Found the following significant warnings:
  ../inst/include/CImg.h:224:5: warning: 'long long' is a C++11 extension [-Wc++11-long-long]
  ../inst/include/CImg.h:14876:29: warning: multiple unsequenced modifications to 'ptrs' [-Wunsequenced]
  ../inst/include/CImg.h:15055:19: warning: multiple unsequenced modifications to 'ptrs' [-Wunsequenced]
  ../inst/include/CImg.h:25383:23: warning: unsequenced modification and access to 'right' [-Wunsequenced]
  ../inst/include/CImg.h:32971:35: warning: unsequenced modification and access to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:32971:35: warning: multiple unsequenced modifications to '_n3x' [-Wunsequenced]
  ../inst/include/CImg.h:32971:35: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:32991:40: warning: unsequenced modification and access to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:32991:40: warning: multiple unsequenced modifications to '_n3x' [-Wunsequenced]
  ../inst/include/CImg.h:32991:40: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:33011:35: warning: multiple unsequenced modifications to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:33011:35: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:33025:40: warning: multiple unsequenced modifications to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:33025:40: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:33043:35: warning: multiple unsequenced modifications to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:33043:35: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:33054:40: warning: multiple unsequenced modifications to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:33054:40: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:34067:19: warning: unsequenced modification and access to 'right' [-Wunsequenced]
  ../inst/include/CImg.h:35471:17: warning: multiple unsequenced modifications to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:35471:17: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:35483:17: warning: unsequenced modification and access to '_n2x' [-Wunsequenced]
  ../inst/include/CImg.h:35483:17: warning: multiple unsequenced modifications to '_n3x' [-Wunsequenced]
  ../inst/include/CImg.h:35483:17: warning: unsequenced modification and access to '_n1x' [-Wunsequenced]
  ../inst/include/CImg.h:48268:18: warning: unsequenced modification and access to 'err' [-Wunsequenced]
  ../inst/include/CImg.h:48276:18: warning: unsequenced modification and access to 'err' [-Wunsequenced]
  ../inst/include/CImg.h:48286:22: warning: unsequenced modification and access to 'err' [-Wunsequenced]
  ../inst/include/CImg.h:48470:18: warning: unsequenced modification and access to 'err' [-Wunsequenced]
  ../inst/include/CImg.h:48478:18: warning: unsequenced modification and access to 'err' [-Wunsequenced]
  ../inst/include/CImg.h:48487:20: warning: unsequenced modification and access to 'err' [-Wunsequenced]
See ‘/Users/ripley/R/packages/tests-devel/imager.Rcheck/00install.out’ for details.