0.17.0 Release Notes

Carmen the Allocgator

Download & Documentation

Zig is a general-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.

Zig development is funded via Zig Software Foundation, a 501(c)(3) non-profit organization. Please consider a recurring donation so that we can offer more billable hours to our core team members. This is the most straightforward way to accelerate the project along the Roadmap to 1.0. If you need donation receipts or are looking to migrate away from GitHub Sponsors, we recommend donating via Every.org.

This release features 5 months of work: changes from 206 different contributors, spread among 925 commits.

Originally predicted to be shorter, this release cycle ended up substantial, with the Build System reworked, including the introduction of the Build Server Protocol, and the ELF Linker enhanced to the point where we expect Incremental Compilation to work for everyone on x86_64-linux.

Table of Contents §

Target Support §

Zero the Ziguana

Zig supports a wide range of architectures and operating systems. The Support Table and Additional Platforms sections cover the targets that Zig can build programs for, while the zig-bootstrap README covers the targets that the Zig Compiler itself can be easily cross-compiled to run on.

Notable changes:

Tier System §

Zig's level of support for various targets is broadly categorized into four tiers with Tier 1 being the highest. The goal is for Tier 1 targets to have zero disabled tests - this will become a requirement for post-1.0.0 Zig releases.

Tier 1 §

Tier 2 §

Tier 3 §

Tier 4 §

Support Table §

In the following table, ✅ indicates full support, ❌ indicates no support, and ⚠️ indicates that there is partial support, e.g. only for some sub-targets, or with some notable known issues. ❔ indicates that the status is largely unknown, typically because the target is rarely exercised. Hover over other icons for details.

Targets marked with 🪦 are obsolescent; the Zig compiler and standard library maintain best-effort support for them, but that support is expected to be removed eventually.

Tier Target Code Gen. Linker Lang. Feat. Std. Lib. Stack Traces Fuzzer libc CI
1 x86_64-linux 🖥️⚡ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 aarch64-freebsd 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 aarch64[_be]-linux 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 aarch64-maccatalyst 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 aarch64-macos 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 aarch64[_be]-netbsd 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 aarch64-openbsd 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 aarch64-windows 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 arm-freebsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 arm[eb]-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 arm[eb]-netbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 arm-openbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 hexagon-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 loongarch32-linux 🖥🛠 ✅ ❔ ✅ ✅ ❌ ✅ ⚠️
2 loongarch64-linux 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 mips[el]-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 mips[el]-netbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 mips64[el]-linux 🖥️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 mips64[el]-openbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 powerpc-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 powerpc-netbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 powerpc-openbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 powerpc64[le]-freebsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 powerpc64[le]-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 powerpc64-openbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 riscv32-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 riscv32-netbsd 🖥️ ✅ ✅ ✅ ✅ ✅ ✅ ⚠️
2 riscv64-freebsd 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ⚠️
2 riscv64-linux 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 riscv64-netbsd 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ⚠️
2 riscv64-openbsd 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 s390x-linux 🖥️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 sparc64-linux 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 thumb[eb]-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 wasm32-wasi 🖥️🛠️ ✅ ✅ ✅ ⚠️ ❌ ✅ ✅
2 x86-linux 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 x86-netbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 x86-openbsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ⚠️
2 🪦 x86-windows 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 x86_64-freebsd 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 🪦 x86_64-maccatalyst 🖥️⚡ ✅ ✅ ✅ ✅ ✅ ✅ ⚠️
2 🪦 x86_64-macos 🖥️⚡ ✅ ✅ ✅ ✅ ✅ ✅ ⚠️
2 x86_64-netbsd 🖥️🛠️ ✅ ✅ ✅ ✅ ✅ ✅ ✅
2 x86_64-openbsd 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
2 x86_64-windows 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ✅ ✅
3 aarch64-haiku 🖥️🛠️ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 aarch64-ios 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 aarch64-serenity 🖥️🛠️ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 aarch64-tvos 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 aarch64-visionos 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 aarch64-watchos 🖥️🛠️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 arm-haiku 🖥️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 mips64[el]-netbsd 🖥️ ✅ ✅ ✅ ❌️ ✅ ❌️ ❌️
3 riscv64-haiku 🖥️🛠️ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 riscv64-serenity 🖥️🛠️ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 🪦 thumb-windows 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ❌️
3 wasm64-wasi 🖥️🛠️ ✅ ❔ ❌️ ⚠️ ❌ ❌️ ❌️
3 🪦 x86-freebsd 🖥️ ✅ ✅ ✅ ✅ ❌ ✅ ❌
3 x86-haiku 🖥️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 🪦 x86-illumos 🖥️ ✅ ✅ ✅ ✅ ❌ ❌️ ❌️
3 x86_64-dragonfly 🖥️🛠️ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 x86_64-haiku 🖥️⚡ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 x86_64-illumos 🖥️🛠️ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
3 x86_64-serenity 🖥️⚡ ✅ ✅ ✅ ✅ ❔ ❌️ ❌️
4 alpha-linux 📄 ❌️ ❔ ✅ ✅ ❌ ❌️ ❌️
4 alpha-netbsd 📄 ❌️ ❔ ✅ ✅ ❌ ❌️ ❌️
4 alpha-openbsd 📄 ❌️ ❔ ✅ ✅ ❌ ❌️ ❌️
4 arc[eb]-linux 📄 ❌️ ❔ ✅ ✅ ❌ ✅ ❌️
4 csky-linux 📄 ❌️ ❔ ✅ ✅ ❌ ✅ ❌️
4 hppa-linux 📄 ❌️ ❔ ❌️ ❌️ ❌ ❌️ ❌️
4 hppa-netbsd 📄 ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️
4 hppa-openbsd 📄 ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️
4 hppa64-linux 📄 ❌️ ❔ ❌️ ❌️ ❌ ❌️ ❌️
4 m68k-linux 🖥️ ❌️ ❔ ✅ ✅ ❌ ✅ ❌️
4 m68k-netbsd 🖥️ ❌️ ❔ ✅ ✅ ❌ ✅ ❌️
4 m88k-openbsd 📄 ❌️ ❔ ✅ ✅ ❌ ❌️ ❌️
4 microblaze[el]-linux 📄 ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️
4 or1k-linux 📄 ❌️ ❔ ✅ ✅ ❌ ❌️ ❌️
4 sh[eb]-linux 📄 ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️
4 sh[eb]-netbsd 📄 ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️
4 sh-openbsd 📄 ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️
4 sparc-linux 🖥️ ❌️ ❔ ✅ ✅ ❌ ✅ ❌️
4 sparc-netbsd 🖥️ ❌️ ❔ ✅ ❌️ ❌ ✅ ❌️
4 sparc64-netbsd 🖥️🛠️ ⚠️ ✅ ✅ ❌️ ✅ ✅ ❌️
4 sparc64-openbsd 🖥️🛠️ ⚠️ ✅ ✅ ❌️ ❌ ✅ ❌️
4 xtensa[eb]-linux 🖥️ ❌️ ❔ ✅ ❌️ ❌ ❌️ ❌️

OS Version Requirements §

The Zig standard library has minimum version requirements for some supported operating systems, which in turn affect the Zig compiler itself:

OS Version
Darwin 15.0+
DragonFly BSD 6.4+
FreeBSD 14.0+
Linux 5.10+
NetBSD 10.1+
OpenBSD 7.8+
Windows 10+

Additional Platforms §

Zig also has varying levels of support for these targets, for which the tier system does not quite apply:

Language Changes §

Language Stability Progress §

Since the release of Zig 0.16.0, a lot of progress has been made towards stabilizing the language. This is a key step in our roadmap, and a requirement before tagging Zig 1.0.

In particular, since the last release, we have discussed and made decisions on many language proposals—accepting around 25 and rejecting around 125. At the time of writing, 23 undecided language proposals remain open on the Codeberg issue tracker, and 61 undecided language proposals remain open on the legacy GitHub issue tracker. Therefore, this effort represents a significant step towards finalizing the language design (although some major decisions remain).

@bitCast changes §

Zig 0.17.0 changes the definition of the @bitCast builtin.

In many cases, the new behavior is equivalent to the old: in particular, casting between an integer type and another integer type is unaffected, as is casting between an integer type and a packed struct or packed union.

However, the semantics of @bitCast calls involving array or vector types have changed. Unfortunately, this change has the potential to break existing code without triggering a compile error.. Therefore, it may be useful when upgrading to audit any @bitCast uses which involve array or vector types.

The new definition of @bitCast is that it reinterprets the logical bit representation of a value as a different type. The following types are considered to have logical bit representations:

For integer and floating-point types, the logical bit representation starts with the least-significant bit and ends with the most-significant bit. For array and vector types, all elements' logical bit representations are concatenated in order starting with the first element.

In practice, this means that the new @bitCast definition largely aligns with the old behavior on little-endian targets. Unlike the old behavior, the new behavior is fully endian-agnostic, i.e. the operation behaves the same regardless of the target endian.

The new @bitCast definition disallows casts between some types which were previously allowed. In particular, casts involving extern struct or extern union types are no longer permitted. In most cases, code which was using such casts is aiming to reinterpret the value's in-memory representation (sometimes called "type punning")—to achieve this, use @ptrCast or an extern union.

bitcast_extern_struct.zig
const TwoBytes = extern struct {
    b0: u8,
    b1: u8,
};
test "type pun extern struct" {
    const bytes: TwoBytes = .{ .b0 = 0x12, .b1 = 0xAB };
    const int: u16 = @bitCast(bytes);
    switch (std.lang.Endian.native) {
        .little => try expectEqual(0xAB_12, int),
        .big => try expectEqual(0x12_AB, int),
    }
}
const std = @import("std");
const expectEqual = std.testing.expectEqual;
Shell
$ zig test bitcast_extern_struct.zig
/home/ci/.cache/act/4d2db5a0202099f4/hostexecutor/src/download/0.17.0/release-notes/bitcast_extern_struct.zig:7:31: error: cannot @bitCast from 'bitcast_extern_struct.TwoBytes'
    const int: u16 = @bitCast(bytes);
                              ^~~~~
/home/ci/.cache/act/4d2db5a0202099f4/hostexecutor/src/download/0.17.0/release-notes/bitcast_extern_struct.zig:1:25: note: struct declared here
const TwoBytes = extern struct {
                 ~~~~~~~^~~~~~

⬇️

ptrcast_extern_struct.zig
const TwoBytes = extern struct {
    b0: u8,
    b1: u8,
};
test "type pun extern struct" {
    const bytes: TwoBytes = .{ .b0 = 0x12, .b1 = 0xAB };
    const int_ptr: *align(1) const u16 = @ptrCast(&bytes);
    switch (std.lang.Endian.native) {
        .little => try expectEqual(0xAB_12, int_ptr.*),
        .big => try expectEqual(0x12_AB, int_ptr.*),
    }
}
const std = @import("std");
const expectEqual = std.testing.expectEqual;
Shell
$ zig test ptrcast_extern_struct.zig
1/1 ptrcast_extern_struct.test.type pun extern struct...OK
All 1 tests passed.

Formally Specified and Fuzzed Grammar §

Zig's formal grammar.peg and the actual language implementation did not agree in many places. Probably, the formal grammar has never actually 100% matched the actual handwritten tokenizer and parser.

This problem is now fixed and unblocks future grammar changes and language specification work.

At a high level, the approach was to write a tool that accepts Zig's grammar.peg as input and outputs a simple recursive descent parser. This generated parser is then used as an oracle for fuzz testing and the handwritten std.zig.Ast.parse() is compared against it. This approach ensures a single source of truth and allows for easy iteration as the grammar changes.

More details: #36094

C Translation Moving to External Package §

@cImport was deprecated in Zig 0.16.0 and is now removed. Furthermore, in this release std.Build.Step.TranslateC is deprecated in favor of an explicit package dependency on official ZSF translate-c package, which is the same implementation the build step provides, but offers more configuration options for the translated code, and has an independent release cadence from the main Zig toolchain.

Upgrade guide:

zig fetch --save git+https://codeberg.org/ziglang/translate-c
--- a/build.zig
+++ b/build.zig
@@ -1,16 +1,19 @@
 const std = @import("std");
+const Translator = @import("translate_c").Translator;
 
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
-    const translate_c = b.addTranslateC(.{
-        .root_source_file = b.path("src/c.h"),
+    const translate_c = b.dependency("translate_c", .{});
+
+    const translator: Translator = .init(translate_c, .{
+        .c_source_file = b.path("src/c.h"),
         .target = target,
         .optimize = optimize,
+ // additional options now available that go here:
+ // https://codeberg.org/ziglang/translate-c#options
     });
-    translate_c.linkSystemLibrary("glfw", .{});
-    translate_c.linkSystemLibrary("epoxy", .{});
+    translator.linkSystemLibrary("glfw3", .{});
+    translator.linkSystemLibrary("epoxy", .{});
 
     const exe = b.addExecutable(.{
         .name = "tetris",
@@ -21,7 +24,7 @@ pub fn build(b: *std.Build) void {
             .imports = &.{
                 .{
                     .name = "c",
-                    .module = translate_c.createModule(),
+                    .module = translator.mod,
                 },
             },
         }),

Added @backingInt and @fromBackingInt §

The @backingInt and @fromBackingInt builtins are new. These builtins replace the now-deprecated @intFromEnum and @enumFromInt builtins (#35966).

