Refactor hba_authname

The previous implementation (from 9afffcb8) had an unnecessary check
on the boundaries of the enum which trigtered compile warnings. To clean
it up, move the pre-existing static assert to a central location and
call that.

Reported-By: Erik Rijkers
Reviewed-By: Michael Paquier
Discussion: https://postgr.es/m/1056399262.13159.1617793249020@webmailclassic.xs4all.nl

src/backend/libpq/auth.c

@@ -379,7 +379,7 @@ set_authn_id(Port *port, const char *id)
 		ereport(LOG,
 				errmsg("connection authenticated: identity=\"%s\" method=%s "
 					   "(%s:%d)",
-					   port->authn_id, hba_authname(port), HbaFileName,
+					   port->authn_id, hba_authname(port->hba->auth_method), HbaFileName,
 					   port->hba->linenumber));
 	}
 }

src/backend/libpq/hba.c

@@ -2607,14 +2607,8 @@ fill_hba_line(Tuplestorestate *tuple_store, TupleDesc tupdesc,
 		else
 			nulls[index++] = true;
 
-		/*
-		 * Make sure UserAuthName[] tracks additions to the UserAuth enum
-		 */
-		StaticAssertStmt(lengthof(UserAuthName) == USER_AUTH_LAST + 1,
-						 "UserAuthName[] must match the UserAuth enum");
-
 		/* auth_method */
-		values[index++] = CStringGetTextDatum(UserAuthName[hba->auth_method]);
+		values[index++] = CStringGetTextDatum(hba_authname(hba->auth_method));
 
 		/* options */
 		options = gethba_options(hba);
@@ -3150,18 +3144,13 @@ hba_getauthmethod(hbaPort *port)
  * should not be freed.
  */
 const char *
-hba_authname(hbaPort *port)
+hba_authname(UserAuth auth_method)
 {
-	UserAuth	auth_method;
-
-	Assert(port->hba);
-	auth_method = port->hba->auth_method;
-
-	if (auth_method < 0 || USER_AUTH_LAST < auth_method)
-	{
-		/* Should never happen. */
-		elog(FATAL, "port has out-of-bounds UserAuth: %d", auth_method);
-	}
+	/*
+	 * Make sure UserAuthName[] tracks additions to the UserAuth enum
+	 */
+	StaticAssertStmt(lengthof(UserAuthName) == USER_AUTH_LAST + 1,
+					 "UserAuthName[] must match the UserAuth enum");
 
 	return UserAuthName[auth_method];
 }

src/include/libpq/hba.h

@@ -137,7 +137,7 @@ typedef struct Port hbaPort;
 
 extern bool load_hba(void);
 extern bool load_ident(void);
-extern const char *hba_authname(hbaPort *port);
+extern const char *hba_authname(UserAuth auth_method);
 extern void hba_getauthmethod(hbaPort *port);
 extern int	check_usermap(const char *usermap_name,
 						  const char *pg_role, const char *auth_user,