Pass ctx to NoSuchOption exceptions

Ensures that exception printing hints about using ``--help`` option.

CHANGES.rst

@@ -8,6 +8,8 @@ Version 7.0
 
 (upcoming release with new features, release date to be decided)
 
+- ``NoSuchOption`` errors take ``ctx`` so that ``--help`` hint gets printed in
+  error output (`#860`_)
 - Non-standalone calls to Context.exit return the exit code, rather than
   calling ``sys.exit`` (`#667`_)(`#533`_)
 - Updated test env matrix. (`#1027`_)

click/parser.py

@@ -321,7 +321,7 @@ def _match_long_opt(self, opt, explicit_value, state):
         if opt not in self._long_opt:
             possibilities = [word for word in self._long_opt
                              if word.startswith(opt)]
-            raise NoSuchOption(opt, possibilities=possibilities)
+            raise NoSuchOption(opt, possibilities=possibilities, ctx=self.ctx)
 
         option = self._long_opt[opt]
         if option.takes_value:
@@ -364,7 +364,7 @@ def _match_short_opt(self, arg, state):
                 if self.ignore_unknown_options:
                     unknown_options.append(ch)
                     continue
-                raise NoSuchOption(opt)
+                raise NoSuchOption(opt, ctx=self.ctx)
             if option.takes_value:
                 # Any characters left in arg?  Pretend they're the
                 # next arg, and stop consuming characters of arg.