Remove the constants that assume a base unit in favor of explicit
x_per_y constants.
nanosecond calendar timestamps now use i128 for the type. This affects
fs.File.Stat, std.time.nanoTimestamp, and fs.File.updateTimes.
calendar timestamps are now signed, because the value can be less than
the epoch (the user can set their computer time to whatever they wish).
implement std.os.clock_gettime for Windows when clock id is
CLOCK_CALENDAR.
* libc_installation.cpp is deleted.
src-self-hosted/libc_installation.zig is now used for both stage1 and
stage2 compilers.
* (breaking) move `std.fs.File.access` to `std.fs.Dir.access`. The API
now encourages use with an open directory handle.
* Add `std.os.faccessat` and related functions.
* Deprecate the "C" suffix naming convention for null-terminated
parameters. "C" should be used when it is related to libc. However
null-terminated parameters often have to do with the native system
ABI rather than libc. "Z" suffix is the new convention. For example,
`std.os.openC` is deprecated in favor of `std.os.openZ`.
* Add `std.mem.dupeZ` for using an allocator to copy memory and add a
null terminator.
* Remove dead struct field `std.ChildProcess.llnode`.
* Introduce `std.event.Batch`. This API allows expressing concurrency
without forcing code to be async. It requires no Allocator and does
not introduce any failure conditions. However it is not thread-safe.
* There is now an ongoing experiment to transition away from
`std.event.Group` in favor of `std.event.Batch`.
* `std.os.execvpeC` calls `getenvZ` rather than `getenv`. This is
slightly more efficient on most systems, and works around a
limitation of `getenv` lack of integration with libc.
* (breaking) `std.os.AccessError` gains `FileBusy`, `SymLinkLoop`, and
`ReadOnlyFileSystem`. Previously these error codes were all reported
as `PermissionDenied`.
* Add `std.Target.isDragonFlyBSD`.
* stage2: access to the windows_sdk functions is done with a manually
maintained .zig binding file instead of `@cImport`.
* Update src-self-hosted/libc_installation.zig with all the
improvements that stage1 has seen to src/libc_installation.cpp until
now. In addition, it now takes advantage of Batch so that evented I/O
mode takes advantage of concurrency, but it still works in blocking
I/O mode, which is how it is used in stage1.
