case-insensitive field name for comment deletion

opustags.1

@@ -68,8 +68,8 @@ Use \fB-y\fP to allow overwriting.
 Note that this option is not needed when the output is a special file like \fI/dev/null\fP.
 .TP
 .B \-d, \-\-delete \fIFIELD\fP
-Delete all the tags whose field name is \fIFIELD\fP. They may be several one of them, though usually
-there is only one of each type.
+Delete all the tags whose field name is \fIFIELD\fP. The field names are case-insensitive, and
+expected to be ASCII.
 .TP
 .B \-a, \-\-add \fIFIELD=VALUE\fP
 Add a tag. Note that multiple tags with the same field name are perfectly acceptable, so you can add

src/cli.cc

@@ -213,7 +213,7 @@ void ot::delete_comments(std::list<std::string>& comments, const std::string& fi
 		auto current = it++;
 		if (current->size() > field_len + 1 &&
 		    (*current)[field_len] == '=' &&
-		    strncmp(current->data(), field_name.data(), field_len) == 0)
+		    strncasecmp(current->data(), field_name.data(), field_len) == 0)
 			comments.erase(current);
 	}
 }

src/opustags.h

@@ -462,7 +462,6 @@ status read_comments(FILE* input, std::list<std::string>& comments);
 /**
  * Remove all the comments whose field name is equal to the special one, case-sensitive.
  *
- * \todo Become case-insensitive.
  * \todo Accept fields like X=Y to remove only comments X=Y, instead of all X.
  */
 void delete_comments(std::list<std::string>& comments, const std::string& field_name);

t/cli.cc

@@ -104,7 +104,7 @@ static void check_delete_comments()
 		throw failure("should not have deleted anything");
 
 	ot::delete_comments(edited, "Title");
-	C expected = {"TITLE=X", "ARTIST=A", "artIst=B"};
+	C expected = {"ARTIST=A", "artIst=B"};
 	if (!std::equal(edited.begin(), edited.end(), expected.begin(), expected.end()))
 		throw failure("did not delete Title correctly");
 }