Add the INTERFACE_SYSTEM_INCLUDE_DIRECTORIES target property.

Unlike other target properties, this does not have a corresponding
non-INTERFACE variant.

This allows propagation of system attribute on include directories
from link dependents.

1 files changed, 8 insertions, 0 deletions

diff --git a/Source/cmTargetIncludeDirectoriesCommand.h b/Source/cmTargetIncludeDirectoriesCommand.h
index a84ddd0..2968618 100644
--- a/Source/cmTargetIncludeDirectoriesCommand.h
+++ b/Source/cmTargetIncludeDirectoriesCommand.h
@@ -71,6 +71,14 @@ public:
       "The following arguments specify include directories.  Specified "
       "include directories may be absolute paths or relative paths.  "
       "Repeated calls for the same <target> append items in the order called."
+      "If SYSTEM is specified, the compiler will be told the "
+      "directories are meant as system include directories on some "
+      "platforms (signalling this setting might achieve effects such as "
+      "the compiler skipping warnings, or these fixed-install system files "
+      "not being considered in dependency calculations - see compiler "
+      "docs).  If SYSTEM is used together with PUBLIC or INTERFACE, the "
+      "INTERFACE_SYSTEM_INCLUDE_DIRECTORIES target property will be "
+      "populated with the specified directories."
       "\n"
       "Arguments to target_include_directories may use \"generator "
       "expressions\" with the syntax \"$<...>\".  "