VSCode PowerShell syntax highlighting 'messed up' by changing file under VSCode

[charliearcuri]

20210315 1615856510-81b75b36-ddce-47dd-b292-72c53676f7601615855631823.zip

Issue Description

I am experiencing a problem with syntax highlighting when a .ps1 changes underneath VSCode.
Similarly, some changes cause PSScriptAnalyzer issues (e.g. "missing }" warnings that I could not make sense of)

Repro Steps

1. open VSCode - open output folder of my VS2019 project
2. open SDF-UefiFlash.ps1 using VSCode's Explorer
3. observe syntax highlighting (it is correct at this point)
4. close SDF-UefiFlash.ps1 in VSCode but keep the folder open
5. while keeping VSCode open, open VS2019 and open the solution that contains SDF-UefiFlash.ps1 in addition to a .NET class library used by the .ps1 script
6. In VS2019, make a change to SDF-UefiFlash.ps1 - this file being modified here is checked into git. The change I made was to add a .PARAMETER definition to the synopsis at the top of the file.
7. rebuild all in VS2019 - this copies the newly changed version of SDF-UefiFlash.ps1 to the output folder that VSCode has open
8. re-open SDF-UefiFlash.ps1 in VSCode

Expected Behaviour

The syntax highlighting works when I open a .ps1 in VSCode even if I have used VS2019 to update the file and published it to the folder VSCode has opened by 'rebuilding all' in VS2019.

Actual Behaviour

If I "rebuild all" in VS2019 while VSCode has the output folder open, when I open the .ps1 (which is copied to the output folder by the VS2019 rebuild all), the syntax highlighting is "messed up" - presumably because VSCode has some information about the syntax highlighting cached.

Attached Logs

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Environment Information

Visual Studio Code

Name	Version
Operating System	Windows_NT x64 10.0.19042
VSCode	1.54.3
PowerShell Extension Version	2021.2.2

PowerShell Information

Name	Value
PSVersion	7.1.3
PSEdition	Core
GitCommitId	7.1.3
OS	Microsoft Windows 10.0.19042
Platform	Win32NT
PSCompatibleVersions	1.0 2.0 3.0 4.0 5.0 5.1.10032.0 6.0.0 6.1.0 6.2.0 7.0.0 7.1.3
PSRemotingProtocolVersion	2.3
SerializationVersion	1.1.0.1
WSManStackVersion	3.0

Visual Studio Code Extensions

Visual Studio Code Extensions(Click to Expand)

Extension	Author	Version
cpptools	ms-vscode	1.2.2
jupyter	ms-toolsai	2021.3.619093157
powershell	ms-vscode	2021.2.2
python	ms-python	2021.2.636928669

[SydneyhSmith]

Thanks @charliearcuri this issue is related to our handling of external file change notifications--we will need to investigate what this work would entail after PowerShell/PowerShellEditorServices#1295 improves our thread handling

[ninmonkey]

Does it occur when semantic is disabled?

settings.json

"[powershell]": {
    "editor.semanticHighlighting.enabled": false
}