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, 2 insertions, 2 deletions

diff --git a/lib/std/builtin.zig b/lib/std/builtin.zig
index 1bb8fd85ae..3204ce905e 100644
--- a/lib/std/builtin.zig
+++ b/lib/std/builtin.zig
@@ -411,7 +411,7 @@ pub const Version = struct {
         }
     };
 
-    pub fn order(lhs: Version, rhs: version) std.math.Order {
+    pub fn order(lhs: Version, rhs: Version) std.math.Order {
         if (lhs.major < rhs.major) return .lt;
         if (lhs.major > rhs.major) return .gt;
         if (lhs.minor < rhs.minor) return .lt;
@@ -504,7 +504,7 @@ pub fn default_panic(msg: []const u8, error_return_trace: ?*StackTrace) noreturn
         root.os.panic(msg, error_return_trace);
         unreachable;
     }
-    switch (os) {
+    switch (os.tag) {
         .freestanding => {
             while (true) {
                 @breakpoint();