TZ env var doesn't work on Windows

[jkellyinsf]

• Version: 13.7.0 (also repro'd on 13.6.0)
• Platform: Windows 10 64 bit
• Subsystem: putil.cpp

I wrote this modest test file date.js that shows how the TZ env var is set and what time zone dates are using.

console.log(`node platform ${process.platform}, version ${process.version}`)
console.log(`process.env.TZ = ${process.env.TZ}`)
console.log(`default date ${new Date().toString()}, offset = ${new Date().getTimezoneOffset()}`)

My machine is in Pacific Time. When I override the TZ to UTC and run this script through the linux build of node (on Ubuntu under WSL), I get the UTC dates I expect:

$ TZ=UTC node date.js  
node platform linux, version v13.7.0                                                    
process.env.TZ = UTC                                                                    
default date Thu Jan 23 2020 14:54:15 GMT+0000 (Coordinated Universal Time), offset = 0 

When I run it with the Windows build, process.env.TZ claims to be in UTC, but dates still come out in Pacific Time.

# set TZ=UTC && node date.js
node platform win32, version v13.7.0                                                  
process.env.TZ = UTC                                                                  
default date Thu Jan 23 2020 06:54:30 GMT-0800 (Pacific Standard Time), offset = 480  

[addaleax]

/cc @nodejs/intl

[bnoordhuis]

I'm fairly sure #4230 (comment) is still the current state of things. That means TZ is ignored on Windows.

You can change the timezone with tzutil but that's a system-wide change, of course.

[sxa]

Unless there was something to actively set that on Windows, we're talking about a UNIX-specific variable so I would agree with @bnoordhuis - there's no reason why it would generally be interpreted by processes on Windows. If it was to be processed on non-UNIX based platforms, there would likely need to be a handler within Node.js itself to interpret all of the values in there to map all of the potential values of TZ to something meaningful - I haven't checked the code but I assume Node is currently calling into the OS to do the time zone translation.

[bnoordhuis]

I'll close this out as (not-)working-as-expected.