  endif ()
+  return()
+endmacro(GLOG_REPORT_NOT_FOUND)
+
+# Protect against any alternative find_package scripts for this library having
+# been called previously (in a client project) which set GLOG_FOUND, but not
+# the other variables we require / set here which could cause the search logic
+# here to fail.
+unset(GLOG_FOUND)
+
+# -----------------------------------------------------------------
+# By default, if the user has expressed no preference for using an exported
+# glog CMake configuration over performing a search for the installed
+# components, and has not specified any hints for the search locations, then
+# prefer a glog exported configuration if available.
+if (NOT DEFINED GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION
+    AND NOT GLOG_INCLUDE_DIR_HINTS
+    AND NOT GLOG_LIBRARY_DIR_HINTS)
+  message(STATUS "No preference for use of exported glog CMake configuration "
+    "set, and no hints for include/library directories provided. "
+    "Defaulting to preferring an installed/exported glog CMake configuration "
+    "if available.")
+  set(GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION TRUE)
+endif()
+
+if (GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION)
+  # Try to find an exported CMake configuration for glog, as generated by
+  # glog versions > 0.3.4
+  #
+  # We search twice, s/t we can invert the ordering of precedence used by
+  # find_package() for exported package build directories, and installed
+  # packages (found via CMAKE_SYSTEM_PREFIX_PATH), listed as items 6) and 7)
+  # respectively in [1].
+  #
+  # By default, exported build directories are (in theory) detected first, and
+  # this is usually the case on Windows.  However, on OS X & Linux, the install
+  # path (/usr/local) is typically present in the PATH environment variable
+  # which is checked in item 4) in [1] (i.e. before both of the above, unless
+  # NO_SYSTEM_ENVIRONMENT_PATH is passed).  As such on those OSs installed
+  # packages are usually detected in preference to exported package build
+  # directories.
+  #
+  # To ensure a more consistent response across all OSs, and as users usually
+  # want to prefer an installed version of a package over a locally built one
+  # where both exist (esp. as the exported build directory might be removed
+  # after installation), we first search with NO_CMAKE_PACKAGE_REGISTRY which
+  # means any build directories exported by the user are ignored, and thus
+  # installed directories are preferred.  If this fails to find the package
+  # we then research again, but without NO_CMAKE_PACKAGE_REGISTRY, so any
+  # exported build directories will now be detected.
+  #
+  # To prevent confusion on Windows, we also pass NO_CMAKE_BUILDS_PATH (which
+  # is item 5) in [1]), to not preferentially use projects that were built
+  # recently with the CMake GUI to ensure that we always prefer an installed
+  # version if available.
+  #
+  # NOTE: We use the NAMES option as glog erroneously uses 'google-glog' as its
+  #       project name when built with CMake, but exports itself as just 'glog'.
+  #       On Linux/OS X this does not break detection as the project name is
+  #       not used as part of the install path for the CMake package files,
+  #       e.g. /usr/local/lib/cmake/glog, where the <glog> suffix is hardcoded
+  #       in glog's CMakeLists.  However, on Windows the project name *is*
+  #       part of the install prefix: C:/Program Files/google-glog/[include,lib].
+  #       However, by default CMake checks:
+  #       C:/Program Files/<FIND_PACKAGE_ARGUMENT_NAME='glog'> which does not
+  #       exist and thus detection fails.  Thus we use the NAMES to force the
+  #       search to use both google-glog & glog.
+  #
+  # [1] http://www.cmake.org/cmake/help/v2.8.11/cmake.html#command:find_package
+  find_package(glog QUIET
+                    NAMES google-glog glog
+                    NO_MODULE
+                    NO_CMAKE_PACKAGE_REGISTRY
+                    NO_CMAKE_BUILDS_PATH)
+  if (glog_FOUND)
+    message(STATUS "Found installed version of glog: ${glog_DIR}")
+  else()
+    # Failed to find an installed version of glog, repeat search allowing
+    # exported build directories.
+    message(STATUS "Failed to find installed glog CMake configuration, "
+      "searching for glog build directories exported with CMake.")
