PowerShell does not correctly capture stdout from a windows app when redirecting to a file #28113

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues.
• Refer to the FAQ.
• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

#25875

See example code at https://github.com/rhubarb-geek-nz/pipe-dream

t1 is a console app
t2 and t3 are window apps

All three write to stdout.

With PowerShell piping output from t1.exe to a file works.

With PowerShell redirecting output from t2.exe and t3.exe to a file creates an empty file.

The working assumption is that PowerShell creates a pipe for stdout and does the writing to the file itself rather than handing the file handle to the child.

Because the app is not a console app it does not wait for the process to finish.

However, because it should be reading from a pipe and writing to a file, when the process terminates is irrelevant, it should wait for the end of file on the pipe.

Using

.\t2.exe | Out-String -Stream

Does work as expected and shows that the stdout can be processed from a windows application.

Expected behavior

That redirecting output from a windows app will write all stdout content to a file.

Actual behavior

Redirection output from a windows app to a file creates an empty file

Error details

File contains zero bytes

Environment data

Name                           Value
----                           -----
PSVersion                      7.6.6
PSEdition                      Core
GitCommitId                    7.6.6
OS                             Microsoft Windows 10.0.26200
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.4
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

No response