Variables in Invoke-Expression arguments do not get counted as used.

[VARider]

Issue Type: Bug

When setting variables that are later used in Invoke-Expression commands, VS Code flags the variables as never used, even if they appear in the Invoke-Expression command.

1. Set a variable
2. Use the variable in an Invoke-Expression cmdlet.
3. Note that VS Code flags a warning that the command is assigned but not used.

Extension version: 2020.6.0
VS Code version: Code 1.51.1 (e5a624b788d92b8d34d1392e4c4d9789406efe8f, 2020-11-10T23:34:32.027Z)
OS version: Windows_NT x64 10.0.19042

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-7800X CPU @ 3.50GHz (12 x 3504)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: disabled_off opengl: enabled_on protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	63.69GB (52.26GB free)
Process Argv	--crash-reporter-id c1d64596-d05d-4a27-95a4-1f9c4a13a4af
Screen Reader	no
VM	0%

[VARider]

This code recreates the issue in the current public release version of VS Code

$PATHWEB = "C:\Windows\WEB\Wallpaper\Windows"
$USERACCOUNT = "System"
$PERMISSION = ":(OI)(CI)F" #(OI) Object Inherit; (CI) Container Inherit; (F) Full Access 
Invoke-Expression -Command ('ICACLS $PATHWEB /GRANT *S-1-1-0:F /T "${$USERACCOUNT}${$PERMISSION}"')

[SeeminglyScience]

Invoke-Expression can't really be statically analyzed accurately. That's one of the many downsides.

Side note, ${$USERACCOUNT} actually references a variable named $USERACCOUNT, not one named USERACCOUNT. You probably want "$USERACCOUNT$PERMISSION" or "${USERACCOUNT}${PERMISSION}".

Also you don't need Invoke-Expression there. You can do this instead:

$PATHWEB = "C:\Windows\WEB\Wallpaper\Windows"
$USERACCOUNT = "System"
$PERMISSION = "(OI)(CI)F" #(OI) Object Inherit; (CI) Container Inherit; (F) Full Access

ICACLS $PATHWEB /GRANT "${USERACCOUNT}:${PERMISSION}" /T

[VARider]

Ah ok. I am fairly new to all of this, so I am still learning. Thanks for the tip, I appreciate it.

[rjmholt]

Invoke-Expression can't really be statically analyzed accurately. That's one of the many downsides.

Yes, you should avoid Invoke-Expression wherever possible. We've been trying to collect use-cases where it's unavoidable but there don't seem to be many.

Because Invoke-Expression can assemble arbitrary strings at runtime before executing them, it's impossible to statically analyse. For example, you could make a web request that resolves a string that you then send to Invoke-Expression — there's no way to know before that web request is made whether $PATHWEB is going to be referenced by the executed string.

[VARider]

Awesome, thanks for the reply. I will close the issue since it is a known effect of the command. Thank You.