+    # Again pass NO_CMAKE_BUILDS_PATH, as we know that glog is exported and
+    # do not want to treat projects built with the CMake GUI preferentially.
+    find_package(glog QUIET
+                      NAMES google-glog glog
+                      NO_MODULE
+                      NO_CMAKE_BUILDS_PATH)
+    if (glog_FOUND)
+      message(STATUS "Found exported glog build directory: ${glog_DIR}")
+    endif(glog_FOUND)
+  endif(glog_FOUND)
+
+  set(FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION ${glog_FOUND})
+
+  if (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
+    message(STATUS "Detected glog version: ${glog_VERSION}")
+    set(GLOG_FOUND ${glog_FOUND})
+    # glog wraps the include directories into the exported glog::glog target.
+    set(GLOG_INCLUDE_DIR "")
+    set(GLOG_LIBRARY glog::glog)
+  else (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
+    message(STATUS "Failed to find an installed/exported CMake configuration "
+      "for glog, will perform search for installed glog components.")
+  endif (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
+endif(GLOG_PREFER_EXPORTED_GLOG_CMAKE_CONFIGURATION)
+
+if (NOT GLOG_FOUND)
+  # Either failed to find an exported glog CMake configuration, or user
+  # told us not to use one.  Perform a manual search for all glog components.
+
+  # Handle possible presence of lib prefix for libraries on MSVC, see
+  # also GLOG_RESET_FIND_LIBRARY_PREFIX().
+  if (MSVC)
+    # Preserve the caller's original values for CMAKE_FIND_LIBRARY_PREFIXES
+    # s/t we can set it back before returning.
+    set(CALLERS_CMAKE_FIND_LIBRARY_PREFIXES "${CMAKE_FIND_LIBRARY_PREFIXES}")
+    # The empty string in this list is important, it represents the case when
+    # the libraries have no prefix (shared libraries / DLLs).
+    set(CMAKE_FIND_LIBRARY_PREFIXES "lib" "" "${CMAKE_FIND_LIBRARY_PREFIXES}")
+  endif (MSVC)
+
+  # Search user-installed locations first, so that we prefer user installs
+  # to system installs where both exist.
+  list(APPEND GLOG_CHECK_INCLUDE_DIRS
+    /usr/local/include
+    /usr/local/homebrew/include # Mac OS X
+    /opt/local/var/macports/software # Mac OS X.
+    /opt/local/include
+    /usr/include)
+  # Windows (for C:/Program Files prefix).
+  list(APPEND GLOG_CHECK_PATH_SUFFIXES
+    glog/include
+    glog/Include
+    Glog/include
+    Glog/Include
+    google-glog/include # CMake installs with project name prefix.
+    google-glog/Include)
+
+  list(APPEND GLOG_CHECK_LIBRARY_DIRS
+    /usr/local/lib
+    /usr/local/homebrew/lib # Mac OS X.
+    /opt/local/lib
+    /usr/lib)
+  # Windows (for C:/Program Files prefix).
+  list(APPEND GLOG_CHECK_LIBRARY_SUFFIXES
+    glog/lib
+    glog/Lib
+    Glog/lib
+    Glog/Lib
+    google-glog/lib # CMake installs with project name prefix.
+    google-glog/Lib)
+
+  # Search supplied hint directories first if supplied.
+  find_path(GLOG_INCLUDE_DIR
+    NAMES glog/logging.h
+    HINTS ${GLOG_INCLUDE_DIR_HINTS}
+    PATHS ${GLOG_CHECK_INCLUDE_DIRS}
+    PATH_SUFFIXES ${GLOG_CHECK_PATH_SUFFIXES})
+  if (NOT GLOG_INCLUDE_DIR OR
+      NOT EXISTS ${GLOG_INCLUDE_DIR})
+    glog_report_not_found(
+      "Could not find glog include directory, set GLOG_INCLUDE_DIR "
+      "to directory containing glog/logging.h")
+  endif (NOT GLOG_INCLUDE_DIR OR
+    NOT EXISTS ${GLOG_INCLUDE_DIR})
+
+  find_library(GLOG_LIBRARY NAMES glog
+    HINTS ${GLOG_LIBRARY_DIR_HINTS}
+    PATHS ${GLOG_CHECK_LIBRARY_DIRS}
+    PATH_SUFFIXES ${GLOG_CHECK_LIBRARY_SUFFIXES})
+  if (NOT GLOG_LIBRARY OR
+      NOT EXISTS ${GLOG_LIBRARY})
+    glog_report_not_found(
+      "Could not find glog library, set GLOG_LIBRARY "
+      "to full path to libglog.")
