introduce operating system version ranges as part of the target

 * re-introduce `std.build.Target` which is distinct from `std.Target`.
   `std.build.Target` wraps `std.Target` so that it can be annotated as
   "the native target" or an explicitly specified target.
 * `std.Target.Os` is moved to `std.Target.Os.Tag`. The former is now a
   struct which has the tag as well as version range information.
 * `std.elf` gains some more ELF header constants.
 * `std.Target.parse` gains the ability to parse operating system
   version ranges as well as glibc version.
 * Added `std.Target.isGnuLibC()`.
 * self-hosted dynamic linker detection and glibc version detection.
   This also adds the improved logic using `/usr/bin/env` rather than
   invoking the system C compiler to find the dynamic linker when zig
   is statically linked. Related: #2084
   Note: this `/usr/bin/env` code is work-in-progress.
 * `-target-glibc` CLI option is removed in favor of the new `-target`
   syntax. Example: `-target x86_64-linux-gnu.2.27`

closes #1907

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/std/event/future.zig b/lib/std/event/future.zig
index 492582da75..51a63e90ee 100644
--- a/lib/std/event/future.zig
+++ b/lib/std/event/future.zig
@@ -86,7 +86,7 @@ test "std.event.Future" {
     // https://github.com/ziglang/zig/issues/1908
     if (builtin.single_threaded) return error.SkipZigTest;
     // https://github.com/ziglang/zig/issues/3251
-    if (builtin.os == .freebsd) return error.SkipZigTest;
+    if (builtin.os.tag == .freebsd) return error.SkipZigTest;
     // TODO provide a way to run tests in evented I/O mode
     if (!std.io.is_async) return error.SkipZigTest;