# Cross-compilation

> Every target, out of the box.

Cross-compilation is not a special mode in Zig. It is a flag:

```bash
zig build-exe main.zig -target x86_64-linux-gnu
zig build-exe main.zig -target aarch64-macos
zig build-exe main.zig -target x86_64-windows-gnu
zig build-exe main.zig -target wasm32-wasi
```

No cross toolchain to install, no sysroot to assemble. Zig ships libc sources
for the targets it supports and builds what it needs on demand.

```bash
zig targets       # everything available
```

## The triple

`<arch>-<os>-<abi>`, with `native` allowed in any position:

```
x86_64-linux-gnu
x86_64-linux-musl      # static linking without glibc's baggage
aarch64-macos-none
wasm32-wasi
native-native-musl
```

The ABI field matters more than people expect. `musl` produces a genuinely
static binary; `gnu` links against glibc and inherits its version
compatibility rules.

## Targeting a specific CPU

```bash
zig build-exe main.zig -target x86_64-linux -mcpu=znver3
zig build-exe main.zig -mcpu=baseline        # maximum portability
```

`baseline` is the conservative choice: no assumptions beyond the architecture
minimum. Naming a specific CPU lets the optimiser use its instructions, at the
cost of not running on older ones.

## In `build.zig`

```zig
const target = b.standardTargetOption(.{});
```

That exposes `-Dtarget=` to whoever runs your build, so users can cross-compile
your project without you doing anything else.

## Compiling C too

`zig cc` is a drop-in C compiler with the same cross-compilation story, which
is why some projects adopt Zig purely as a build tool for their existing C.