@backingInt works with all enums and with bitpacks with explicit backing integer types only. It also works with tagged unions, returning the backing integer of the active tag value. An undefined enum or bitpack yields an undefined backing integer.

@fromBackingInt infers its result type, which may be any enum or a bitpack with an explicit backing integer type. It takes a parameter of exactly that backing integer type. For enums, passing a backing integer that is either undefined or would yield an invalid tag value results in safety-checked Illegal Behavior. For bitpacks, passing an undefined backing integer yields an undefined bitpack.

@bitCast now also performs a safety check for invalid tag values if its destination type is an enum.

Also adds a std.meta.BackingInt function to get the result type of @backingInt.

Zig now requires empty enums to have noreturn as their backing integer because they are uninstantiable.

Upgrade example:

--- a/lib/std/Build.zig
+++ b/lib/std/Build.zig
@@ -145,7 +145,7 @@ pub const Graph = struct {
 
     pub fn addGeneratedFile(graph: *Graph, owner: *Step) Configuration.GeneratedFileIndex {
         graph.generated_files.append(graph.arena, owner) catch @panic("OOM");
-        return @enumFromInt(graph.generated_files.items.len - 1);
+        return @fromBackingInt(@intCast(graph.generated_files.items.len - 1));
     }
 
     pub fn dupeString(graph: *const Graph, bytes: []const u8) []const u8 {
@@ -2607,7 +2607,7 @@ pub const LazyPath = union(enum) {
             .src_path, .cwd_relative, .relative, .dependency => {},
             .generated => |gen| {
                 const graph = other_step.owner.graph;
-                const generated_owner_step = graph.generated_files.items[@intFromEnum(gen.index)];
+                const generated_owner_step = graph.generated_files.items[@backingInt(gen.index)];
                 other_step.dependOn(generated_owner_step);
             },
         }

zig fmt automatically performs this upgrade.

Added @SpirvType §

SPIR-V has a number of types, such as images and samplers, that have no equivalent in Zig's type system. Previously, the only way to refer to one of them was through inline assembly, which made it impossible to declare a texture or a storage buffer as an ordinary global variable. Zig 0.17.0 implements accepted proposal #35240, adding the @SpirvType builtin alongside the other type-creating builtins:

sample_code
@SpirvType(comptime options: std.lang.Type.Spirv) type

Using this builtin when not targeting SPIR-V is a compile error. The options are also validated against the target OS.

spirv_type.zig
const std = @import("std");

const Image = @SpirvType(.{ .image = .{
    .usage = .{ .sampled = f32 },
    .format = .unknown,
    .dim = .@"2d",
    .depth = .not_depth,
    .arrayed = false,
    .multisampled = false,
    .access = .unknown,
} });
const SampledImage = @SpirvType(.{ .sampled_image = Image });

const texture = @extern(*addrspace(.constant) const SampledImage, .{
    .name = "texture",
    .decoration = .{ .descriptor = .{ .set = 0, .binding = 0 } },
});
const uv_in = @extern(*addrspace(.input) const @Vector(2, f32), .{
    .name = "uv",
    .decoration = .{ .location = 0 },
});
const color_out = @extern(*addrspace(.output) @Vector(4, f32), .{
    .name = "color",
    .decoration = .{ .location = 0 },
});

export fn main() callconv(.{ .spirv_fragment = .{} }) void {
    color_out.* = std.spirv.imageSampleImplicitLod(texture, uv_in.*);
}
Shell
$ zig build-obj spirv_type.zig -target spirv32-vulkan

Array Multiplication Syntax Removed §

Array multiplication syntax (a ** b) has been removed in favor of @splat.

Migration:

--- a/player/chromaprint.zig
+++ b/player/chromaprint.zig
@@ -35,7 +35,7 @@ pub const Chroma = struct {
     const max_index = @min(window_size / 2, freqToIndex(max_freq));
     const notes: [window_size]u8 = n: {
         @setEvalBranchQuota(window_size);
-        var result = [1]u8{0} ** window_size;
+        var result: [window_size]u8 = @splat(0);
         for (min_index..max_index) |i| {
             const freq = indexToFreq(i);
             const octave = freqToOctave(freq);
@@ -123,7 +123,7 @@ const RollingIntegralImage = struct {
     num_rows: u32,
 
     pub const init: RollingIntegralImage = .{
-        .data = [1]Float{0} ** data_size,
+        .data = @splat(0),
         .num_rows = 0,
     };

Added @divCeil §

The new @divCeil builtin performs integer division rounded toward positive infinity, complementing the existing @divTrunc, @divFloor, and @divExact builtins.

sample_code
@divCeil(5, 3) == 2
@divCeil(-5, 3) == -1

As with the other division builtins, caller guarantees that denominator != 0 and that result does not overflow.

No more std.math.divCeil(a, b) catch unreachable!

@hasDecl Returns true Only for Public Declarations §

Previously, @hasDecl returned true for public declarations and declarations in the same file. Now, the behavior is the same independently of which file @hasDecl is in.

hasdecl.zig
const std = @import("std");

const Foo = struct {
    bar: i32,

    const baz = 1;
    pub var quux = "xxx";
};

test "@hasDecl example" {
    try std.testing.expect(!@hasDecl(Foo, "bar"));
    try std.testing.expect(!@hasDecl(Foo, "baz")); // different in 0.17.0
    try std.testing.expect(@hasDecl(Foo, "quux"));
}
Shell
$ zig test hasdecl.zig
1/1 hasdecl.test.@hasDecl example...OK
All 1 tests passed.

Allow Dereference and Coercion to Array Pointer of comptime Length Slices §

Now allowed:

sample_code
const slice: []const u16 = &.{ 1, 2, 3 };
const array: [3]u16 = slice.*;
const array_ptr: *const [3]u16 = slice;

void{} Syntax Removed §

void{} is no longer valid syntax. Use {} instead (#15213).

errdefer Capture Removed §

sample_code
errdefer |err| {
    // `err` was the error being returned; you could do stuff with it!
    // Like a normal `defer/`errdefer`, you can't `return` or `try` in this block, so you can't change
    // which error is returned; but you can e.g. log it
}

The capture (|err|) is no longer allowed (#23734).

To migrate, split the function into two:

fn processOneTarget(job: Job) void {
-    errdefer |err| std.debug.panic("panic: {s}", .{@errorName(err)});
+    processOneTargetInner(job) catch |err| std.debug.panic("panic: {s}", .{@errorName(err)});
+}
+fn processOneTargetInner(job: Job) !void {
     const target = job.target;

i0 Removed §

i0 is no longer an allowed primitive integer type.

This type was nonsensical, so does not have a direct alternative. However, any uses of it can almost certainly be transparently replaced with u0.

