Fix psql's tab-completion of enum label values.

Since enum labels have to be single-quoted, this part of the
tab completion machinery got side-swiped by commit cd69ec6.
A side-effect of that commit is that (at least with some versions
of Readline) the text string passed for completion will omit the
leading quote mark of the enum label literal.  Libedit still acts
the same as before, though, so adapt COMPLETE_WITH_ENUM_VALUE so
that it can cope with either convention.

Also, when we fail to find any valid completion, set
rl_completion_suppress_quote = 1.  Otherwise readline will
go ahead and append a closing quote, which is unwanted.

Per report from Peter Eisentraut.  Back-patch to v13 where
cd69ec6 came in.

Discussion: https://postgr.es/m/8ca82d89-ec3d-8b28-8291-500efaf23b25@enterprisedb.com

src/bin/psql/t/010_tab_completion.pl

@@ -42,7 +42,8 @@
 $node->safe_psql('postgres',
 	    "CREATE TABLE tab1 (f1 int, f2 text);\n"
 	  . "CREATE TABLE mytab123 (f1 int, f2 text);\n"
-	  . "CREATE TABLE mytab246 (f1 int, f2 text);\n");
+	  . "CREATE TABLE mytab246 (f1 int, f2 text);\n"
+	  . "CREATE TYPE enum1 AS ENUM ('foo', 'bar', 'baz');\n");
 
 # Developers would not appreciate this test adding a bunch of junk to
 # their ~/.psql_history, so be sure to redirect history into a temp file.
@@ -223,6 +224,16 @@ sub clear_line
 
 clear_line();
 
+# check enum label completion
+# some versions of readline/libedit require two tabs here, some only need one
+# also, some versions will offer quotes, some will not
+check_completion(
+	"ALTER TYPE enum1 RENAME VALUE 'ba\t\t",
+	qr|'?bar'? +'?baz'?|,
+	"offer multiple enum choices");
+
+clear_line();
+
 # send psql an explicit \q to shut it down, else pty won't close properly
 $timer->start(5);
 $in .= "\\q\n";

src/bin/psql/tab-complete.c

@@ -278,25 +278,40 @@ do { \
 	matches = rl_completion_matches(text, complete_from_query); \
 } while (0)
 
+/*
+ * libedit will typically include the literal's leading single quote in
+ * "text", while readline will not.  Adapt our offered strings to fit.
+ * But include a quote if there's not one just before "text", to get the
+ * user off to the right start.
+ */
 #define COMPLETE_WITH_ENUM_VALUE(type) \
 do { \
 	char   *_completion_schema; \
 	char   *_completion_type; \
+	bool	use_quotes; \
 \
 	_completion_schema = strtokx(type, " \t\n\r", ".", "\"", 0, \
 								 false, false, pset.encoding); \
 	(void) strtokx(NULL, " \t\n\r", ".", "\"", 0, \
 				   false, false, pset.encoding); \
 	_completion_type = strtokx(NULL, " \t\n\r", ".", "\"", 0, \
-							   false, false, pset.encoding);  \
-	if (_completion_type == NULL)\
+							   false, false, pset.encoding); \
+	use_quotes = (text[0] == '\'' || \
+				  start == 0 || rl_line_buffer[start - 1] != '\''); \
+	if (_completion_type == NULL) \
 	{ \
-		completion_charp = Query_for_list_of_enum_values; \
+		if (use_quotes) \
+			completion_charp = Query_for_list_of_enum_values_quoted; \
+		else \
+			completion_charp = Query_for_list_of_enum_values_unquoted; \
 		completion_info_charp = type; \
 	} \
 	else \
 	{ \
-		completion_charp = Query_for_list_of_enum_values_with_schema; \
+		if (use_quotes) \
+			completion_charp = Query_for_list_of_enum_values_with_schema_quoted; \
+		else \
+			completion_charp = Query_for_list_of_enum_values_with_schema_unquoted; \
 		completion_info_charp = _completion_type; \
 		completion_info_charp2 = _completion_schema; \
 	} \
@@ -678,7 +693,7 @@ static const SchemaQuery Query_for_list_of_collations = {
 "   AND (pg_catalog.quote_ident(nspname)='%s' "\
 "        OR '\"' || nspname || '\"' ='%s') "
 
-#define Query_for_list_of_enum_values \
+#define Query_for_list_of_enum_values_quoted \
 "SELECT pg_catalog.quote_literal(enumlabel) "\
 "  FROM pg_catalog.pg_enum e, pg_catalog.pg_type t "\
 " WHERE t.oid = e.enumtypid "\
@@ -687,7 +702,16 @@ static const SchemaQuery Query_for_list_of_collations = {
 "        OR '\"' || typname || '\"'='%s') "\
 "   AND pg_catalog.pg_type_is_visible(t.oid)"
 
-#define Query_for_list_of_enum_values_with_schema \
+#define Query_for_list_of_enum_values_unquoted \
+"SELECT enumlabel "\
+"  FROM pg_catalog.pg_enum e, pg_catalog.pg_type t "\
+" WHERE t.oid = e.enumtypid "\
+"   AND substring(enumlabel,1,%d)='%s' "\
+"   AND (pg_catalog.quote_ident(typname)='%s' "\
+"        OR '\"' || typname || '\"'='%s') "\
+"   AND pg_catalog.pg_type_is_visible(t.oid)"
+
+#define Query_for_list_of_enum_values_with_schema_quoted \
 "SELECT pg_catalog.quote_literal(enumlabel) "\
 "  FROM pg_catalog.pg_enum e, pg_catalog.pg_type t, pg_catalog.pg_namespace n "\
 " WHERE t.oid = e.enumtypid "\
@@ -698,6 +722,17 @@ static const SchemaQuery Query_for_list_of_collations = {
 "   AND (pg_catalog.quote_ident(nspname)='%s' "\
 "        OR '\"' || nspname || '\"' ='%s') "
 
+#define Query_for_list_of_enum_values_with_schema_unquoted \
+"SELECT enumlabel "\
+"  FROM pg_catalog.pg_enum e, pg_catalog.pg_type t, pg_catalog.pg_namespace n "\
+" WHERE t.oid = e.enumtypid "\
+"   AND n.oid = t.typnamespace "\
+"   AND substring(enumlabel,1,%d)='%s' "\
+"   AND (pg_catalog.quote_ident(typname)='%s' "\
+"        OR '\"' || typname || '\"'='%s') "\
+"   AND (pg_catalog.quote_ident(nspname)='%s' "\
+"        OR '\"' || nspname || '\"' ='%s') "
+
 #define Query_for_list_of_template_databases \
 "SELECT pg_catalog.quote_ident(d.datname) "\
 "  FROM pg_catalog.pg_database d "\
@@ -4192,8 +4227,12 @@ psql_completion(const char *text, int start, int end)
 	if (matches == NULL)
 	{
 		COMPLETE_WITH_CONST(true, "");
+		/* Also, prevent Readline from appending stuff to the non-match */
 #ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
 		rl_completion_append_character = '\0';
+#endif
+#ifdef HAVE_RL_COMPLETION_SUPPRESS_QUOTE
+		rl_completion_suppress_quote = 1;
 #endif
 	}