Compile Variables

Compile variables are accessible by importing the "builtin" package, which the compiler makes available to every Zig source file. It contains compile-time constants such as the current target, endianness, and release mode.

  1. const builtin = @import("builtin");
  2. const separator = if (builtin.os.tag == builtin.Os.windows) '\\' else '/';

Example of what is imported with @import("builtin"):

  1. const std = @import("std");
  2. /// Zig version. When writing code that supports multiple versions of Zig, prefer
  3. /// feature detection (i.e. with `@hasDecl` or `@hasField`) over version checks.
  4. pub const zig_version = std.SemanticVersion.parse("0.8.1") catch unreachable;
  5. /// Temporary until self-hosted is feature complete.
  6. pub const zig_is_stage2 = true;
  7. /// Temporary until self-hosted supports the `cpu.arch` value.
  8. pub const stage2_arch: std.Target.Cpu.Arch = .x86_64;
  10. pub const output_mode = std.builtin.OutputMode.Obj;
  11. pub const link_mode = std.builtin.LinkMode.Static;
  12. pub const is_test = false;
  13. pub const single_threaded = false;
  14. pub const abi = std.Target.Abi.gnu;
  15. pub const cpu: std.Target.Cpu = .{
  16.     .arch = .x86_64,
  17.     .model = &std.Target.x86.cpu.skylake,
  18.     .features = std.Target.x86.featureSet(&[_]std.Target.x86.Feature{
  19.         .@"64bit",
  20.         .adx,
  21.         .aes,
  22.         .avx,
  23.         .avx2,
  24.         .bmi,
  25.         .bmi2,
  26.         .clflushopt,
  27.         .cmov,
  28.         .cx16,
  29.         .cx8,
  30.         .ermsb,
  31.         .f16c,
  32.         .false_deps_popcnt,
  33.         .fast_15bytenop,
  34.         .fast_gather,
  35.         .fast_scalar_fsqrt,
  36.         .fast_shld_rotate,
  37.         .fast_variable_shuffle,
  38.         .fast_vector_fsqrt,
  39.         .fma,
  40.         .fsgsbase,
  41.         .fxsr,
  42.         .idivq_to_divl,
  43.         .invpcid,
  44.         .lzcnt,
  45.         .macrofusion,
  46.         .mmx,
  47.         .movbe,
  48.         .nopl,
  49.         .pclmul,
  50.         .popcnt,
  51.         .prfchw,
  52.         .rdrnd,
  53.         .rdseed,
  54.         .sahf,
  55.         .sgx,
  56.         .slow_3ops_lea,
  57.         .sse,
  58.         .sse2,
  59.         .sse3,
  60.         .sse4_1,
  61.         .sse4_2,
  62.         .ssse3,
  63.         .vzeroupper,
  64.         .x87,
  65.         .xsave,
  66.         .xsavec,
  67.         .xsaveopt,
  68.         .xsaves,
  69.     }),
  70. };
  71. pub const os = std.Target.Os{
  72.     .tag = .linux,
  73.     .version_range = .{ .linux = .{
  74.         .range = .{
  75.             .min = .{
  76.                 .major = 5,
  77.                 .minor = 4,
  78.                 .patch = 122,
  79.             },
  80.             .max = .{
  81.                 .major = 5,
  82.                 .minor = 4,
  83.                 .patch = 122,
  84.             },
  85.         },
  86.         .glibc = .{
  87.             .major = 2,
  88.             .minor = 31,
  89.             .patch = 0,
  90.         },
  91.     }},
  92. };
  93. pub const target = std.Target{
  94.     .cpu = cpu,
  95.     .os = os,
  96.     .abi = abi,
  97. };
  98. pub const object_format = std.Target.ObjectFormat.elf;
  99. pub const mode = std.builtin.Mode.Debug;
  100. pub const link_libc = false;
  101. pub const link_libcpp = false;
  102. pub const have_error_return_tracing = true;
  103. pub const valgrind_support = true;
  104. pub const position_independent_code = false;
  105. pub const position_independent_executable = false;
  106. pub const strip_debug_info = false;
  107. pub const code_model = std.builtin.CodeModel.default;

See also: