Similar to #9881, while attempting to tab complete a variable reference, at least curly quotes (I've also determined en-dash/em-dash too) do not cause an escape to the ${ } notation.

Steps to reproduce

${test`u{2018}var} = 'Hello World'

$t # press tab for completion until `test‘var` appears

Expected behavior

${test‘var}

Actual behavior

$test‘var

I believe this is part of the issue:

I think this is inadequate to catch the conditions that require when the ${ } notation is needed, but the above constant appears to be used for more than just that. The list of characters that require the ${ } notation is much larger and more complicated. If regex could be used, the following might be more accurate for when to require the ${ } : ^(?:[^$^\w?:]|[$^?].)|.(?:::|[^\w?:]) This would return a MATCH when ${ } is required. Examples:

$ false
$$ true
^ false
^^ true
? false
?? true
_? false
:: false
a:: true
test‘var true

Environment data

This particular example was captured with 6.2.0 on Win 10 Pro 18922 (Insiders)

Edit: improved performance of the regex example.