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Fix positional parameter re-binding when parameter appears in multiple sets #27089

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1e95d50
Fix positional parameter re-binding when parameter appears in multipl…
powercode Mar 24, 2026
be40680
test: add tab completion regression tests for issue 2212
powercode Mar 24, 2026
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8 changes: 8 additions & 0 deletions src/System.Management.Automation/engine/CommandCompletion/PseudoParameterBinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1823,6 +1823,14 @@ private bool BindPseudoPositionalParameterInSet(
uint localParameterSetFlag = 0;
foreach (PositionalCommandParameter parameter in nextPositionalParameters.Values)
{
// Skip parameters that were already bound at a previous position.
// Mirrors the same guard in BindPositionalParametersInSet().
// See https://github.com/PowerShell/PowerShell/issues/2212
if (_boundParameters.ContainsKey(parameter.Parameter.Parameter.Name))
{
continue;
}

foreach (ParameterSetSpecificMetadata parameterSetData in parameter.ParameterSetData)
{
// Skip it if it's not in the specified parameter set
Expand Down
10 changes: 10 additions & 0 deletions src/System.Management.Automation/engine/ParameterBinderController.cs
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Expand Up @@ -929,6 +929,16 @@ out ParameterBindingException bindingException

foreach (PositionalCommandParameter parameter in nextPositionalParameters.Values)
{
// Skip parameters that were already bound at a previous position.
// A parameter can appear at multiple positions across different parameter sets
// (e.g., Position=0 in set 'Two' and Position=1 in set 'One'). Once bound,
// it must not be re-bound (and overwritten) when the loop reaches the other position.
// See https://github.com/PowerShell/PowerShell/issues/2212
if (BoundParameters.ContainsKey(parameter.Parameter.Parameter.Name))
{
continue;
}

foreach (ParameterSetSpecificMetadata parameterSetData in parameter.ParameterSetData)
{
// if the parameter is not in the specified parameter set, don't consider it
Expand Down
171 changes: 162 additions & 9 deletions test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
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Expand Up @@ -51,7 +51,7 @@ Describe "TabCompletion" -Tags CI {
New-ModuleManifest -Path "$($NewDir.FullName)\$ModuleName.psd1" -RootModule "$ModuleName.psm1" -FunctionsToExport "MyTestFunction" -ModuleVersion $NewDir.Name
}

$env:PSModulePath += [System.IO.Path]::PathSeparator + $tempDir
$env:PSModulePath += [System.IO.Path]::PathSeparator + $tempDir
$Res = TabExpansion2 -inputScript MyTestFunction
$Res.CompletionMatches.Count | Should -Be 2
$SortedMatches = $Res.CompletionMatches.CompletionText | Sort-Object
Expand Down Expand Up @@ -82,7 +82,7 @@ Describe "TabCompletion" -Tags CI {
New-ModuleManifest -Path "$($NewDir.FullName)\$ModuleName.psd1" -RootModule "$ModuleName.psm1" -FunctionsToExport "MyTestFunction" -ModuleVersion $NewDir.Name
}

$env:PSModulePath += [System.IO.Path]::PathSeparator + $tempDir
$env:PSModulePath += [System.IO.Path]::PathSeparator + $tempDir
$Res = TabExpansion2 -inputScript 'Import-Module -Name TestModule'
$Res.CompletionMatches.Count | Should -Be 1
$Res.CompletionMatches[0].CompletionText | Should -Be TestModule1
Expand Down Expand Up @@ -165,21 +165,21 @@ Describe "TabCompletion" -Tags CI {
$res = TabExpansion2 -inputScript 'param($PS = $P'
$res.CompletionMatches.Count | Should -BeGreaterThan 0
}

It 'Should complete variable with description and value <Value>' -TestCases @(
@{ Value = 1; Expected = '[int]$VariableWithDescription - Variable description' }
@{ Value = 'string'; Expected = '[string]$VariableWithDescription - Variable description' }
@{ Value = $null; Expected = 'VariableWithDescription - Variable description' }
) {
param ($Value, $Expected)