The internal and link_once tags of std.lang.GlobalLinkage have been removed as they had unclear semantics and incomplete support in codegen and linking (#36956). Any use of link_once is likely served by weak, while the replacement for internal is to simply not @export the symbol in the first place.

Standard Library §

Deprecations §

StackFallbackAllocator Reworked §

StackFallbackAllocator is an abstraction that is useful for the "small vec" optimization, in which common cases can fit on a pre-allocated stack buffer, but rare cases need dynamic heap allocation. The previous design had a few problems:

Now, the buffer is provided as an argument, like most other std APIs that need a buffer.

Migration guide:

sample_code
var stack align(@max(
    @alignOf(std.heap.StackFallbackAllocator(0)),
    @alignOf(Item)),
) = std.heap.stackFallback(@sizeOf(Item), self.gpa);
const allocator = stack.get();

⬇️

sample_code
var stack_buf: [1]Item = undefined;
var stack: std.heap.StackFallbackAllocator = .init(@ptrCast(&stack_buf), gpa);
const allocator = stack.allocator();

SafeAllocator Introduced §

std.heap.DebugAllocator is replaced by a thread-safe allocator with the following guarantees:

Given the backing allocator does not reuse memory, it does not reuse memory either and most writes after free will segmentation fault or are eventually detected and panic.

std.heap.DebugAllocator and std.heap.Check are deprecated.

Every allocation is trailed by an AllocFooter which contains metadata for the allocation and stack traces. It is protected by a checksum to catch corruption from allocation overwrites and report canary mismatches. An allocation's memory has a minimum alignment of AllocFooter so that the footer is at a fixed offset determined from the allocation size. An allocation's memory is stored either:

To track allocations, each thread maintains a table of backing allocations. The table may be modified by other threads in the case of a producer-consumer operation, so the table is a linked list only expanded by creating new segments. Each thread maintains a linked list of free entries, which may contain entries from other threads' tables.

In the case of producer-consumer operations, acquire/release ordering is assumed to be provided externally. This is also assumed by all other thread-safe allocators that reuse memory as otherwise there would be data races on reuse of allocated memory.

Two fuzz tests have also been added for the allocator. They check that there is no memory reuse, that returned memory is writable, and that it is not overwritten. The multi-threaded fuzz test spawns a number of worker threads which are used for all the test runs. I have run these tests extensively under TSAN.

Building the standard library tests with an -Osafe compiler build and -Ddebug-allocator:

Benchmark 1 (3 runs): ./master-out/bin/zig test --zig-lib-dir lib lib/std/std.zig -femit-bin=test --test-no-exec
  measurement          mean ± σ            min … max           outliers         delta
  wall_time          29.4s  ±  157ms    29.2s  … 29.5s           0 ( 0%)        0%
  peak_rss           2.24GB ± 3.49MB    2.23GB … 2.24GB          0 ( 0%)        0%
  cpu_cycles          143G  ±  999M      142G  …  144G           0 ( 0%)        0%
  instructions        268G  ± 5.22M      268G  …  268G           0 ( 0%)        0%
  cache_references   13.1G  ± 88.8M     13.0G  … 13.2G           0 ( 0%)        0%
  cache_misses       2.38G  ± 30.7M     2.35G  … 2.41G           0 ( 0%)        0%
  branch_misses       634M  ± 6.22M      629M  …  641M           0 ( 0%)        0%
Benchmark 2 (3 runs): ./branch-out/bin/zig test --zig-lib-dir lib lib/std/std.zig -femit-bin=test --test-no-exec
  measurement          mean ± σ            min … max           outliers         delta
  wall_time          22.1s  ± 88.6ms    22.0s  … 22.2s           0 ( 0%)        ⚡- 24.7% ±  1.0%
  peak_rss           1.11GB ±  799KB    1.11GB … 1.11GB          0 ( 0%)        ⚡- 50.3% ±  0.3%
  cpu_cycles          136G  ±  480M      136G  …  137G           0 ( 0%)        ⚡-  4.4% ±  1.2%
  instructions        273G  ± 2.07M      273G  …  273G           0 ( 0%)        💩+  1.6% ±  0.0%
  cache_references   12.3G  ± 71.3M     12.2G  … 12.4G           0 ( 0%)        ⚡-  6.0% ±  1.4%
  cache_misses       2.02G  ± 11.5M     2.01G  … 2.03G           0 ( 0%)        ⚡- 14.9% ±  2.2%
  branch_misses       569M  ± 2.65M      567M  …  572M           0 ( 0%)        ⚡- 10.2% ±  1.7%

ArrayList §

Upgrade guide:

sample_code
if (list.getLastOrNull()) |foo| {
    // ...
}
const foo = list.getLast();

⬇️

sample_code
if (list.last()) |foo| {
    // ...
}
const foo = list.last().?;

ArrayList Pointer Stability §

This is an enhancement that can help track down ArrayList usage bugs faster (#36239).

Devlog Entry

debug.SafetyLock Gains Support for Shared Locking §

The existing lock and unlock methods continue to act exclusively. They should be used when data may be mutated. New methods, lockShared and unlockShared, may be used for shared locking in situations where multiple independent users are reading but not mutating data.

fmt.allocPrint moved to mem.Allocator §

sample_code
try std.fmt.allocPrint(arena, "{s}={d}", .{ x, y });

⬇️

sample_code
try arena.print("{s}={d}", .{ x, y });

Formatted Printing Enhancements §

The "{q}" specifier which escapes strings so that they can appear in double-quoted string literals has relaxed escaping rules such that UTF-8 encoded data can pass through unmangled.

"{qf}" is introduced for double-quote escaping the output of a format().

std.zon.parse Reworked §

std.zon.parse now takes struct args and allocates its result from an arena.

Migration guide:

sample_code
var diag: Diagnostics = .{};
defer diag.deinit(gpa);
const result = std.zon.fromSlice(
    MyZonType,
    gpa,
    source,
    &diag,
    .{},
) catch |err| switch (err) {
    error.ParseZon => std.process.fatal("input.zon: {f}", .{diag}),
    error.OutOfMemory => |e| return e,
};
defer std.zon.parse.free(result);

⬇️

sample_code
var diag: Diagnostics = undefined;
const result = std.zon.fromSlice(MyZonType, .{
    .gpa = gpa,
    .arena = arena,
    .source = source,
    .diagnostics = &diag,
}) catch |err| switch (err) {
    error.ParseZon => diag.fatal("input.zon"),
    error.OutOfMemory => |e| return e,
}

Some methods were renamed:

"updateFrom" variants such as updateFromSlice were added. These update an in memory value, overwriting the value's fields with fields specified in the ZON source. This can be useful when using ZON to load configuration files with varying precedence, for example a text editor that has a global config file and a per-project config file.

