Modernize our readline API a tad.

Prefer to call "rl_filename_completion_function" and
"rl_completion_matches", rather than using the names without the rl_
prefix.  This matches Readline's documentation, and makes our code
a little clearer about which names are external.  On platforms that
only have the un-prefixed names (just some very ancient versions of
libedit, AFAICT), reverse the direction of the compatibility macro
definitions to match.

Also, remove our extern declaration of "filename_completion_function";
whatever libedit versions may have failed to declare that are surely
dead and buried.

Discussion: https://postgr.es/m/23608.1576248145@sss.pgh.pa.us

Author: tglsfdc

src/bin/psql/tab-complete.c

@@ -50,15 +50,17 @@
 #include "settings.h"
 #include "stringutils.h"
 
-#ifdef HAVE_RL_FILENAME_COMPLETION_FUNCTION
-#define filename_completion_function rl_filename_completion_function
-#else
-/* missing in some header files */
-extern char *filename_completion_function();
+/*
+ * Ancient versions of libedit provide filename_completion_function()
+ * instead of rl_filename_completion_function().  Likewise for
+ * [rl_]completion_matches().
+ */
+#ifndef HAVE_RL_FILENAME_COMPLETION_FUNCTION
+#define rl_filename_completion_function filename_completion_function
 #endif
 
-#ifdef HAVE_RL_COMPLETION_MATCHES
-#define completion_matches rl_completion_matches
+#ifndef HAVE_RL_COMPLETION_MATCHES
+#define rl_completion_matches completion_matches
 #endif
 
 /* word break characters */
@@ -182,27 +184,27 @@ static bool completion_case_sensitive;	/* completion is case sensitive */
 #define COMPLETE_WITH_QUERY(query) \
 do { \
 	completion_charp = query; \
-	matches = completion_matches(text, complete_from_query); \
+	matches = rl_completion_matches(text, complete_from_query); \
 } while (0)
 
 #define COMPLETE_WITH_VERSIONED_QUERY(query) \
 do { \
 	completion_vquery = query; \
-	matches = completion_matches(text, complete_from_versioned_query); \
+	matches = rl_completion_matches(text, complete_from_versioned_query); \
 } while (0)
 
 #define COMPLETE_WITH_SCHEMA_QUERY(query, addon) \
 do { \
 	completion_squery = &(query); \
 	completion_charp = addon; \
-	matches = completion_matches(text, complete_from_schema_query); \
+	matches = rl_completion_matches(text, complete_from_schema_query); \
 } while (0)
 
 #define COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(query, addon) \
 do { \
 	completion_squery = query; \
 	completion_vquery = addon; \
-	matches = completion_matches(text, complete_from_versioned_schema_query); \
+	matches = rl_completion_matches(text, complete_from_versioned_schema_query); \
 } while (0)
 
 /*
@@ -213,14 +215,14 @@ do { \
 do { \
 	completion_case_sensitive = (cs); \
 	completion_charp = (con); \
-	matches = completion_matches(text, complete_from_const); \
+	matches = rl_completion_matches(text, complete_from_const); \
 } while (0)
 
 #define COMPLETE_WITH_LIST_INT(cs, list) \
 do { \
 	completion_case_sensitive = (cs); \
 	completion_charpp = (list); \
-	matches = completion_matches(text, complete_from_list); \
+	matches = rl_completion_matches(text, complete_from_list); \
 } while (0)
 
 #define COMPLETE_WITH_LIST(list) COMPLETE_WITH_LIST_INT(false, list)
@@ -260,7 +262,7 @@ do { \
 		completion_info_charp = _completion_table; \
 		completion_info_charp2 = _completion_schema; \
 	} \
-	matches = completion_matches(text, complete_from_query); \
+	matches = rl_completion_matches(text, complete_from_query); \
 } while (0)
 
 #define COMPLETE_WITH_ENUM_VALUE(type) \
@@ -285,7 +287,7 @@ do { \
 		completion_info_charp = _completion_type; \
 		completion_info_charp2 = _completion_schema; \
 	} \
-	matches = completion_matches(text, complete_from_query); \
+	matches = rl_completion_matches(text, complete_from_query); \
 } while (0)
 