New-Variable -Name VariableWithDescription -Value $Value -Description 'Variable description' -Force
$res = TabExpansion2 -inputScript '$VariableWithDescription'
$res.CompletionMatches.Count | Should -Be 1
$res.CompletionMatches[0].CompletionText | Should -BeExactly '$VariableWithDescription'
$res.CompletionMatches[0].ToolTip | Should -BeExactly $Expected
}

It 'Should complete environment variable' {
try {
$env:PWSH_TEST_1 = 'value 1'
Expand Down Expand Up @@ -226,7 +226,7 @@ Describe "TabCompletion" -Tags CI {
@{ Value = $null; Expected = 'VariableWithDescription - Variable description' }
) {
param ($Value, $Expected)

New-Variable -Name VariableWithDescription -Value $Value -Description 'Variable description' -Force
$res = TabExpansion2 -inputScript '$local:VariableWithDescription'
$res.CompletionMatches.Count | Should -Be 1
Expand Down Expand Up @@ -1191,7 +1191,7 @@ param([ValidatePattern(
[Parameter(ParameterSetName = 'SetWithoutHelp')]
[string]
$ParamWithHelp,

[Parameter(ParameterSetName = 'SetWithHelp')]
[switch]
$ParamWithoutHelp
Expand Down Expand Up @@ -1733,7 +1733,7 @@ param([ValidatePattern(

$commaSeparators = "',' ', '"
$semiColonSeparators = "';' '; '"

$squareBracketFormatString = "'[{0}]'"
$curlyBraceFormatString = "'{0:N2}'"
}
Expand Down Expand Up @@ -2097,6 +2097,159 @@ Verb-Noun -Param1 Hello ^
$res.CompletionMatches[0].CompletionText | Should -Be "Attributes"
}

Context 'Positional parameter completion with multi-set parameters (issue #2212)' {
BeforeAll {
function Test-Func2212 {
[CmdletBinding(DefaultParameterSetName = 'Two')]
param(
[Parameter(ParameterSetName = 'One', Position = 1)]
[Parameter(ParameterSetName = 'Two', Position = 0)]
[string]$First,

[Parameter(ParameterSetName = 'Two', Position = 1)]
[string]$Second,

[Parameter(ParameterSetName = 'One', Position = 0)]
[string]$OnlyOne
)
}

function Test-FuncSamePos {
[CmdletBinding(DefaultParameterSetName = 'Alpha')]
param(
[Parameter(ParameterSetName = 'Alpha', Position = 0)]
[string]$AlphaValue,

[Parameter(ParameterSetName = 'Beta', Position = 0)]
[string]$BetaValue
)
}

function Test-FuncMultiSetNamed {
[CmdletBinding(DefaultParameterSetName = 'A')]
param(
[Parameter(ParameterSetName = 'A', Position = 0)]
[Parameter(ParameterSetName = 'B', Position = 1)]
[string]$Alpha,

[Parameter(ParameterSetName = 'A')]
[string]$OnlyA,

[Parameter(ParameterSetName = 'B', Position = 0)]
[string]$OnlyB
)
}

function Test-Func2212Arg {
[CmdletBinding()]
param(
[Parameter(Position = 0)]
[string]$Param1,

[Parameter(Position = 1)]
[System.Management.Automation.ActionPreference]$Param2
)
}

function Test-Func2212FakeBound {
[CmdletBinding(DefaultParameterSetName = 'Two')]
param(
[Parameter(ParameterSetName = 'One', Position = 1)]
[Parameter(ParameterSetName = 'Two', Position = 0)]
[string]$First,

[Parameter(ParameterSetName = 'Two', Position = 1)]
[string]$Second,

[Parameter(ParameterSetName = 'One', Position = 0)]
[string]$OnlyOne,

[ArgumentCompleter({
param($commandName, $parameterName, $wordToComplete, $commandAst, $fakeBoundParameters)

$hasFirst = [string]$fakeBoundParameters.Contains('First')
$hasSecond = [string]$fakeBoundParameters.Contains('Second')
$hasOnlyOne = [string]$fakeBoundParameters.Contains('OnlyOne')

$firstValue = if ($fakeBoundParameters.Contains('First')) { [string]$fakeBoundParameters['First'] } else { '<none>' }
$secondValue = if ($fakeBoundParameters.Contains('Second')) { [string]$fakeBoundParameters['Second'] } else { '<none>' }
$onlyOneValue = if ($fakeBoundParameters.Contains('OnlyOne')) { [string]$fakeBoundParameters['OnlyOne'] } else { '<none>' }