Rename bit_set Variants and Deprecate the Managed One §

Renames the types for consistency, deprecating the previous names and the managed variant.

Struct-Of-Arrays Style for std.lang.Type §

When doing type reflection, structs and unions return their information in struct-of-arrays style (#35234).

--- a/lib/compiler/Maker/ScannedConfig.zig
+++ b/lib/compiler/Maker/ScannedConfig.zig
@@ -49,9 +49,10 @@ pub fn print(sc: *const ScannedConfig, w: *Writer) Writer.Error!void {
 }
 
 fn printStruct(sc: *const ScannedConfig, s: *Serializer.Struct, comptime S: type, v: S) !void {
-    inline for (@typeInfo(S).@"struct".fields) |field| {
-        try s.fieldPrefix(field.name);
-        try printValue(sc, s.container.serializer, field.type, @field(v, field.name));
+    const info = @typeInfo(S).@"struct";
+    inline for (info.field_names, info.field_types) |field_name, field_type| {
+        try s.fieldPrefix(field_name);
+        try printValue(sc, s.container.serializer, field_type, @field(v, field_name));
     }
 }

Rename lang.OptimizeMode to lang.Optimize §

And remove "release" from the enum tag names.

No functional change, however, despite the addition of backwards-compatibile declarations in this patch, it is breaking because expressions that use == or != operators will not able to use the deprecated names.

lang.Optimize.runtimeSafety §

std.lang.Optimize.runtimeSafety is preferred as an alternative to std.debug.runtime_safety since it will offer callsites knowledge about their own module rather than standard library module.

@import("builtin") Deprecations §

The redundant constants cpu, os, abi, and object_format in @import("builtin") have been deprecated and will be removed in 0.18.0. Please replace any usage with the corresponding fields on the target constant:

Handle Floats Correctly in mem.eql and mem.findDiff §

The functions std.mem.eql and std.mem.findDiff short-circuit when their two inputs are slices to the same memory. This short-circuiting is only correct when the == operator, for the given type, is reflexive. This isn't the case for floats, as for example std.math.nan(f64) != std.math.nan(f64). The change in this PR disables that optimisation when working on float slices.

Previously-failing, now-succeeding tests:

sample_code
const x: [3]f64 = .{ 42.0, std.math.nan(f64), 3.1415 };
try std.testing.expect(!std.mem.eql(f64, &x, &x));
try std.testing.expectEqual(1, std.mem.findDiff(f64, &x, &x));

Decouple Uri and net.HostName §

Uri was sometimes using HostName.validate for host (in resolveInPlace) and sometimes not (in parseAfterScheme). On its own, this was a problem, but the bigger problem is that RFC3986 (Uri) has a much different idea of what a valid host name is than RFC1123 (HostName), and so just making Uri consistently use HostName.validate would make Uri less useful overall.

Instead, all HostName-related stuff has been removed from Uri. Uri.getHost has been moved to HostName.fromUri (without a graceful deprecation, since the semantics are different enough for users to need to evaluate usage sites), while Uri.getHostAlloc has been removed entirely.

Migration guide:

sample_code
var host_buf: [HostName.max_len]u8 = undefined;
const host = try uri.getHost(&host_buf);

⬇️

sample_code
var host_buf: [HostName.max_len]u8 = undefined;
// note: the error set is different than it was before since fromUri does validation
const host = try HostName.fromUri(uri, &host_buf);

#36036

Build System §

Separate the Maker Process from the Configurer Process §

zig build now runs projects' build.zig code in a separate executable than the one that performs Package Management and executes the build graph, making zig build faster for several reasons (#35428):

Furthermore, configuration is now serialized into a compact binary format that can be consumed by third party tooling and is part of the new Build Server Protocol. The prior way of satisfying this use case by forking the build runner is no longer supported.

To render configuration as .zon to stdout, pass --print-configuration.

Cache System Reworked §

New features:

All four combinations are possible (is_directory=true/false, metadata_mode=true/false). These features are exposed as new API in the Build System.

Since the Zig toolchain is heavily reliant on the caching system, this release also switches to a binary format, saving roughly 25% on file size, which eases a bit of pressure on the file system cache while also simplifying the work the computer needs to do - directly copy bytes from disk rather than parsing text files. The new zig cache-cat subcommand is available for troubleshooting or tinkering with files inside a zig-cache directory.

The cache system also now has the capability to explain why a "miss" happened. The public-facing API of std.Build.Cache has many breaking changes, but outside of compiler tooling, this is an uncommon API to be used, and all the changes make it harder to misuse.

This change has been observed to speed up cache hits by 5-10% (#36822).

Introduce the Concept of Configure Cache Poisoning §

If the cache is poisoned means that the configure logic had side effects, or otherwise did something that could not be tracked by the cache system.

This is not to be confused with whether individual steps may have side effects when being evaluated; it has to do with the logic inside build.zig itself. For example, a Run step that prints "hello world" has side effects at make time and therefore does not warrant setting this flag, while checking for the existence of scdoc at configure time in order to choose the default value for a configuration option does.

Keeping the cache pure will make zig build faster, bypassing the configurer process when identical configuration would be generated.

When the cache is poisoned, the maker process will delete the build configuration file upon ingesting it since it cannot be reused.

Ways to poison the cache include calling findProgram, or more directly std.Build.Graph.poisonCache. A better alternative than cache poisoning is to explicitly declare the configuration dependencies with these new functions:

Advanced users can override the cache poisoning behavior with a new CLI option:

  --cache-poison[=mode]        Override configuration caching behavior
      pure                     (default) Avoid false positive cache hits
      poisoned                 Don't cache the configuration
      disallowed               Panics when cache would be poisoned
      ignored                  A little poison never hurt anybody

findProgram §

Immediately (in the configure phase), searches for an executable on the host that has more than one possible name.

Names are searched in order, observing search prefixes first and then PATH environment variable.

Calling this function poisons the configuration cache, so it is only appropriate when the existence of the program or its output needs to be observed by configuration logic. That's why there is also findProgramLazy now.

findProgramLazy §

Creates an anonymous Step that searches for an executable on the host that has more than one possible name.

Unlike findProgram, this function does not poison the configuration cache, however the result cannot be used in the configuration phase, hence the return type being LazyPath.

Returns the LazyPath of the found executable. The search only takes place if the LazyPath will be used by a depending Step.

This API is useful in the following cases:

Run Step: Passthru Args §

In the Run step, passthru args are all together now, not observable in configure phase whether run args are provided.

--- build.zig
+++ build.zig
@
-if (b.args) |args| {
-    run_cmd.addArgs(args);
-}
+run_cmd.addPassthruArgs();

This removes a capability from build scripts since they can no longer observe those arguments. In exchange, it means that when changing those arguments, build scripts no longer must be rebuilt from source.

