Zig on this Mac

The installed toolchain is master, not a release: 0.18.0-dev.120+9fe22a29b through zvm at /Users/donaldfilimon/.zvm/bin/zig. Measured 2026-10-10.

Read this before writing a line of Zig

Master has removed constructs that pretraining, tutorials, and Stack Overflow all still teach. These are compiler errors, not warnings, and each was confirmed by compiling on this machine:

You will reach for	It gives	Use instead
@cImport / @cInclude	invalid builtin function	zig translate-c, or b.addTranslateC
@Type(...)	invalid builtin function	@Int, @Struct, @Enum, @Union, @Fn, @Pointer, @Tuple
errdefer |err|	expected block or expression, found '|'	plain errdefer, destructure in a wrapper
callconv(.C)	no member named 'C'	callconv(.c)
std.heap.GeneralPurposeAllocator	no member named	std.heap.SafeAllocator
std.io.getStdOut()	gone	Io.File.Writer off init.io
std.fs.cwd()	no member named 'cwd'	Io.Dir.cwd()
ArrayList(T).init(gpa)	gone	ArrayList is unmanaged; pass the allocator per call
@typeInfo(S).Struct.fields	gone	.@"struct" with field_names / field_types
std.meta.fields	@compileError	the parallel arrays above

std.builtin is a deprecated alias for std.lang, and std.fs is a 21-line shim. If a Zig answer feels familiar, that is a reason to check it, not to trust it.

Two authorities, and they answer different questions

Compiling proves removal. The langref proves deprecation. @intFromEnum compiles and passes today while ~/.zvm/master/doc/langref.html says "Deprecated. Use @backingInt or @bitCast instead", so a green test is not evidence a construct is current. The langref ships with the toolchain and its version stamp matches zig version exactly. Read both.

Never answer a Zig question from memory. Read /Users/donaldfilimon/.zvm/master/lib/std/, then compile the answer in /private/tmp.

Where to go

• [[zig-toolchain]] first for anything environmental: which zig is active, the dangling ~/.zvm/current symlink, the second zig on PATH, where the langref and stdlib source live, scratch-path rules.
• [[zig-types]] for the type system: pointers, slices, sentinels, optionals, error unions, structs, enums, unions, vectors, coercion, casting.
• [[zig-errors]] for error sets, try, catch, errdefer, error return traces, and when to use unreachable or assert instead of an error.
• [[zig-memory]] for allocators, ownership discipline, alignment, and the leak-checked test pattern.
• [[zig-comptime]] for generics, inline, @TypeOf, @typeInfo, reflection, and the comptime failure modes.
• [[zig-builtins]] for the @-builtin reference: 128 recognized, 126 usable.
• [[zig-std]] for the standard library map: containers, fmt, mem, json, http, crypto, math, sort, threads, time.
• [[zig-io]] for the std.Io rewrite: readers, writers, buffering, printing to stdout, and async under Io.Threaded. The most-changed surface; go here before any I/O or concurrency work.
• [[zig-build]] for build.zig, build.zig.zon, modules, steps, dependencies, and cross-compilation.
• [[zig-testing]] for test blocks, filters, std.testing, and fuzzing.
• [[zig-c-interop]] for extern, export, the C ABI, linking, and using zig cc as a cross compiler.

False greens seen on this toolchain

A --test-filter matching nothing prints All 0 tests passed and exits 0. A leaking test prints OK on its own line and fails only in the summary. Zig analysis is lazy, so a snippet nothing references can compile without being checked: give every test an explicit driver. And cmd | tail reports tail's exit status, not the command's, which has manufactured false green claims here before.

Projects using Zig here

Zig trees pin minimum_zig_version = "0.18.0-dev.120+9fe22a29b" (verified 2026-10-10): ~/dev/active/baseos, ~/dev/active/cell-lang, ~/dev/active/Gama, ~/dev/active/golive, ~/dev/active/Quesar. ~/dev/active/cell-lang is the Cell language compiler; read its AGENTS.md first, and always build it with -Dswift=false.

-Dswift=false is cell-lang's flag, not a universal one. ~/dev/active/Gama's current build.zig rejects it (error: invalid option: "swift"; the accepted options are target, cpu, ofmt, dynamic-linker, optimize, mlir-opt), so the older written instructions for Gama are stale. Read each project's build.zig option list before passing any -D flag.