lib: use flags_maildir_file

It's a better name. And fix some typos.

lib/message/mu-flags.cc

@@ -138,7 +138,6 @@ test_flags_from_delta_expr()
 			      "-S", Flags::Seen).value() ==
 		      Flags::Unread);
 
-
 	static_assert(flags_from_delta_expr("+R+P-F", Flags::Seen).value() ==
 		      (Flags::Seen|Flags::Passed|Flags::Replied));
 	/* '-B' is invalid */

lib/message/mu-flags.hh

@@ -144,7 +144,6 @@ constexpr std::array<MessageFlagInfo, 14> AllMessageFlagInfos = {{
 	MessageFlagInfo{Flags::HasAttachment,'a', "attach",     MessageFlagCategory::Content,
 		"Has at least one attachment"
 	},
-
 	MessageFlagInfo{Flags::Unread,	 'u', "unread",		MessageFlagCategory::Pseudo,
 		"New or not seen message"
 	},
@@ -289,9 +288,9 @@ flags_from_absolute_expr(std::string_view expr, bool ignore_invalid = false)
  * @param expr delta expression
  * @param flags existing flags
  * @param ignore_invalid if @true, ignore invalid flags, otherwise return
- * nullopt if an invalid flag is encountered
+ * Nothing if an invalid flag is encountered
  *
- * @return new flags, or nullopt in case of error
+ * @return new flags, or Nothing in case of error
  */
 constexpr Option<Flags>
 flags_from_delta_expr(std::string_view expr, Flags flags,
@@ -317,7 +316,6 @@ flags_from_delta_expr(std::string_view expr, Flags flags,
 	}
 
 	return imply_unread(flags);
-
 }
 
 /**
@@ -366,7 +364,7 @@ flags_filter(Flags flags, MessageFlagCategory cat)
  * @return filtered flags
  */
 constexpr Flags
-flags_mail_dir_file(Flags flags)
+flags_maildir_file(Flags flags)
 {
 	for (auto&& info : AllMessageFlagInfos)
 		if (info.category != MessageFlagCategory::Maildir &&

lib/mu-maildir.cc

@@ -421,7 +421,7 @@ Mu::maildir_determine_target(const std::string&	old_path,
 			     Flags		newflags,
 			     bool		new_name)
 {
-	newflags = flags_mail_dir_file(newflags); // filter out irrelevant flags.
+	newflags = flags_maildir_file(newflags); // filter out irrelevant flags.
 
 	/* sanity checks */
 	if (const auto checked{check_determine_target_params(

lib/mu-maildir.hh

@@ -94,7 +94,7 @@ Result<void> maildir_move_message(const std::string& oldpath,
  *
  * @param old_path an absolute file system path to an existing message in an
  * actual maildir
- * @param root_maildir_path the absolete file system path under which
+ * @param root_maildir_path the absolute file system path under which
  * all maildirs live.
  * @param target_maildir the target maildir; note that this the base-level
  * Maildir, ie. /home/user/Maildir/archive, and must _not_ include the
@@ -102,8 +102,8 @@ Result<void> maildir_move_message(const std::string& oldpath,
  * same filesystem. Can be empty if the message should not be moved to
  * a different maildir; note that this may still involve a
  * move to another directory (say, from new/ to cur/)
- * @param flags to set for the target (influences the filename, path). Any none-Maildir/File
+ * @param flags to set for the target (influences the filename, path).
- * flags are ignored.
+ * Any non-Maildir/File flags are ignored.
  * @param new_name whether to change the basename of the file
  *
  * @return Full path name of the target file or an Error