//
// Scanning stops if the function returns an error, in which case some of
// the input may be discarded. If that error is [ErrFinalToken], scanning
// stops with no error. A non-nil token delivered with [ErrFinalToken]
// will be the last token, and a nil token with [ErrFinalToken]
// immediately stops the scanning.
//
// Otherwise, the [Scanner] advances the input. If the token is not nil,

	for scanner.Scan() {
		fmt.Println(len(scanner.Bytes()) == 6)
	}
	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "shouldn't see an error scanning a string")
	}
	// Output:
	// true
}

// Use a Scanner to implement a simple word-count utility by scanning the
// input as a sequence of space-delimited tokens.
func ExampleScanner_words() {
	// An artificial input source.

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "_cgo_export.h"

/* Test calling a Go function with multiple return values.  */

void
callMulti(void)
{
	struct multi_return result = multi();
	assert(strcmp(result.r0, "multi") == 0);
	assert(result.r1 == 0);
	free(result.r0);

type ReadCloser struct {
	f *os.File
	Reader
}

// A File is a single file in a ZIP archive.
// The file information is in the embedded [FileHeader].
// The file content can be accessed by calling [File.Open].
type File struct {
	FileHeader
	zip          *Reader
	zipr         io.ReaderAt
	headerOffset int64 // includes overall ZIP archive baseOffset

<p>
The <code>PCALIGN</code> pseudo-instruction is used to indicate that the next instruction should be aligned
to a specified boundary by padding with no-op instructions.
</p>

<p>
It is currently supported on arm64, amd64, ppc64, loong64 and riscv64.

For example, the start of the <code>MOVD</code> instruction below is aligned to 32 bytes:
<pre>
PCALIGN $32
MOVD $2, R0
</pre>
</p>

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build gc

#include "_cgo_export.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

/* Test calling panic from C.  This is what SWIG does.  */

extern void crosscall2(void (*fn)(void *, int), void *, int);
extern void _cgo_panic(void *, int);
extern void _cgo_allocate(void *, int);

void
callPanic(void)
{

	sel := (*n).(*ast.SelectorExpr)
	// For now, assume that the only instance of capital C is when
	// used as the imported package identifier.
	// The parser should take care of scoping in the future, so
	// that we will be able to distinguish a "top-level C" from a
	// local C.
	if l, ok := sel.X.(*ast.Ident); !ok || l.Name != "C" {
		return
	}
	if context == ctxAssign2 {
		context = ctxExpr

				p.errorf("unimplemented two-register form")
			}
			a.Index = r1
			if scale != 0 && scale != 1 && (p.arch.Family == sys.ARM64 ||
				p.arch.Family == sys.PPC64) {
				// Support (R1)(R2) (no scaling) and (R1)(R2*1).
				p.errorf("%s doesn't support scaled register format", p.arch.Name)
			} else {
				a.Scale = int16(scale)
			}
		}
		p.get(')')
	} else if scale != 0 {

In C, a function argument written as a fixed size array
actually requires a pointer to the first element of the array.
C compilers are aware of this calling convention and adjust
the call accordingly, but Go cannot. In Go, you must pass
the pointer to the first element explicitly: C.f(&C.x[0]).

Calling variadic C functions is not supported. It is possible to
circumvent this by using a C function wrapper. For example:

	package main

//go:linkname runtime_arena_newArena
func runtime_arena_newArena() unsafe.Pointer

//go:linkname runtime_arena_arena_New
func runtime_arena_arena_New(arena unsafe.Pointer, typ any) any

// Mark as noescape to avoid escaping the slice header.
//
//go:noescape
//go:linkname runtime_arena_arena_Slice
func runtime_arena_arena_Slice(arena unsafe.Pointer, slice any, cap int)

//go:linkname runtime_arena_arena_Free