These rules are checked dynamically at runtime. The checking is
controlled by the cgocheck setting of the GODEBUG environment
variable. The default setting is GODEBUG=cgocheck=1, which implements
reasonably cheap dynamic checks. These checks may be disabled
entirely using GODEBUG=cgocheck=0. Complete checking of pointer
handling, at some cost in run time, is available by setting
GOEXPERIMENT=cgocheck2 at build time.

	// Second, if ContentErr==nil, the content should match Content.
	// If content is large, an alternative to setting Content is to set File,
	// which names a file in the testdata/ directory containing the
	// uncompressed expected content.
	// If content is very large, an alternative to setting Content or File
	// is to set Size, which will then be checked against the header-reported size

x[i], i = 2, 1  // set x[0] = 2, i = 1

x[0], x[0] = 1, 2  // set x[0] = 1, then x[0] = 2 (so x[0] == 2 at end)

x[1], x[3] = 4, 5  // set x[1] = 4, then panic setting x[3] = 5.

type Point struct { x, y int }
var p *Point
x[2], p.x = 6, 7  // set x[2] = 6, then panic setting p.x = 7

i = 2
x = []int{3, 5, 7}
for i, x[i] = range x {  // set i, x[2] = 0, x[0]
	break
}

If CC_FOR_TARGET is not set when the toolchain is built (make.bash or all.bash), CC
can be set on the command line. For example,

	GOOS=ios GOARCH=amd64 CGO_ENABLED=1 CC=$(go env GOROOT)/misc/ios/clangwrap.sh go build

Setting CC is not necessary if the toolchain is built with CC_FOR_TARGET set.

To use the go tool to run individual programs and tests, put $GOROOT/bin into PATH to ensure

The [`asynctimerchan` setting](/pkg/time/#NewTimer) disables this change.
There are no runtime metrics for this change,
This setting may be removed in a future release, Go 1.27 at the earliest.

Go 1.23 changed the mode bits reported by [`os.Lstat`](/pkg/os#Lstat) and [`os.Stat`](/pkg/os#Stat)
for reparse points, which can be controlled with the `winsymlink` setting.

pkg syscall (darwin-arm64), const SYS_SETSOCKOPT ideal-int
pkg syscall (darwin-arm64), const SYS_SETTID = 285
pkg syscall (darwin-arm64), const SYS_SETTID ideal-int
pkg syscall (darwin-arm64), const SYS_SETTID_WITH_PID = 311
pkg syscall (darwin-arm64), const SYS_SETTID_WITH_PID ideal-int
pkg syscall (darwin-arm64), const SYS_SETTIMEOFDAY = 122
pkg syscall (darwin-arm64), const SYS_SETTIMEOFDAY ideal-int

pkg syscall (darwin-386), const SYS_SETSID ideal-int
pkg syscall (darwin-386), const SYS_SETSOCKOPT ideal-int
pkg syscall (darwin-386), const SYS_SETTID ideal-int
pkg syscall (darwin-386), const SYS_SETTID_WITH_PID ideal-int
pkg syscall (darwin-386), const SYS_SETTIMEOFDAY ideal-int
pkg syscall (darwin-386), const SYS_SETUID ideal-int
pkg syscall (darwin-386), const SYS_SETWGROUPS ideal-int

	ctxt.Flag_maymorestack = flags.DebugFlags.MayMoreStack
	ctxt.Debugpcln = flags.DebugFlags.PCTab
	ctxt.IsAsm = true
	ctxt.Pkgpath = *flags.Importpath
	switch *flags.Spectre {
	default:
		log.Printf("unknown setting -spectre=%s", *flags.Spectre)
		os.Exit(2)
	case "":
		// nothing
	case "index":
		// known to compiler; ignore here so people can use
		// the same list with -gcflags=-spectre=LIST and -asmflags=-spectrre=LIST

		if r.Name.Kind == "func" {
			error_(r.Pos(), "must call C.%s", fixGo(r.Name.Go))
		}
	}
	return expr
}

// gofmtPos returns the gofmt-formatted string for an AST node,
// with a comment setting the position before the node.
func gofmtPos(n ast.Expr, pos token.Pos) string {
	s := gofmtLine(n)
	p := fset.Position(pos)
	if p.Column == 0 {
		return s
	}

		f.NonUTF8 = false
	default:
		// Might be UTF-8, might be some other encoding; preserve existing flag.
		// Some ZIP writers use UTF-8 encoding without setting the UTF-8 flag.
		// Since it is impossible to always distinguish valid UTF-8 from some
		// other encoding (e.g., GBK or Shift-JIS), we trust the flag.
		f.NonUTF8 = f.Flags&0x800 == 0
	}