The new type [KeepAliveConfig] permits fine-tuning the keep-alive
options for TCP connections, via a new [TCPConn.SetKeepAliveConfig]

func Map(mapping func(r rune) rune, s []byte) []byte {
	// In the worst case, the slice can grow when mapped, making
	// things unpleasant. But it's so rare we barge in assuming it's
	// fine. It could also shrink but that falls out naturally.
	b := make([]byte, 0, len(s))
	for i := 0; i < len(s); {
		wid := 1
		r := rune(s[i])
		if r >= utf8.RuneSelf {
			r, wid = utf8.DecodeRune(s[i:])
		}

Matthew Dempsky <******@****.***> 1693101993 -0700

		}
	}
	in.Push(NewTokenizer(name, fd, fd))
}

// #line processing.
func (in *Input) line() {
	// Only need to handle Plan 9 format: #line 337 "filename"
	tok := in.Stack.Next()
	if tok != scanner.Int {
		in.expectText("expected line number after #line")
	}
	line, err := strconv.Atoi(in.Stack.Text())
	if err != nil {
		in.Error("error parsing #line (cannot happen):", err)
	}
	tok = in.Stack.Next()

	var files []string
	for _, line := range lines {
		if len(line) == 0 {
			continue
		}
		xmlLines := getLines(parseMobileProvision(string(line)))
		matches := 0
		for _, udid := range udids {
			for _, xmlLine := range xmlLines {
				if bytes.Contains(xmlLine, udid) {
					matches++
				}
			}
		}
		if matches == len(udids) {
			files = append(files, string(line))
		}
	}
	return files
}

Each file is a list of API features, one per line.

go1.txt (and similarly named files) are frozen once a version has been
shipped. Each file adds new lines but does not remove any.

except.txt lists features that may disappear without breaking true
compatibility.

Starting with go1.19.txt, each API feature line must end in "#nnnnn"
giving the GitHub issue number of the proposal issue that accepted

	JCS	2(PC)
	JMP	*4(SP) // JMP 4(SP)
	JCS	2(PC)
	JMP	*(R12) // JMP (R12)
	JCS	2(PC)
//	JMP	*(R12*4) // TODO: This line is silently dropped on the floor!
	JCS	2(PC)
	JMP	*(R12)(R13*4) // JMP (R12)(R13*4)
	JCS	2(PC)
	JMP	*(AX) // JMP (AX)
	JCS	2(PC)
	JMP	*(SP) // JMP (SP)
	JCS	2(PC)
//	JMP	*(AX*4) // TODO: This line is silently dropped on the floor!
	JCS	2(PC)
	JMP	*(AX)(AX*4) // JMP (AX)(AX*4)
	JCS	2(PC)
	JMP	4(SP)
	JCS	2(PC)

		}
		return tok
	}
}

// line consumes a single assembly line from p.lex of the form
//
//	{label:} WORD[.cond] [ arg {, arg} ] (';' | '\n')
//
// It adds any labels to p.pendingLabels and returns the word, cond,
// operand list, and true. If there is an error or EOF, it returns
// ok=false.
//
// line may reuse the memory from scratch.

<p>
Given the declarations
</p>
<pre>
type Point3D struct { x, y, z float64 }
type Line struct { p, q Point3D }
</pre>

<p>
one may write
</p>

<pre>
origin := Point3D{}                            // zero value for Point3D
line := Line{origin, Point3D{y: -4, z: 12.3}}  // zero value for line.q.x
</pre>

<p>
For array and slice literals the following rules apply:
</p>
<ul>

poll the length to decide whether a receive on the timer channel
will succeed.
Such code should use a non-blocking receive instead.

These new behaviors are only enabled when the main Go program
is in a module with a `go.mod` `go` line using Go 1.23.0 or later.
When Go 1.23 builds older programs, the old behaviors remain in effect.
The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)