René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"variable tab completion does not escape curly quotes, potentially others","articleBody":"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 `${ }` notation.\r\n\r\n# Steps to reproduce\r\n\r\n```PowerShell\r\n${test`u{2018}var} = 'Hello World'\r\n\r\n$t # press tab for completion until `test‘var` appears\r\n```\r\n\r\n# Expected behavior\r\n\r\n```PowerShell\r\n${test‘var}\r\n\r\n```\r\n\r\n# Actual behavior\r\n\r\n```PowerShell\r\n$test‘var\r\n```\r\n\r\nI believe this is part of the issue:\r\nhttps://github.com/PowerShell/PowerShell/blob/981c990d747ae97f56a6c7474e5d2ef04bf237c5/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs#L4565-L4566\r\n\r\n\r\nI think this is inadequate to catch the conditions that require when the `${ }` 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 `${ }` is required.  Examples:\r\n\r\n`$`  false\r\n`$$` true\r\n`^` false\r\n`^^` true\r\n`?` false\r\n`??` true\r\n`_?` false\r\n`::` false\r\n`a::` true\r\n`test‘var` true\r\n\r\n# Environment data\r\n\r\nThis particular example was captured with 6.2.0 on Win 10 Pro 18922 (Insiders)\r\n\r\n__Edit: improved performance of the regex example.__\r\n","author":{"url":"https://github.com/msftrncs","@type":"Person","name":"msftrncs"},"datePublished":"2019-06-26T03:22:32.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":14},"url":"https://github.com/10006/PowerShell/issues/10006"}