sfm: update gflags detection

modules/sfm/CMakeLists.txt

@@ -9,7 +9,7 @@ if(NOT Ceres_FOUND)  # Looks like Ceres find glog on the own, so separate search
   find_package(Glog QUIET)
 endif()
 
-if((gflags_FOUND OR GFLAGS_FOUND) AND (glog_FOUND OR GLOG_FOUND))
+if((gflags_FOUND OR GFLAGS_FOUND OR GFLAGS_INCLUDE_DIRS) AND (glog_FOUND OR GLOG_FOUND OR GLOG_INCLUDE_DIRS))
   set(_fname "${CMAKE_CURRENT_BINARY_DIR}/test_sfm_deps.cpp")
   file(WRITE "${_fname}" "#include <glog/logging.h>\n#include <gflags/gflags.h>\nint main() { (void)(0); return 0; }\n")
   try_compile(SFM_DEPS_OK "${CMAKE_BINARY_DIR}" "${_fname}"

modules/sfm/cmake/FindGflags.cmake

@@ -129,7 +129,11 @@ endmacro(GFLAGS_REPORT_NOT_FOUND)
 macro(GFLAGS_CHECK_VARS_DEFINED)
   foreach(CHECK_VAR ${ARGN})
     if (NOT DEFINED ${CHECK_VAR})
-      message(FATAL_ERROR "Ceres Bug: ${CHECK_VAR} is not defined.")
+      if(NOT Gflags_FIND_REQUIRED)
+        gflags_report_not_found("Ceres Bug: ${CHECK_VAR} is not defined.")
+      else()
+        message(FATAL_ERROR "Ceres Bug: ${CHECK_VAR} is not defined.")
+      endif()
     endif()
   endforeach()
 endmacro(GFLAGS_CHECK_VARS_DEFINED)
@@ -283,7 +287,8 @@ if (NOT DEFINED GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION
   set(GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION TRUE)
 endif()
 
-if (GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION)
+# Wrap into function because gflags_report_not_found() uses "return" statement
+function(__find_exported_gflags)
   # Try to find an exported CMake configuration for gflags, as generated by
   # gflags versions >= 2.1.
   #
@@ -384,9 +389,19 @@ if (GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION)
 
   if (FOUND_INSTALLED_GFLAGS_CMAKE_CONFIGURATION)
     message(STATUS "Detected gflags version: ${gflags_VERSION}")
-    #set(GFLAGS_FOUND ${gflags_FOUND})
-    #set(GFLAGS_INCLUDE_DIR ${gflags_INCLUDE_DIR})
-    #set(GFLAGS_LIBRARY ${gflags_LIBRARIES})
+    if(NOT DEFINED GFLAGS_FOUND AND DEFINED gflags_FOUND)
+      set(GFLAGS_FOUND ${gflags_FOUND})
+    endif()
+    if(NOT DEFINED GFLAGS_INCLUDE_DIR AND DEFINED gflags_INCLUDE_DIR)
+      set(GFLAGS_INCLUDE_DIR ${gflags_INCLUDE_DIR})
+    endif()
+    if(NOT DEFINED GFLAGS_LIBRARY AND DEFINED gflags_LIBRARIES)
+      set(GFLAGS_LIBRARY ${gflags_LIBRARIES})
+    endif()
+
+    if(NOT DEFINED GFLAGS_INCLUDE_DIR)
+      gflags_report_not_found("GFLAGS_INCLUDE_DIR is missing")
+    endif()
 
     # gflags does not export the namespace in their CMake configuration, so
     # use our function to determine what it should be, as it can be either
@@ -406,6 +421,15 @@ if (GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION)
     message(STATUS "Failed to find an installed/exported CMake configuration "
       "for gflags, will perform search for installed gflags components.")
   endif (FOUND_INSTALLED_GFLAGS_CMAKE_CONFIGURATION)
+
+  set(GFLAGS_FOUND "${GFLAGS_FOUND}" PARENT_SCOPE)
+  set(GFLAGS_INCLUDE_DIR "${GFLAGS_INCLUDE_DIR}" PARENT_SCOPE)
+  set(GFLAGS_LIBRARY "${GFLAGS_LIBRARY}" PARENT_SCOPE)
+  set(GFLAGS_NAMESPACE "${GFLAGS_NAMESPACE}" PARENT_SCOPE)
+endfunction()
+
+if (GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION)
+  __find_exported_gflags()
 endif(GFLAGS_PREFER_EXPORTED_GFLAGS_CMAKE_CONFIGURATION)
 
 if (NOT GFLAGS_FOUND)