Failed to parse expression for $[

[gullevek]

Code example

foobar=$[$bar+$foo]

Says $[ has error, but this is valid bash syntax

on commandline (macos or linux)
$> bar=1;
$> foo=2;
$> foobar=$[$bar+$foo];
$> echo $foobar;
3

[skovhus]

Thanks for reporting. This is probably a limitation in the underlying gramma (https://github.com/tree-sitter/tree-sitter-bash).

This might be as $[] is deprecated in favor of $().

The manpage for bash v3.2.48 says:

[...] The format for arithmetic expansion is:

     $((expression))
The old format $[expression] is deprecated and will be removed in upcoming versions of bash.

So $[...] is the old syntax that should not be used anymore.