Tcl Source Code

The result of the following script is the empty string:

proc main {} {
    set data [binary format a* hello]
    puts $data
    puts $data[set data {}]
}

main

Test and fix committed.

Just for the records, a variant of the original snippet without [puts]:

proc main {} {
    set data [binary format a* hello]
    return [expr {$data}][set data {}]
}
main

Fix isn't right yet:

% proc demo {} {
    set data [binary format a* hello]
    return [encoding convertto $data]$data
}
% demo
hellolr
%

Fixed in [f274e1f1baf02516].