CLI: Reserve arguments that start with ':' for hints

Currently, any argument that starts with ':' that isn't a known hint
will be treated as a tag. After this change, an error is produced.

Hopefully there were not users who were using tags that start with a
colon...

Closes GothenburgBitFactory#348

src/CLI.cpp

@@ -465,11 +465,18 @@ void CLI::canonicalizeNames ()
     }
 
     // Hints.
-    else if (exactMatch ("hint", raw) ||
-             canonicalize (canonical, "hint", raw))
+    else if (0 == raw.compare (0, 1, ":"))
     {
-      a.attribute ("canonical", canonical);
-      a.tag ("HINT");
+      if (exactMatch ("hint", raw) ||
+          canonicalize (canonical, "hint", raw))
+      {
+        a.attribute ("canonical", canonical);
+        a.tag ("HINT");
+      }
+      else
+      {
+        throw format ("'{1}' is an invalid hint.", raw);
+      }
     }
 
     // Extensions.

test/cli.t

@@ -103,6 +103,11 @@ class TestCLI(TestCase):
         code, out, err = self.t.runError("bogus")
         self.assertIn("'bogus' is not a timew command. See 'timew help'.", err)
 
+    def test_TimeWarrior_with_invalid_hint(self):
+        """Call a non-existing TimeWarrior hint should be an error"""
+        code, out, err = self.t.runError("start :invalid_hint")
+        self.assertIn("':invalid_hint'", err)
+
 
 if __name__ == "__main__":
     from simpletap import TAPTestRunner