variable tab completion does not escape curly quotes, potentially others

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:

PowerShell/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs

Lines 4565 to 4566 in 981c990

    
           private static readonly char[] s_charactersRequiringQuotes = new char[] { 
        
               '-', '`', '&', '@', '\'', '"', '#', '{', '}', '(', ')', '$', ',', ';', '|', '<', '>', ' ', '.', '\\', '/', '\t', '^',

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.

Also, slightly related,

${test`{`}} = 'Hello World'

$t # press tab for completion until `{test{}}` appears

Expected

${test`{`}}

Actual

${test{}}

This will cause an error stating that you must use `{ instead of { in variable names.

This is actually further complicated, because the variables $$, $^, $! etc are all special. They should require braces, but the tokenizer explicitly allows them as special variables.

Never heard of $!. The regex above was set to handle the fact that the tokenizer accepts those special conditions.

I think I might have missed $? … EDIT: I corrected the above regex for the special condition of $?

Also adding that $?? fails to be completed correctly as ${??}, as I noticed ? was not in the constant list of characters in the code referenced.

Edit: $:?? is also acceptable.

Sample PowerShell filter code for testing:

filter variablenotate {
    if ($_ -match '^(?:[^$^\w?:]|[$^?].)|.(?:::|[^\w?:])') {
        "{$($_ -replace '[{}`]', '`$0')}"
    } else {
        $_
    }
}

Note that a more complete filter might escape all control characters, such that <TAB> (^I) would become `t and so on.

Edit: missed ` in the list of characters that need escaped in the -replace operation.

Edit: improved performance of the -match regex

Also adding that variables with backticks in their name will properly wrap with ${ } when completed but fail to escape the backtick in that notation.

I've also found that there are some issues around variables that contain : (I know there are some opinions there), but demonstrating a more complete escaper:

filter variableNotate {
    param(
        [string]$ScopeOrProviderPrefix = '' # specify either scope or provider prefix
    )
    # return a result object similar to the System.Management.Automation.CompletionResult class
    [pscustomobject]@{ 
        ListItemText   = $_
        CompletionText = "$($(
            if ($ScopeOrProviderPrefix -eq '') {
                # no scope/drive prefix, detect reasons to force a blank prefix
                if ($_.Contains([char]':') -or $_ -match '^\?[\w?:]+$') {
                    # force `:` prefix for names containing `:` or beginning with `?` but not needing `{}`
                    ":$_"
                } else {
                    #no prefixing needed
                    $_
                }
            } else {
                # assemble the prefixed completion
                "${ScopeOrProviderPrefix}:$_"
            }
        ).foreach{
            # detect if final completion requires `{}`
            if ($_ -match '^(?:[^$^\w?:]|[$^?].)|.(?:::|[^\w?:])') {
                # `{}` required, escape where needed
                "{$($_ -replace '[{}`]', '`$0')}"
            } else {
                # no wrapping or escaping needed
                $_
            }
        })"
    }
}

This filter now produces an output similar to the CompletionResult class.

Example usages: (uses aliases)

(dir env:*).name | variableNotate 'env'

(dir variable:*).name | variableNotate

Both above should demonstrate the correct escaped completion to use with the $ sigil.

(Partial Output from env:*)

ListItemText                    CompletionText
------------                    --------------
OS                              env:OS
CommonProgramFiles(x86)         {env:CommonProgramFiles(x86)}
HOMEPATH                        env:HOMEPATH
ProgramFiles(x86)               {env:ProgramFiles(x86)}
ProgramData                     env:ProgramData
TMP                             env:TMP

(Partial Output from variable:*)

ListItemText                CompletionText
------------                --------------
$                           $
^                           ^
?                           ?
*hello                      {*hello}
hello                       hello
@hello                      {@hello}
a                           a
`                           {``}
::                          {:::}
:                           ::
??                          :??

While writing this up, I also found that the *Hello variable doesn't complete correctly, * is also missing from the list of characters that require escape, but you can see this filter suggests the correct completion.

Edit: Revised filter a few times to optimize the regex, and better capture condition of variables starting with '?', Reference the ?? variable in the sample output.

I have an intention to post a PR regarding at least parts of this issue, implementing the escapers already found in the CodeGeneration class, and we'll see how far I can go from there.

implementing GenerateVariableCompletionText

I was able to implement a C# version of my PowerShell filter,

https://github.com/msftrncs/PowerShell/blob/0af1d06de68391d04f77c3efd3db58a8bd23a036/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs#L4804-L4843

Where does this best belong?

improve variable name competion results

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

This issue has been marked as "No Activity" as there has been no activity for 6 months. It has been closed for housekeeping purposes.

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variable tab completion does not escape curly quotes, potentially others #10006

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	private static readonly char[] s_charactersRequiringQuotes = new char[] {
	'-', '`', '&', '@', '\'', '"', '#', '{', '}', '(', ')', '$', ',', ';', '\|', '<', '>', ' ', '.', '\\', '/', '\t', '^',

variable tab completion does not escape curly quotes, potentially others #10006

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Expected behavior

Actual behavior

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msftrncs commented on Jun 26, 2019

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vexx32 commented on Jun 26, 2019

msftrncs commented on Jun 26, 2019

msftrncs commented on Jun 26, 2019

msftrncs commented on Jun 26, 2019

msftrncs commented on Jun 26, 2019

msftrncs commented on Jul 1, 2019

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msftrncs commented on Jul 22, 2019

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