handling, at some cost in run time, is available by setting
GOEXPERIMENT=cgocheck2 at build time.

It is possible to defeat this enforcement by using the unsafe package,
and of course there is nothing stopping the C code from doing anything
it likes. However, programs that break these rules are likely to fail
in unexpected and unpredictable ways.

The runtime/cgo.Handle type can be used to safely pass Go values

For the remaining programs,
we define a new GODEBUG setting that
allows individual programs to opt back in to the old behavior.
A GODEBUG setting may not be added if doing so is infeasible,
but that should be extremely rare.

GODEBUG settings added for compatibility will be maintained
for a minimum of two years (four Go releases).
Some, such as `http2client` and `http2server`,

	if x, ok := x.(*ast.Ident); ok {
		if f.isMangledName(x.Name) {
			error_(x.Pos(), "identifier %q may conflict with identifiers generated by cgo", x.Name)
		}
	}
}

// Save various references we are going to need later.
func (f *File) saveExprs(x interface{}, context astContext) {
	switch x := x.(type) {
	case *ast.Expr:
		switch (*x).(type) {
		case *ast.SelectorExpr:
			f.saveRef(x, context)
		}

		err:  ErrHeader,
	}, {
		// BSD tar v3.1.2 rejects a PAX path with NUL in the value, while
		// GNU tar v1.27.1 simply truncates at first NUL.
		// We emulate the behavior of BSD since it is strange doing NUL
		// truncations since PAX records are length-prefix strings instead
		// of NUL-terminated C-strings.
		file: "testdata/pax-nul-path.tar",
		err:  ErrHeader,
	}, {
		file: "testdata/neg-size.tar",

It implements these forms as multiple instructions, often using the <code>R11</code> register
to hold temporary values.
Hand-written assembly can use <code>R11</code>, but doing so requires
being sure that the linker is not also using it to implement any of the other
instructions in the function.
</p>

<p>
When defining a <code>TEXT</code>, specifying frame size <code>$-4</code>

	// The start index is inclusive and the end index is exclusive.
	type span struct {
		start int
		end   int
	}
	spans := make([]span, 0, 32)

	// Find the field start and end indices.
	// Doing this in a separate pass (rather than slicing the string s
	// and collecting the result substrings right away) is significantly
	// more efficient, possibly due to cache effects.
	start := -1 // valid span start if >= 0

			if err != nil {
				log.Fatalf("go list: invalid output: %v", err)
			}

			// - Package "unsafe" contains special signatures requiring
			//   extra care when printing them - ignore since it is not
			//   going to change w/o a language change.
			// - Internal and vendored packages do not contribute to our
			//   API surface. (If we are running within the "std" module,
			//   vendored dependencies appear as themselves instead of