Remove redundant null pointer checks before pg_free()

These are especially useless because the whole point of pg_free() was
to do that very check before calling free().

pg_free() could be removed altogether, but I'm keeping it here to keep
the API consistent.

Discussion: https://www.postgresql.org/message-id/flat/dac5d2d0-98f5-94d9-8e69-46da2413593d%40enterprisedb.com

src/bin/pg_basebackup/walmethods.c

@@ -500,7 +500,6 @@ dir_close(Walfile f, WalCloseMethod method)
 
 	pg_free(df->pathname);
 	pg_free(df->fullpath);
-	if (df->temp_suffix)
 	pg_free(df->temp_suffix);
 	pg_free(df);
 

src/bin/pg_upgrade/parallel.c

@@ -130,13 +130,10 @@ parallel_exec_prog(const char *log_file, const char *opt_log_file,
 		new_arg = exec_thread_args[parallel_jobs - 1];
 
 		/* Can only pass one pointer into the function, so use a struct */
-		if (new_arg->log_file)
 		pg_free(new_arg->log_file);
 		new_arg->log_file = pg_strdup(log_file);
-		if (new_arg->opt_log_file)
 		pg_free(new_arg->opt_log_file);
 		new_arg->opt_log_file = opt_log_file ? pg_strdup(opt_log_file) : NULL;
-		if (new_arg->cmd)
 		pg_free(new_arg->cmd);
 		new_arg->cmd = pg_strdup(cmd);
 
@@ -243,13 +240,10 @@ parallel_transfer_all_new_dbs(DbInfoArr *old_db_arr, DbInfoArr *new_db_arr,
 		/* Can only pass one pointer into the function, so use a struct */
 		new_arg->old_db_arr = old_db_arr;
 		new_arg->new_db_arr = new_db_arr;
-		if (new_arg->old_pgdata)
 		pg_free(new_arg->old_pgdata);
 		new_arg->old_pgdata = pg_strdup(old_pgdata);
-		if (new_arg->new_pgdata)
 		pg_free(new_arg->new_pgdata);
 		new_arg->new_pgdata = pg_strdup(new_pgdata);
-		if (new_arg->old_tablespace)
 		pg_free(new_arg->old_tablespace);
 		new_arg->old_tablespace = old_tablespace ? pg_strdup(old_tablespace) : NULL;
 

src/bin/pgbench/pgbench.c

@@ -5475,11 +5475,9 @@ static void
 free_command(Command *command)
 {
 	termPQExpBuffer(&command->lines);
-	if (command->first_line)
 	pg_free(command->first_line);
 	for (int i = 0; i < command->argc; i++)
 		pg_free(command->argv[i]);
-	if (command->varprefix)
 	pg_free(command->varprefix);
 
 	/*
@@ -6637,7 +6635,6 @@ main(int argc, char **argv)
 				is_init_mode = true;
 				break;
 			case 'I':
-				if (initialize_steps)
 				pg_free(initialize_steps);
 				initialize_steps = pg_strdup(optarg);
 				checkInitSteps(initialize_steps);

src/bin/psql/command.c

@@ -3492,7 +3492,6 @@ do_connect(enum trivalue reuse_previous_specification,
 	}							/* end retry loop */
 
 	/* Release locally allocated data, whether we succeeded or not */
-	if (password)
 	pg_free(password);
 	if (cinfo)
 		PQconninfoFree(cinfo);

src/bin/psql/variables.c

@@ -255,7 +255,6 @@ SetVariable(VariableSpace space, const char *name, const char *value)
 
 			if (confirmed)
 			{
-				if (current->value)
 				pg_free(current->value);
 				current->value = new_value;
 
@@ -272,7 +271,7 @@ SetVariable(VariableSpace space, const char *name, const char *value)
 					free(current);
 				}
 			}
-			else if (new_value)
+			else
 				pg_free(new_value); /* current->value is left unchanged */
 
 			return confirmed;