cmake: Improve user error feedback when -H$ZEPHYR_BASE is specified

Users are sometimes mistakenly invoking cmake with $ZEPHYR_BASE set as
the source directory.

This user-error can occur if the user believes that the toplevel
CMakeLists.txt file is at the root of the repo, or if the user uses
the wrong path when invoking cmake.

The error given when this user-error occurs is cryptic and undefined,
so we replace it with what should be an easy-to-understand error
message.

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>
1 file changed