Calling the CLI from the outside with an empty command string (-c '') crashes PowerShell

From within PowerShell, running pwsh -c '' (pwsh -Command '') provides a helpful error message (followed by the CLI syntax):

Cannot process the command because of a missing parameter. A command must follow -Command.

By contrast, when pwsh is called from the outside, it crashes.

Steps to reproduce

Run from either cmd.exe or bash:

pwsh -c ""

Expected behavior

The following should print to stderr and a nonzero exit code should be reported, analogous to what happens when calling from PowerShell.

Cannot process the command because of a missing parameter. A command must follow -Command.

(CLI syntax diagram)

Actual behavior

The pwsh process crashes as follows:

Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'value')
   at System.String.IndexOf(String value, Int32 startIndex, Int32 count, StringComparison comparisonType)
   at System.String.IndexOf(String value, StringComparison comparisonType)
   at Microsoft.PowerShell.CommandLineParameterParser.MatchSwitch(String switchKey, String match, String smallestUnambiguousMatch)
   at Microsoft.PowerShell.CommandLineParameterParser.EarlyParse(String[] args)
   at Microsoft.PowerShell.UnmanagedPSEntry.Start(String consoleFilePath, String[] args, Int32 argc)
   at Microsoft.PowerShell.ManagedPSEntry.Main(String[] args)

Environment data

PowerShell Core 7.0.0-preview.4

[mklement0]

Agreed, @iSazonov.

On further reflection, I think I was wrong about the expected behavior in the OP:

Since an argument is passed to -c in this case, the syntax requirements are met, so we shouldn’t treat this the same as neglecting to pass an argument to -c.

After the "" are stripped by PowerShell’s CLI, a verbatim empty string remains (as opposed to a string literal representing the empty string). This is effectively the absence of any statement.

As a no-op, it is by definition successful, and the exit should be 0. This is consistent with how POSIX-compatible shells handle this case.

Since the current preview already exhibits this behavior, I think we can close this issue.

Note that the only reason it behaves differently when called from PowerShell is the broken handling of quoted arguments as described in #1995, which causes empty-string literals not to be passed at all, so that pwsh -c "" is unexpectedly the same as pwsh -c

[iSazonov]

@chuanjiao10 I think it is one issue.