get current time: Time.now, Time.utc_now

[bcardiff]

The following snippets work.

puts Time.now
puts Time.utc_now

simulate TZ using $ TZ="America/New_York" wine ./foo.exe

Note: this does not handle daylight savings.

[bcardiff]

This didn't make travis happy :-( hold a bit please.

[bcardiff]

Travis is happy again. Ready to go if you think the path taken is good.

I think it would be great if you can enable travis on this fork and enable builds for PR. I hope other will join forces :-)

[lbguilherme]

Travis has been enabled! 🎉

I've made some review comments, but I'm not sure how it notifies you (after the review system changed). Did you see them?

[bcardiff]

I see no review comments. After writing them yo need to click on the "review changes" button in the top right to send them all.

[lbguilherme]

This could be a single date_time : UInt64 to avoid calculation later

[bcardiff]

this way it matches docs. UInt64 would work since it will be guaranteed to be aligned at it is used as out in the method call.

In the docs it is warned the following thing:

Do not cast a pointer to a FILETIME structure to either a ULARGE_INTEGER* or __int64* value because it can cause alignment faults on 64-bit Windows.

If struct FileTime to UInt64 there will be no problem since it is the cast is in the other way, but it is misleading.

What do you prefer?

[lbguilherme]

It would even be safe to declare it as GetSystemTimeAsFileTime(time : UInt64*). The problem would be if the struct were declared as UInt32, allocated as such and then accessed by a Uint64* if it were on a architecture were accessing misaligned memory caused a crash (This causes problems on ARM, and Window can run on ARM). But it is pretty safe to declare those pairs of high/low DWords as a single UInt64 as long as the struct is allocated by you and not returned from a function.

Are you a lot against doing it?

[bcardiff]

I think I prefer safe for know, yes. Rust does the same in https://github.com/rust-lang/rust/blob/b1363a73ede57ae595f3a1be2bb75d308ba4f7f6/src/libstd/sys/windows/time.rs

Changing to alias FileTime = UInt64 can be done later I think.
The div and % are much heavier that the bitwise operations.

We can ask for a third vote :-)

[lbguilherme]

Well... let's do as documented. This can be changed later if proven to be better. Merging.

[lbguilherme]

(opinated) Better use snake_case for argument names here, even though it contradicts the original name from MSDN docs. I would also give simpler names like tz_info or time. What do you think?

[bcardiff]

sure

[lbguilherme]

Docs says it returns TIME_ZONE_ID_INVALID in case of error. Add a check here:

if LibWindows.get_time_zone_information(out tz) == LibWindows::TIME_ZONE_ID_INVALID
  raise WinError.new("GetTimeZoneInformation")
end

The possible return values are:

TIME_ZONE_ID_INVALID = -1
TIME_ZONE_ID_UNKNOWN = 0
TIME_ZONE_ID_STANDARD = 1
TIME_ZONE_ID_DAYLIGHT = 2

[lbguilherme]

GetSystemTimeAsFileTime returns Void

[lbguilherme]

Check the return value here:

if LibWindows.get_time_zone_information(out tz) == TIME_ZONE_ID_UNKNOWN
  raise WinError.new("GetTimeZoneInformation")
end

The constants are:

internal const int TIME_ZONE_ID_INVALID = -1;
internal const int TIME_ZONE_ID_UNKNOWN = 0;
internal const int TIME_ZONE_ID_STANDARD = 1;
internal const int TIME_ZONE_ID_DAYLIGHT = 2;

[bcardiff]

Unknown should not raise.

TIME_ZONE_ID_UNKNOWN: Daylight saving time is not used in the current time zone, because there are no transition dates or automatic adjustment for daylight saving time is disabled.

Invalid yes.

If the function fails for other reasons, such as an out of memory error, it returns TIME_ZONE_ID_INVALID. To get extended error information, call GetLastError.