$results = @(
"HasFirst:$hasFirst",
"HasSecond:$hasSecond",
"HasOnlyOne:$hasOnlyOne",
"FirstValue:$firstValue",
"SecondValue:$secondValue",
"OnlyOneValue:$onlyOneValue"
)

foreach ($item in $results)
{
[System.Management.Automation.CompletionResult]::new($item, $item, 'ParameterValue', $item)
}
})]
[string]$Probe
)
}
}

it 'Should not offer already-bound positional parameter for completion (issue #2212)' {
$ScriptInput = 'Test-Func2212 Hello -'
$res = TabExpansion2 -inputScript $ScriptInput -cursorColumn $ScriptInput.Length
$completionTexts = $res.CompletionMatches.CompletionText
$completionTexts | Should -Contain '-Second'
$completionTexts | Should -Not -Contain '-First'
}

it 'Should not offer re-bound parameter after two positional args (issue #2212)' {
$ScriptInput = 'Test-Func2212 Hello World -'
$res = TabExpansion2 -inputScript $ScriptInput -cursorColumn $ScriptInput.Length
$completionTexts = $res.CompletionMatches.CompletionText
$completionTexts | Should -Not -Contain '-First'
$completionTexts | Should -Not -Contain '-Second'
$completionTexts | Should -Contain '-Verbose'
}

it 'Should offer correct parameters when named param narrows set with multi-position parameter' {
$ScriptInput = 'Test-FuncMultiSetNamed -OnlyA val -'
$res = TabExpansion2 -inputScript $ScriptInput -cursorColumn $ScriptInput.Length
$completionTexts = $res.CompletionMatches.CompletionText
$completionTexts | Should -Contain '-Alpha'
$completionTexts | Should -Not -Contain '-OnlyB'
}

it 'Should complete argument for correct positional parameter with multi-set positions' {
$ScriptInput = 'Test-Func2212Arg Hello '
$res = TabExpansion2 -inputScript $ScriptInput -cursorColumn $ScriptInput.Length
$completionTexts = $res.CompletionMatches.CompletionText
$completionTexts | Should -Contain 'Break'
$completionTexts | Should -Contain 'Continue'
}

it 'Should handle same numeric position in different sets during completion' {
$ScriptInput = 'Test-FuncSamePos val1 -'
$res = TabExpansion2 -inputScript $ScriptInput -cursorColumn $ScriptInput.Length
$completionTexts = $res.CompletionMatches.CompletionText
$completionTexts | Should -Not -Contain '-AlphaValue'
$completionTexts | Should -Not -Contain '-BetaValue'
$completionTexts | Should -Contain '-Verbose'
}

it 'Should pass correct fakeBoundParameters for multi-set positional binding (issue #2212)' {
$ScriptInput = 'Test-Func2212FakeBound Hello World -Probe '
$res = TabExpansion2 -inputScript $ScriptInput -cursorColumn $ScriptInput.Length
$completionTexts = $res.CompletionMatches.CompletionText

$completionTexts | Should -Contain 'HasFirst:True'
$completionTexts | Should -Contain 'HasSecond:True'
$completionTexts | Should -Contain 'HasOnlyOne:False'
$completionTexts | Should -Contain 'FirstValue:Hello'
$completionTexts | Should -Contain 'SecondValue:World'
$completionTexts | Should -Contain 'OnlyOneValue:<none>'
}
}

it 'Should complete base class members of types without type definition AST' {
$res = TabExpansion2 -inputScript @'
class InheritedClassTest : System.Attribute
Expand Down Expand Up @@ -2408,7 +2561,7 @@ param ($Param1)
$null = New-Item -Path $TestFile
$res = TabExpansion2 -ast $scriptAst -tokens $tokens -positionOfCursor $cursorPosition
Pop-Location

$ExpectedPath = Join-Path -Path '.\' -ChildPath $ExpectedFileName
$res.CompletionMatches.CompletionText | Where-Object {$_ -Like "*$ExpectedFileName"} | Should -Be $ExpectedPath
}
Expand Down
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