Fmt Step: Options §

paths and exclude_paths are now LazyPath lists. There is a convenience method to create them: b.pathList.

--- build.zig
+++ build.zig
@
-    const fmt_include_paths = &.{ "lib", "src", "test", "tools", "build.zig", "build.zig.zon" };
-    const fmt_exclude_paths = &.{ "test/cases", "test/behavior/zon" };
+    const fmt_include_paths = b.pathList(&.{ "lib", "src", "test", "tools", "build.zig", "build.zig.zon" });
+    const fmt_exclude_paths = b.pathList(&.{ "test/cases", "test/behavior/zon" });

Step.Options: add addOptionPathDirectory §

Now, when adding an option that is a file path, one must explicitly choose between (#36876):

Lazy Dependency Ergonomic Enhancements §

Removed Ability to Override Build Runner §

There is no concept of a "build runner" any more; it has been split into: configurer and maker

This use case is now handled by the Build Server Protocol.

Package Management §

All package management functionality has been moved out of the Compiler and into the Build System. This includes the following sub-commands:

This means that large parts of what used to be included in the compiler executable are now shipped in source form instead, including:

All of this functionality is now compiled in -Osafe optimization mode rather than -Ofast due to being in the compiler. When hacking on the build system itself, the environment variable ZIG_DEBUG_CMD=1 may be used to compile the build system in debug mode instead.

Miscellaneous changes:

Ability to Override Package Path §

--pkg-path CLI arg and ZIG_LOCAL_PKG_DIR env var are now observed for both fetch and build commands.

Global vs Local Fetching §

Now zig fetch only fetches into the global cache, just like it used to. However, if --save (or any variant) is used, then it also fetches into the local package path. When fetching globally, does not require build.zig to be present. zig build always fetches locally (in addition to globally).

Notably, this fixes the regressed use case zig fetch .

When fetching by path, the hash is always computed, recompressed tarball is always created, always overwrites any existing global cache entry.

Slight Difference in PATH for DLL Arguments §

It used to be the case that, when targeting Windows or Wine, artifact args added to Run steps modified PATH based on the set of directories containing the recursive set of DLL dependencies. Now this is only done for argv[0]. The motivation for also doing this for the other command line arguments is unclear, since those DLLs don't need to be loaded in order to execute argv[0].

Build Server Protocol §

Now, when --listen=- is passed, the build system serves a protocol that allows connected clients to monitor and control the build graph as it executes. This is intended to be consumed by third-party tooling such as IDEs.

Current things you can do:

In particular, the separation of maker process and configurer process is a breaking change that prevents the ZLS project from working with 0.17.0. Although some progress was made to restore functionality in this release cycle, Zig team and ZLS team are still working together to enhance the build server protocol further to the point that ZLS can not only restore functionality, but surpass the power and capabilities compared to before.

In the future it is expected for much of Zig's own first-party build system tooling to become a client of the build server protocol, dogfooding it to ensure that third-party tooling enjoys equivalent capabilities (#36497).

It is also planned for the build server to multiplex compiler server protocol for the compilation steps, providing type-system information, refactoring, and other advanced editing capabilities (#615).

Compiler §

Incremental Compilation §

The Zig compiler's implementation of incremental compilation—a feature allowing near-instant rebuilds of projects after changing the code—has been significantly improved in Zig 0.17.0. Many bugs have been fixed, and the new ELF Linker introduced in the previous release has gained good support for the feature.

Thanks to these enhancements, it is now possible for most projects targeting x86_64-linux to take advantage of incremental compilation. To do so, add the arguments -fincremental --watch to your zig build command (e.g. zig build -fincremental --watch)—this will cause the Zig build system to listen for changes to source files, and react to them by performing an incremental rebuild.

For more information on ways to use incremental compilation in your own projects, or to learn more about how this feature works under the hood, consider checking out this blog post by a Zig core team member.

Future releases will continue to focus on improving this feature, including introducing a new Mach-O linker and self-hosted aarch64 Backend with good support for incremental compilation; adding support for using incremental compilation without --watch; and fixing any remaining bugs.

SPIR-V Backend §

The self-hosted SPIR-V backend is now multi-threaded like the other backends.

Execution modes such as LocalSize and OriginUpperLeft are now derived from the function's calling convention instead of being set through inline assembly, and the new spirv_task and spirv_mesh calling conventions add support for task and mesh shaders (#35676).

Declaring capabilities and extensions in inline assembly with OpCapability and OpExtension is no longer allowed. They are enabled through target CPU features instead, i.e. the -mcpu option.

22 bugs were fixed in the SPIR-V backend during this release cycle.

aarch64 Backend §

Progress towards this is blocked on Linker enhancements, many of which were completed during this release cycle.

loongarch Backend §

Initial implementation of self-hosted backend for loongarch64 has been contributed (#36418). It is still experimental and not yet usable. There are two ways to contribute to this backend: working on it directly, and contributing to AIR Legalization Features, which helps all unfinished backends reach the finish line quicker.

WebAssembly Backend §

Zig's WebAssembly backend is now passing 2060/2054 (100%) behavior tests compared to the LLVM backend. However, it is not yet the default when compiling in debug optimization mode due to lack of debug info support (#37032).

Linker §

ELF §

This release makes significant progress towards replacing Zig's legacy self-hosted ELF linker with its new implementation introduced in the previous release. Specific enhancements include:

While this linker has not quite reached feature parity with our old self-hosted ELF linker yet—and so remains disabled by default—it is already capable in practice of building the vast majority of Zig projects targeting x86_64-linux. This unlocks the ability to use Incremental Compilation for these projects—like in Zig 0.16.0, the new linker is enabled by default in this case.

In the next release of Zig, we hope to fully eliminate the legacy ELF linker in favour of this implementation.

COFF §

COFF support in the linker is enhanced with the following features (#35674):

New Linker Testing Framework §

Zig is moving towards snapshot-based testing for its linkers.

Tests are a combination of comparing objdump snapshot output, actually running the artifacts, and checking for linker errors.

zig build -Dlink-snapshot-update causes tests to run in a mode that outputs snapshots instead of checking against them.

A typical workflow for adding a new test:

  1. Add the test
  2. zig-debug build test-link -Dtest-filter=my-test -Dlink-snapshot-update
    • This will output a .dmp file for all the snapshot combinations defined in any verifyObjdump calls.
    • A single snapshot intentionally aliases between many targets to reduce noise in the snapshot folder, so snapshot updates are made by whichever test runs first for that snapshot name. If differences between targets do exist, they will be revealed in step 4.
  3. Inspect the snapshot output for correctness.
  4. zig-debug build test-link -Dtest-filter=my-test
    • This will now run all targets against the newly added snapshots
  5. If there are now snapshot failures, that means different targets had different snapshot outputs. The output should be inspected to see if these results are indeed valid differences. If they are, then the scope parameter should be used to cause -Dlink-snapshot-update to output snapshot to different filenames, scoped on the diference.
  6. Re-run -Dlink-snapshot-update to update the new set of snapshots.

