noreturn

noreturn

noreturn is the type of:

• break
• continue
• return
• unreachable
• while (true) {}

When resolving types together, such as if clauses or switch prongs, the noreturn type is compatible with every other type. Consider:

test.zig

fn foo(condition: bool, b: u32) void {
    const a = if (condition) b else return;
    @panic("do something with a");
}
test "noreturn" {
    foo(false, 1);
}
``` ```
$ zig test test.zig
1/1 test "noreturn"...OK
All 1 tests passed.

Another use case for noreturn is the exit function:

test.zig

pub extern "kernel32" fn ExitProcess(exit_code: c_uint) callconv(.Stdcall) noreturn;

test "foo" {
    const value = bar() catch ExitProcess(1);
    assert(value == 1234);
}

fn bar() anyerror!u32 {
    return 1234;
}

const assert = @import("std").debug.assert;
``` ```
$ zig test test.zig -target x86_64-windows
Created /deps/zig/zig-cache/o/_I6hZMbZvC3tMTV1FwcUPpThS8tQ8yAAJ2aGq_TjkmaXTVCTeUUEG_vmnEaqFNAL/test.exe but skipping execution because it is non-native.