### Iterators

The new [`iter` package](/pkg/iter/) provides the basic definitions for

Once the _cgo_export.c and *.cgo2.c files have been compiled with gcc,
they need to be linked into the final binary, along with the libraries
they might depend on (in the case of puts, stdio). cmd/link has been
extended to understand basic ELF files, but it does not understand ELF
in the full complexity that modern C libraries embrace, so it cannot
in general generate direct references to the system libraries.

// This input extends auto-generated amd64enc.s test suite
// with manually added tests.

#include "../../../../../runtime/textflag.h"

TEXT asmtest(SB),DUPOK|NOSPLIT,$0
	// AVX2GATHER: basic combinations.
	VPGATHERDQ Y2, (BP)(X7*2), Y1           // c4e2ed904c7d00
	VPGATHERDQ X12, (R13)(X14*2), X11       // c40299905c7500
	VPGATHERDQ Y12, (R13)(X14*2), Y11       // c4029d905c7500

			} else {
				paxHdrs[paxKey] = formatPAXTime(ts)
			}
		}
		if v, ok := h.PAXRecords[paxKey]; ok && v == formatPAXTime(ts) {
			paxHdrs[paxKey] = v
		}
	}

	// Check basic fields.
	var blk block
	v7 := blk.toV7()
	ustar := blk.toUSTAR()
	gnu := blk.toGNU()
	verifyString(h.Name, len(v7.name()), "Name", paxPath)
	verifyString(h.Linkname, len(v7.linkName()), "Linkname", paxLinkpath)

	needCSize := f.CompressedSize == ^uint32(0)
	needHeaderOffset := f.headerOffset == int64(^uint32(0))

	// Best effort to find what we need.
	// Other zip authors might not even follow the basic format,
	// and we'll just ignore the Extra content in that case.
	var modified time.Time
parseExtras:
	for extra := readBuf(f.Extra); len(extra) >= 4; { // need at least tag and size
		fieldTag := extra.uint16()

where a type element is a union of one or more <i>type terms</i>.
A type term is either a single type or a single underlying type.
</p>

<h4 id="Basic_interfaces">Basic interfaces</h4>

<p>
In its most basic form an interface specifies a (possibly empty) list of methods.
The type set defined by such an interface is the set of types which implement all of

			// Don't override old type
			if _, ok := typedef[name.Name]; ok {
				break
			}

			// Size calculation in c.Struct/c.Opaque will die with size=-1 (unknown),
			// so execute the basic things that the struct case would do
			// other than try to determine a Go representation.
			tt := *t
			tt.C = &TypeRepr{"%s %s", []interface{}{dt.Kind, tag}}

	SH3ADDUW	X16, X17			// bbe80821
	SLLIUW		$31, X17, X18			// 1b99f809
	SLLIUW		$63, X17			// 9b98f80b
	SLLIUW		$63, X17, X18			// 1b99f80b
	SLLIUW		$1, X18, X19			// 9b191908

	// 1.2: Basic Bit Manipulation (Zbb)
	ANDN	X19, X20, X21				// b37a3a41
	ANDN	X19, X20				// 337a3a41
	CLZ	X20, X21				// 931a0a60
	CLZW	X21, X22				// 1b9b0a60
	CPOP	X22, X23				// 931b2b60
	CPOPW	X23, X24				// 1b9c2b60

			}
			list = append(list, buf.String())
		}
	}
	sort.Strings(list)
	return list
}

func (w *Walker) writeType(buf *bytes.Buffer, typ types.Type) {
	switch typ := typ.(type) {
	case *types.Basic:
		s := typ.Name()
		switch typ.Kind() {
		case types.UnsafePointer:
			s = "unsafe.Pointer"
		case types.UntypedBool:
			s = "ideal-bool"
		case types.UntypedInt:
			s = "ideal-int"