SPIR-V §

The SPIR-V linker has been rewritten (#36828). It now supports incremental compilation and can link external .spv object files.

Fuzzer §

Although this release's Build System changes are loosely related to Zig's integrated fuzzer and its interaction with the build system, no changes were made to the fuzzer itself.

We expect to focus on improving the fuzzer in a future release cycle.

Bug Fixes §

Full list of the 329 bug reports closed during this release cycle:

Many bugs were both introduced and resolved within this release cycle. Most bug fixes are omitted from these release notes for the sake of brevity.

This Release Contains Bugs §

Zig has known bugs, miscompilations, and regressions.

Even with Zig 0.17.x, working on a non-trivial project using Zig may require participating in the development process.

When Zig reaches 1.0.0, Tier 1 support will gain a bug policy as an additional requirement.

Notable Regressions §

We are aware of these notable regressions in 0.17.0:

Toolchain §

LLVM 22 §

This release of Zig upgrades to LLVM 22.1.8. This covers Clang (zig cc), libc++, libc++abi, libunwind, and libtsan as well.

Loop Vectorization Disabled to Work Around Regression §

In the previous release of Zig, we were forced to disable a key LLVM optimization pass—loop vectorization—to work around a miscompilation which affected the Zig compiler.

Since we first introduced that workaround, a fix has been merged into LLVM's main branch. However, the fix is not available in LLVM 22, the LLVM version used by Zig 0.17.0. Therefore, this workaround remains enabled for now.

Zig 0.18.0 will upgrade to LLVM 23, so will allow us to re-enable this optimization pass.

musl 1.2.5 §

Zig 0.17.0 distributes musl 1.2.5 plus backported security and portability fixes. Meanwhile, upstream has tagged 1.2.6. Zig 0.18.0 will update to musl 1.2.6.

When targeting musl statically, many functions are now provided by zig libc rather than source files copied from musl. Therefore, if you encounter bugs with musl libc provided by Zig, please respect upstream by reporting them to Zig's issue tracker rather than musl's.

glibc 2.44 §

glibc version 2.44 is now available when cross-compiling.

Linux 7.2 Headers §

This release includes Linux kernel headers for version 7.2.

macOS 27.0 Headers §

This release includes macOS system headers for version 27.0.

MinGW-w64 §

Zig 0.17.distributes MinGW-w64 commit 31bd54ab7d5fe03c67ed2bb1a57e531b9c7f8cc4.

However, many functions are now provided by zig libc rather than source files copied from MinGW-w64. Therefore, if you encounter bugs with MinGW-w64 libc provided by Zig, please respect upstream by reporting them to Zig's issue tracker rather than MinGW-w64's.

NetBSD 11.0 libc §

NetBSD libc version 11.0 is now available when cross-compiling.

OpenBSD 7.9 libc §

OpenBSD libc version 7.9 is now available when cross-compiling.

WASI libc §

Zig 0.17.0 continues to distribute WASI libc commit c89896107d7b57aef69dcadede47409ee4f702ee.

However, many functions are now provided by zig libc rather than source files copied from WASI libc.

Furthermore, starting with Zig 0.18.0, instead of distributing third party WASI libc code, Zig will provide libc for WASI targets via zig libc. For more information, see:

zig libc §

In libc.txt files, the gcc_dir field has been renamed to cc_dir to reflect the reality that it is not specific to GCC. The old name will still be accepted for now, but users are encouraged to migrate their libc.txt to the new name (#36951).

Additionally, cc_dir is now required on Linux targets. Note that, because Android and OpenHarmony store the relevant object files in an unusual location, users of these targets will likely want to set cc_dir to the same path as crt_dir.

zig cc §

zig cc and zig c++ are now based on Clang 22.1.8.

zig objdump §

This was a requirement for snapshot testing, as well as aiding in developing the COFF Linker.

Supported features:

Usage: zig objdump [options] file

Options:
  -h, --help                         Print this help and exit
  --all-headers                      Alias for --file-headers --linker-member=2 --member-headers --section-headers --relocs --symbols
  --exports[=sort]                   Display exported symbols.
                                     In the case of COFF import libraries, displays the symbol list and import headers.
                                     Specify =sort to optionally sort the import headers by symbol name.
  --file-headers                     Display file-format specific headers
  --imports                          Display imported symbols
  --linker-member[=1|2|longnames]    (Coff) Display contents of the specified archive linker member (default 2)
  --member-headers                   Display archive member headers
  --elements=[e1],[e2],-[e3],...     Select which formatting elements are displayed. Intended for snapshot testing.
      file-type                      File type summary
      header-name                    Name that precedes a header block
      member-path                    Display full member paths. If removed, only basenames will be used.
      newlines                       Newlines between output sections
      table-header                   Table headers with column names
      all                            (default) All of the above
  --only-member=[name]               Only consider archive members names that contain [name]. Can be specified multiple times.
  --only-section=[name]              Only consider section names that contain [name]. Can be specified multiple times.
  --only-symbol=[name]               Only consider symbol names that contain [name]. Can be specified multiple times.
  --redact=[kind]                    Redact the specified field kind. Intended for snapshot testing.
      rva                            Relative virtual addresses
      va                             Virtual addresses and file offsets
      ord                            Symbol ordinals / hints
      size                           Sizes and lengths
      all                            All of the above
  --relocs                           Display relocations
  -s, --snapshot                     Alias for --redact=all --elements=-all
  --section-headers                  Display section headers
  --strings                          Display string tables
  --symbols                          Display symbol tables
  --tls                              Display TLS information

Some example output:

❯ zig objdump mathtest-dync-exe-no-llvm.dll --all-headers
mathtest-dync-exe-no-llvm.dll: PE/COFF image


COFF Header:
            8664 machine (AMD64)
               7 number_of_sections
        6a08670a time_date_stamp
               0 pointer_to_symbol_table
               0 number_of_symbols
              f0 size_of_optional_header
            2022 flags
               | EXECUTABLE_IMAGE
               | LARGE_ADDRESS_AWARE
               | DLL

