REPL does not work in 6.0.0 release on Windows

[compnerd]

Description

No response

Reproduction

swift repl

Expected behavior

The REPL should launch

Environment

6.0.0-RELEASE

Additional information

No response

[compnerd]

CC: @al45tair

Turns out that this is a more serious consequence of #70005. We are also apparently scrubbing Path which in turns prevents the LoadLibraryW to fail when loading swiftCore in the sacrificial process. This can obviously be worked around by doing something like:

lldb --repl -x -S \lldb.init

Where \lldb.init contains:

settings set target.env-vars Path=S:\b\101\bin;S:\b\x64\cmark-gfm-0.29.0.gfm.13

[compnerd]

This is a regression as this worked at least in 20240523 on main.

[compnerd]

CC: @adrian-prantl

[adrian-prantl]

@compnerd I'm happy to review patches & provide guidance, but I don't think I have time to investigate this myself.

[compnerd]

@adrian-prantl swiftlang/llvm-project#9334 addresses this - the underlying issue is that we are clearing out the environment

[adrian-prantl]

Who is "we"? Where does it happen?

[compnerd]

In this context, it is LLDB. When the sacrificial inferior is created, it is done so without an initial environment. There are some rather important environment variables such as Path, UserProfile, TEMP, etc that need to be preserved for the tools to function. Retaining the full environment resolves the issue.