Add tab completion of EXECUTE FUNCTION for CREATE TRIGGER in psql

The change to accept EXECUTE FUNCTION as well as EXECUTE PROCEDURE in
CREATE TRIGGER (added by 0a63f996) forgot to tell psql's tab completion
system about this.  In passing, add tab completion of EXECUTE
FUNCTION/PROCEDURE after a complete WHEN ( … ) clause.

This change is version-aware, with FUNCTION being selected automatically
instead of PROCEDURE depending on the backend version, PROCEDURE being
an historical grammar kept for compatibility and considered as
deprecated in v11.

Author: Dagfinn Ilmari Mannsåker
Reviewed-by: Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/d8jmur4q4yc.fsf@dalvik.ping.uio.no

src/bin/psql/tab-complete.c

@@ -2465,7 +2465,8 @@ psql_completion(const char *text, int start, int end)
 
 	/*
 	 * complete CREATE TRIGGER <name> BEFORE,AFTER event ON with a list of
-	 * tables
+	 * tables.  EXECUTE FUNCTION is the recommended grammar instead of EXECUTE
+	 * PROCEDURE in version 11 and upwards.
 	 */
 	else if (TailMatches("CREATE", "TRIGGER", MatchAny, "BEFORE|AFTER", MatchAny, "ON"))
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
@@ -2473,11 +2474,22 @@ psql_completion(const char *text, int start, int end)
 	else if (TailMatches("CREATE", "TRIGGER", MatchAny, "INSTEAD", "OF", MatchAny, "ON"))
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_views, NULL);
 	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("ON", MatchAny))
-		COMPLETE_WITH("NOT DEFERRABLE", "DEFERRABLE", "INITIALLY",
-					  "REFERENCING", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("NOT DEFERRABLE", "DEFERRABLE", "INITIALLY",
+						  "REFERENCING", "FOR", "WHEN (", "EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("NOT DEFERRABLE", "DEFERRABLE", "INITIALLY",
+						  "REFERENCING", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	}
 	else if (HeadMatches("CREATE", "TRIGGER") &&
 			 (TailMatches("DEFERRABLE") || TailMatches("INITIALLY", "IMMEDIATE|DEFERRED")))
-		COMPLETE_WITH("REFERENCING", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("REFERENCING", "FOR", "WHEN (", "EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("REFERENCING", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	}
 	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("REFERENCING"))
 		COMPLETE_WITH("OLD TABLE", "NEW TABLE");
 	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("OLD|NEW", "TABLE"))
@@ -2485,17 +2497,32 @@ psql_completion(const char *text, int start, int end)
 	else if (HeadMatches("CREATE", "TRIGGER") &&
 			 (TailMatches("REFERENCING", "OLD", "TABLE", "AS", MatchAny) ||
 			  TailMatches("REFERENCING", "OLD", "TABLE", MatchAny)))
-		COMPLETE_WITH("NEW TABLE", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("NEW TABLE", "FOR", "WHEN (", "EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("NEW TABLE", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	}
 	else if (HeadMatches("CREATE", "TRIGGER") &&
 			 (TailMatches("REFERENCING", "NEW", "TABLE", "AS", MatchAny) ||
 			  TailMatches("REFERENCING", "NEW", "TABLE", MatchAny)))
-		COMPLETE_WITH("OLD TABLE", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("OLD TABLE", "FOR", "WHEN (", "EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("OLD TABLE", "FOR", "WHEN (", "EXECUTE PROCEDURE");
+	}
 	else if (HeadMatches("CREATE", "TRIGGER") &&
 			 (TailMatches("REFERENCING", "OLD|NEW", "TABLE", "AS", MatchAny, "OLD|NEW", "TABLE", "AS", MatchAny) ||
 			  TailMatches("REFERENCING", "OLD|NEW", "TABLE", MatchAny, "OLD|NEW", "TABLE", "AS", MatchAny) ||
 			  TailMatches("REFERENCING", "OLD|NEW", "TABLE", "AS", MatchAny, "OLD|NEW", "TABLE", MatchAny) ||
 			  TailMatches("REFERENCING", "OLD|NEW", "TABLE", MatchAny, "OLD|NEW", "TABLE", MatchAny)))
-		COMPLETE_WITH("FOR", "WHEN (", "EXECUTE PROCEDURE");
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("FOR", "WHEN (", "EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("FOR", "WHEN (", "EXECUTE PROCEDURE");
+	}
 	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("FOR"))
 		COMPLETE_WITH("EACH", "ROW", "STATEMENT");
 	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("FOR", "EACH"))
@@ -2503,11 +2530,29 @@ psql_completion(const char *text, int start, int end)
 	else if (HeadMatches("CREATE", "TRIGGER") &&
 			 (TailMatches("FOR", "EACH", "ROW|STATEMENT") ||
 			  TailMatches("FOR", "ROW|STATEMENT")))
-		COMPLETE_WITH("WHEN (", "EXECUTE PROCEDURE");
-	/* complete CREATE TRIGGER ... EXECUTE with PROCEDURE */
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("WHEN (", "EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("WHEN (", "EXECUTE PROCEDURE");
+	}
+	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("WHEN", "(*)"))
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("EXECUTE FUNCTION");
+		else
+			COMPLETE_WITH("EXECUTE PROCEDURE");
+	}
+	/* complete CREATE TRIGGER ... EXECUTE with PROCEDURE|FUNCTION */
 	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("EXECUTE"))
-		COMPLETE_WITH("PROCEDURE");
-	else if (HeadMatches("CREATE", "TRIGGER") && TailMatches("EXECUTE", "PROCEDURE"))
+	{
+		if (pset.sversion >= 110000)
+			COMPLETE_WITH("FUNCTION");
+		else
+			COMPLETE_WITH("PROCEDURE");
+	}
+	else if (HeadMatches("CREATE", "TRIGGER") &&
+			 TailMatches("EXECUTE", "FUNCTION|PROCEDURE"))
 		COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(Query_for_list_of_functions, NULL);
 
 /* CREATE ROLE,USER,GROUP <name> */