CPack add necessary check to detect/warns/error on ABSOLUTE DESTINATION

The [usually] wrong usage of absolute DESTINATION in INSTALL rules
keeps popping-up on the ML. We shall have some way to:
  1) easily detect it.
  2) forbids this for some CPack generator like NSIS
In fact it should certainly be forbidden for *any* generators
when used on Windows but we may implements that on top of the current
patch.
The patch ask the task to the generated cmake_install.cmake scripts.
Those scripts are a little bit more complicated with that but
iff there are absolute DESTINATION. This cost nothing if relative
DESTINATION are used.
Two new vars are introduced (and documented to handle that):
CPACK_WARN_ON_ABSOLUTE_INSTALL_DESTINATION
and
CPACK_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION

1 files changed, 9 insertions, 0 deletions

diff --git a/Source/cmInstallGenerator.cxx b/Source/cmInstallGenerator.cxx
index 807168e..2150ec1 100644
--- a/Source/cmInstallGenerator.cxx
+++ b/Source/cmInstallGenerator.cxx
@@ -80,6 +80,15 @@ void cmInstallGenerator
                  }
              }
      os << "\")\n";
+     os << indent << "IF (CPACK_WARN_ON_ABSOLUTE_INSTALL_DESTINATION)\n";
+     os << indent << indent << "message(WARNING \"ABSOLUTE path INSTALL "
+        << "DESTINATION : ${CPACK_ABSOLUTE_DESTINATION_FILES}\")\n";
+     os << indent << "ENDIF (CPACK_WARN_ON_ABSOLUTE_INSTALL_DESTINATION)\n";
+
+     os << indent << "IF (CPACK_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION)\n";
+     os << indent << indent << "message(FATAL_ERROR \"ABSOLUTE path INSTALL "
+        << "DESTINATION forbidden (by CPack): ${CPACK_ABSOLUTE_DESTINATION_FILES}\")\n";
+     os << indent << "ENDIF (CPACK_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION)\n";
      }
   os << "FILE(INSTALL DESTINATION \"" << dest << "\" TYPE " << stype.c_str();
   if(optional)