C comment:  clarify why psql's help/exit/quit must alone
Document why no indentation and why no non-whitespace postfix is
supported.
Backpatch-through: master
@@ -237,7 +237,13 @@ MainLoop(FILE *source)
bool found_exit_or_quit = false;
bool found_q = false;
- /* Search for the words we recognize; must be first word */
+ /*
+ * The assistance words, help/exit/quit, must have no
+ * whitespace before them, and only whitespace after, with an
+ * optional semicolon. This prevents indented use of these
+ * words, perhaps as identifiers, from invoking the assistance
+ * behavior.
+ */
if (pg_strncasecmp(first_word, "help", 4) == 0)
{
rest_of_line = first_word + 4;
@@ -249,7 +255,6 @@ MainLoop(FILE *source)
rest_of_line = first_word + 4;
found_exit_or_quit = true;
}
-
else if (strncmp(first_word, "\\q", 2) == 0)
{
rest_of_line = first_word + 2;
