<pre class="grammar">
"var" IdentifierList = ExpressionList .
</pre>

<pre>
i, j := 0, 10
f := func() int { return 7 }
ch := make(chan int)
r, w, _ := os.Pipe()  // os.Pipe() returns a connected pair of Files and an error, if any
_, y, _ := coord(p)   // coord() returns three values; only interested in y coordinate
</pre>

<p>
Unlike regular variable declarations, a short variable declaration may <i>redeclare</i>

		nsecs = -(nsecs - 1e9) // Take that second away from nsecs
	}
	return strings.TrimRight(fmt.Sprintf("%s%d.%09d", sign, secs, nsecs), "0")
}

// parsePAXRecord parses the input PAX record string into a key-value pair.
// If parsing is successful, it will slice off the currently read record and
// return the remainder as r.
func parsePAXRecord(s string) (k, v, r string, err error) {
	// The size field ends at the first space.

	MRS	ID_PFR1_EL1, R12                   // 2c0138d5
	MRS	ISR_EL1, R24                       // 18c138d5
	MRS	MAIR_EL1, R20                      // 14a238d5
	MSR	R21, MAIR_EL1                      // 15a218d5
	MRS	MAIR_EL1, R20                      // 14a238d5
	MSR	R5, MAIR_EL1                       // 05a218d5
	MRS	MDCCINT_EL1, R23                   // 170230d5
	MSR	R27, MDCCINT_EL1                   // 1b0210d5

Even so, Go provides a mechanism called GODEBUG to
reduce the impact such changes have on Go developers
using newer toolchains to compile old code.

A GODEBUG setting is a `key=value` pair
that controls the execution of certain parts of a Go program.
The environment variable `GODEBUG`
can hold a comma-separated list of these settings.
For example, if a Go program is running in an environment that contains

		if p.arch.InFamily(sys.ARM, sys.ARM64) {
			// Special form
			// ARM: destination register pair (R1, R2).
			// ARM64: register pair (R1, R2) for LDP/STP.
			if prefix != 0 || scale != 0 {
				p.errorf("illegal address mode for register pair")
				return
			}
			a.Type = obj.TYPE_REGREG
			a.Offset = int64(r2)
			// Nothing may follow
			return
		}

<code>[R0,g,R12-R15]</code>: For multi-register instructions, the set comprising
<code>R0</code>, <code>g</code>, and <code>R12</code> through <code>R15</code> inclusive.
</li>

<li>
<code>(R5, R6)</code>: Destination register pair.
</li>

</ul>

<h3 id="arm64">ARM64</h3>

<p>
<code>R18</code> is the "platform register", reserved on the Apple platform.
To prevent accidental misuse, the register is named <code>R18_PLATFORM</code>.

		{"☻x\xe2\x98x", '�', len("☻x")},

		// Invalid rune values should never match.
		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", -1, -1},
		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", 0xD800, -1}, // Surrogate pair
		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", utf8.MaxRune + 1, -1},
	}
	for _, tt := range tests {
		if got := IndexRune([]byte(tt.in), tt.rune); got != tt.want {

corresponding type parameters have corresponding constraints.
</p>

<pre>
type Pair[A, B any] struct {
	a A
	b B
}

func (p Pair[A, B]) Swap() Pair[B, A]  { … }  // receiver declares A, B
func (p Pair[First, _]) First() First  { … }  // receiver declares First, corresponds to A in Pair
</pre>

<h2 id="Expressions">Expressions</h2>

<p>

pkg p4, func NewPair[$0 interface{ M }, $1 interface{ ~int }]($0, $1) Pair[$0, $1]
pkg p4, method (Pair[$0, $1]) Second() $1
pkg p4, method (Pair[$0, $1]) First() $0
pkg p4, type Pair[$0 interface{ M }, $1 interface{ ~int }] struct
pkg p4, func Clone[$0 interface{ ~[]$1 }, $1 interface{}]($0) $0

		return true
	}
	return false
}

// IsARM64CASP reports whether the op (as defined by an arm64.A*
// constant) is one of the CASP-like instructions, and its 2nd
// destination is a register pair that require special handling.
func IsARM64CASP(op obj.As) bool {
	switch op {
	case arm64.ACASPD, arm64.ACASPW:
		return true
	}
	return false
}