COFF Optional Header:
             20b magic (PE32+)
           14.00 linker_version
          14a400 size_of_code
           84e00 size_of_initialized_data
               0 size_of_uninitialized_data
            1000 address_of_entry_point (       180001000)
            1000 base_of_code (       180001000)
       180000000 image_base
            1000 section_alignment
             200 file_alignment
            6.00 operating_system_version
            1.00 image_version
            6.00 subsystem_version
               0 win32_version_value
          1d6000 size_of_image
             400 size_of_headers
               0 checksum
               2 subsystem (WINDOWS_GUI)
             160 dll_flags
               | HIGH_ENTROPY_VA
               | DYNAMIC_BASE
               | NX_COMPAT
          100000 size_of_stack_reserve
            1000 size_of_stack_commit
          100000 size_of_heap_reserve
            1000 size_of_heap_commit
               0 loader_flags
              10 number_of_rva_and_sizes

Data Directories:
          1b48d0       54 EXPORT
          1b4924       8c IMPORT
               0        0 RESOURCE
          1cc000     633c EXCEPTION
               0        0 SECURITY
          1d4000     1280 BASERELOC
          1bc000       1c DEBUG
               0        0 ARCHITECTURE
               0        0 GLOBALPTR
          1aebc8       28 TLS
               0        0 LOAD_CONFIG
               0        0 BOUND_IMPORT
          1b4c80      2d0 IAT
               0        0 DELAY_IMPORT
               0        0 COM_DESCRIPTOR
               0        0 RESERVED

Sections in 'mathtest-dync-exe-no-llvm.dll':
Num Name          RVA Virt Size Data Size   & Data & Relocs  & Lines # Relocs  # Lines    Flags
  1 .text        1000    14a346    14a400      400        0        0    0    0 60000020 | CNT_CODE MEM_EXECUTE MEM_READ
  2 .rdata     14c000     6fe3c     70000   14a800        0        0    0    0 40000040 | CNT_INITIALIZED_DATA MEM_READ
  3 .buildid   1bc000        52       200   1ba800        0        0    0    0 40000040 | CNT_INITIALIZED_DATA MEM_READ
  4 .data      1bd000      e2a0      d200   1baa00        0        0    0    0 c0000040 | CNT_INITIALIZED_DATA MEM_READ MEM_WRITE
  5 .pdata     1cc000      633c      6400   1c7c00        0        0    0    0 40000040 | CNT_INITIALIZED_DATA MEM_READ
  6 .tls       1d3000        20       200   1ce000        0        0    0    0 c0000040 | CNT_INITIALIZED_DATA MEM_READ MEM_WRITE
  7 .reloc     1d4000      1280      1400   1ce200        0        0    0    0 42000040 | CNT_INITIALIZED_DATA MEM_DISCARDABLE MEM_READ

No symbol table found

If this output was used for a snapshot test that wanted to test the presence of a particular export:

❯ zig objdump mathtest-dync-exe-no-llvm.dll --exports --only-symbol=add --redact=rva --elements=-all
Export directory:
               0 flags
               0 time_date_stamp
            0.00 version
xxxxxxxxxxxxxxxx name_rva
               1 ordinal_base
               1 number_of_entries
               1 number_of_names
xxxxxxxxxxxxxxxx export_address_table_rva
xxxxxxxxxxxxxxxx name_pointer_table_rva
xxxxxxxxxxxxxxxx ordinal_table_rva
   1    0 xxxxxxxx | add

The redaction (--redact=) and element removal (--elements=) functionality is used to remove parts of the output that don't matter for the particular test, as to not cause spurious failures if say, an RVA for a symbol changes due to some unrelated change to the linker. -s is shorthand which enables all the redacts and removes all extra output elements, but particular tests may not use this if they do care about specific values.

resinator §

Windows Resource Compilation Moving to an External Package §

Windows resource script compilation will be moved out of the compiler and into an official-but-external build system package in the next release. As such, the corresponding std.Build functions and fields (Build.Module.addWin32ResourceFile, etc) have been marked as deprecated in this release.

The zig rc subcommand will remain after this change in order to continue supporting the use case of using the Zig toolchain with other build systems.

zig fmt §

Added --complexity Flag §

It's a simple tool for counting tokens and AST nodes, which can be used to share how an edit to a source file increases or reduces complexity with a heuristic that is more insightful than line count.

For example, running it on old ELF linker directory:

info: src/link/Elf/gc.zig: tokens=1538 nodes=770
info: src/link/Elf/Atom.zig: tokens=15576 nodes=7768
info: src/link/Elf/Merge.zig: tokens=2288 nodes=1092
info: src/link/Elf/Thunk.zig: tokens=1128 nodes=519
info: src/link/Elf/SharedObject.zig: tokens=4566 nodes=2236
info: src/link/Elf/eh_frame.zig: tokens=4840 nodes=2335
info: src/link/Elf/Symbol.zig: tokens=3770 nodes=1872
info: src/link/Elf/synthetic_sections.zig: tokens=13287 nodes=6375
info: src/link/Elf/Object.zig: tokens=13903 nodes=6842
info: src/link/Elf/LinkerDefined.zig: tokens=4140 nodes=2091
info: src/link/Elf/relocatable.zig: tokens=3598 nodes=1848
info: src/link/Elf/Archive.zig: tokens=2176 nodes=1028
info: src/link/Elf/ZigObject.zig: tokens=20783 nodes=10274
info: src/link/Elf/AtomList.zig: tokens=1819 nodes=933
info: src/link/Elf/relocation.zig: tokens=1289 nodes=551
info: src/link/Elf/file.zig: tokens=2330 nodes=1087
info: total: tokens=97031 nodes=47621

Another example is after editing Lld.zig to use arena.print rather than std.fmt.allocPrint. The line count is roughly the same but --complexity tells a different story:

In the future this metric may be helpful for an automatic import organizer to determine whether to create an import alias or not.

Roadmap §

  1. Work with ZLS team to enhance Build Server Protocol to the point where satisfies all their use cases.
  2. Complete Windows support in the x86_64 backend so that it can be enabled by default.
  3. Complete and stabilize the language.
  4. Complete the aarch64 Backend and make it the default backend for debug mode.
  5. Enhance the Linker implementations, eliminating dependency on LLD and support Incremental Compilation.
  6. Enhance the integrated Fuzzer to be competitive with AFL and other state-of-the-art fuzzers.
  7. Transition from a library dependency on LLVM to a process dependency on Clang (#16270).
  8. Complete the Build System, in particular Package Management features.
  9. Audit the Standard Library (#1629).

Thank You Contributors! §

Ziggy the Ziguana

Here are all the people who landed at least one contribution into this release:

Thank You Sponsors! §

Ziggy the Ziguana

Special thanks to those who sponsor Zig. Because of diverse, recurring donations, Zig is driven by the open source community, rather than the goal of making profit. In particular, those below sponsored Zig for an average of $50/month or more during this release cycle using our preferred donation platform:

Special thanks also to TigerBeetle, Synadia Communications, and ZML for substantial contributions.