in version 3.1.29 bug for PHP 7

[great-handsome]

i think it bug in PHP 7.
in dev-master
file sysplugins/smarty_internal_templatecompilerbase.php
line 735
return $this->smarty->registered_plugins[ Smarty::PLUGIN_COMPILER ][ $tag ][ 0 ][ 0 ]->$function[ 1 ]($args,

line 676
return $this->default_handler_plugins[ $plugin_type ][ $tag ][ 0 ][ 0 ]->$function[ 1 ]($new_args,

php.net/manual/en/migration70.incompatible.php

Expression $foo->$bar['baz']()
PHP 5 interpretation $foo->{$bar['baz']}()
PHP 7 interpretation ($foo->$bar)['baz']() 

[uwetews]

You are wrong as there is no variable class variable like $bar

[great-handsome]

I don't understand how is it will be work in PHP 7 without a changes.
Code for PHP 5:
line 735
return $this->smarty->registered_plugins[ Smarty::PLUGIN_COMPILER ][ $tag ][ 0 ][ 0 ]->$function[ 1 ]($args,
line 676
return $this->default_handler_plugins[ $plugin_type ][ $tag ][ 0 ][ 0 ]->$function[ 1 ]($new_args,

I think for PHP 7 needs code ( added { , } )
return $this->smarty->registered_plugins[ Smarty::PLUGIN_COMPILER ][ $tag ][ 0 ][ 0 ]->{$function[ 1 ]}($args,
line 676
return $this->default_handler_plugins[ $plugin_type ][ $tag ][ 0 ][ 0 ]->{$function[ 1 ]}($new_args,

[uwetews]

Sorry, yes you have been absolutely right.
The fix is in the master branch