 #define COMPLETE_WITH_FUNCTION_ARG(function) \
@@ -310,7 +312,7 @@ do { \
 		completion_info_charp = _completion_function; \
 		completion_info_charp2 = _completion_schema; \
 	} \
-	matches = completion_matches(text, complete_from_query); \
+	matches = rl_completion_matches(text, complete_from_query); \
 } while (0)
 
 /*
@@ -1335,7 +1337,7 @@ ends_with(const char *s, char c)
  * According to readline spec this gets passed the text entered so far and its
  * start and end positions in the readline buffer. The return value is some
  * partially obscure list format that can be generated by readline's
- * completion_matches() function, so we don't have to worry about it.
+ * rl_completion_matches() function, so we don't have to worry about it.
  */
 static char **
 psql_completion(const char *text, int start, int end)
@@ -1488,7 +1490,7 @@ psql_completion(const char *text, int start, int end)
 /* CREATE */
 	/* complete with something you can create */
 	else if (TailMatches("CREATE"))
-		matches = completion_matches(text, create_command_generator);
+		matches = rl_completion_matches(text, create_command_generator);
 
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
@@ -1498,7 +1500,7 @@ psql_completion(const char *text, int start, int end)
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
 	else if (Matches("DROP"))
-		matches = completion_matches(text, drop_command_generator);
+		matches = rl_completion_matches(text, drop_command_generator);
 
 /* ALTER */
 
@@ -1509,7 +1511,7 @@ psql_completion(const char *text, int start, int end)
 
 	/* ALTER something */
 	else if (Matches("ALTER"))
-		matches = completion_matches(text, alter_command_generator);
+		matches = rl_completion_matches(text, alter_command_generator);
 	/* ALTER TABLE,INDEX,MATERIALIZED VIEW ALL IN TABLESPACE xxx */
 	else if (TailMatches("ALL", "IN", "TABLESPACE", MatchAny))
 		COMPLETE_WITH("SET TABLESPACE", "OWNED BY");
@@ -2261,7 +2263,7 @@ psql_completion(const char *text, int start, int end)
 			 Matches("COPY", "BINARY", MatchAny, "FROM|TO"))
 	{
 		completion_charp = "";
-		matches = completion_matches(text, complete_from_files);
+		matches = rl_completion_matches(text, complete_from_files);
 	}
 
 	/* Handle COPY [BINARY] <sth> FROM|TO filename */
@@ -2483,7 +2485,11 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches("CREATE", "RULE", MatchAny, "AS") ||
 			 Matches("CREATE", "OR", "REPLACE", "RULE", MatchAny, "AS"))
 		COMPLETE_WITH("ON");
-	/* Complete "CREATE [ OR REPLACE ] RULE <sth> AS ON" with SELECT|UPDATE|INSERT|DELETE */
+
+	/*
+	 * Complete "CREATE [ OR REPLACE ] RULE <sth> AS ON" with
+	 * SELECT|UPDATE|INSERT|DELETE
+	 */
 	else if (Matches("CREATE", "RULE", MatchAny, "AS", "ON") ||
 			 Matches("CREATE", "OR", "REPLACE", "RULE", MatchAny, "AS", "ON"))
 		COMPLETE_WITH("SELECT", "UPDATE", "INSERT", "DELETE");
@@ -3708,9 +3714,9 @@ psql_completion(const char *text, int start, int end)
 	else if (TailMatchesCS("\\h|\\help", MatchAny))
 	{
 		if (TailMatches("DROP"))
-			matches = completion_matches(text, drop_command_generator);
+			matches = rl_completion_matches(text, drop_command_generator);
 		else if (TailMatches("ALTER"))
-			matches = completion_matches(text, alter_command_generator);
+			matches = rl_completion_matches(text, alter_command_generator);
 
 		/*
 		 * CREATE is recognized by tail match elsewhere, so doesn't need to be
@@ -3809,7 +3815,7 @@ psql_completion(const char *text, int start, int end)
 						   "\\s|\\w|\\write|\\lo_import"))
 	{
 		completion_charp = "\\";
-		matches = completion_matches(text, complete_from_files);
+		matches = rl_completion_matches(text, complete_from_files);
 	}
 
 	/*
@@ -4395,7 +4401,7 @@ complete_from_files(const char *text, int state)
 		}
 	}
 
-	unquoted_match = filename_completion_function(unquoted_text, state);
+	unquoted_match = rl_filename_completion_function(unquoted_text, state);
 	if (unquoted_match)
 	{
 		/*