+  endif (NOT GLOG_LIBRARY OR
+    NOT EXISTS ${GLOG_LIBRARY})
+
+  # Mark internally as found, then verify. GLOG_REPORT_NOT_FOUND() unsets
+  # if called.
+  set(GLOG_FOUND TRUE)
+
+  # Glog does not seem to provide any record of the version in its
+  # source tree, thus cannot extract version.
+
+  # Catch case when caller has set GLOG_INCLUDE_DIR in the cache / GUI and
+  # thus FIND_[PATH/LIBRARY] are not called, but specified locations are
+  # invalid, otherwise we would report the library as found.
+  if (GLOG_INCLUDE_DIR AND
+      NOT EXISTS ${GLOG_INCLUDE_DIR}/glog/logging.h)
+    glog_report_not_found(
+      "Caller defined GLOG_INCLUDE_DIR:"
+      " ${GLOG_INCLUDE_DIR} does not contain glog/logging.h header.")
+  endif (GLOG_INCLUDE_DIR AND
+    NOT EXISTS ${GLOG_INCLUDE_DIR}/glog/logging.h)
+  # TODO: This regex for glog library is pretty primitive, we use lowercase
+  #       for comparison to handle Windows using CamelCase library names, could
+  #       this check be better?
+  string(TOLOWER "${GLOG_LIBRARY}" LOWERCASE_GLOG_LIBRARY)
+  if (GLOG_LIBRARY AND
+      NOT "${LOWERCASE_GLOG_LIBRARY}" MATCHES ".*glog[^/]*")
+    glog_report_not_found(
+      "Caller defined GLOG_LIBRARY: "
+      "${GLOG_LIBRARY} does not match glog.")
+  endif (GLOG_LIBRARY AND
+    NOT "${LOWERCASE_GLOG_LIBRARY}" MATCHES ".*glog[^/]*")
+
+  glog_reset_find_library_prefix()
+
+endif(NOT GLOG_FOUND)
+
+# Set standard CMake FindPackage variables if found.
+if (GLOG_FOUND)
+  set(GLOG_INCLUDE_DIRS ${GLOG_INCLUDE_DIR})
+  set(GLOG_LIBRARIES ${GLOG_LIBRARY})
+endif (GLOG_FOUND)
+
+# If we are using an exported CMake glog target, the include directories are
+# wrapped into the target itself, and do not have to be (and are not)
+# separately specified.  In which case, we should not add GLOG_INCLUDE_DIRS
+# to the list of required variables in order that glog be reported as found.
+if (FOUND_INSTALLED_GLOG_CMAKE_CONFIGURATION)
+  set(GLOG_REQUIRED_VARIABLES GLOG_LIBRARIES)
+else()
+  set(GLOG_REQUIRED_VARIABLES GLOG_INCLUDE_DIRS GLOG_LIBRARIES)
+endif()
+
+# Handle REQUIRED / QUIET optional arguments.
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Glog DEFAULT_MSG
+  ${GLOG_REQUIRED_VARIABLES})
+
+# Only mark internal variables as advanced if we found glog, otherwise
+# leave them visible in the standard GUI for the user to set manually.
+if (GLOG_FOUND)
+  mark_as_advanced(FORCE GLOG_INCLUDE_DIR
+                         GLOG_LIBRARY
+                         glog_DIR) # Autogenerated by find_package(glog)
+endif (GLOG_FOUND)