t.Fatalf("addr2line_test.go and %s are not same file", srcPath)
	}
	if want := "124"; srcLineNo != want {
		t.Fatalf("line number = %v; want %s", srcLineNo, want)
	}
}

// This is line 123. The test depends on that.
func TestAddr2Line(t *testing.T) {
	testenv.MustHaveGoBuild(t)

	tmpDir, err := os.MkdirTemp("", "TestAddr2Line")
	if err != nil {
		t.Fatal("TempDir failed: ", err)
	}
	defer os.RemoveAll(tmpDir)

	CompressedSize64 uint64

	// UncompressedSize64 is the uncompressed size of the file in bytes.
	UncompressedSize64 uint64

	Extra         []byte
	ExternalAttrs uint32 // Meaning depends on CreatorVersion
}

// FileInfo returns an fs.FileInfo for the [FileHeader].
func (h *FileHeader) FileInfo() fs.FileInfo {
	return headerFileInfo{h}
}

// headerFileInfo implements [fs.FileInfo].

	void
	_cgo_gcc_Cfunc_sin(void *v)
	{
		struct {
			double p0;
			double r;
		} __attribute__((__packed__)) *a = v;
		a->r = sin(a->p0);
	}

What happens at link time depends on whether the final binary is linked
using the internal or external mode. If other packages are compiled in
"external only" mode, then the final link will be an external one.
Otherwise the link will be an internal one.

which are tied to a specific release.
-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.
If code depends on buggy (including insecure) behavior,
then fixing the bug will break that code.
New features can also have similar impacts:
enabling the HTTP/2 use by the HTTP client broke programs

<code>t.m</code> is invoked.
</li>

<li>
A variable, function, or method <code>x</code> depends on a variable
<code>y</code> if <code>x</code>'s initialization expression or body
(for functions and methods) contains a reference to <code>y</code>
or to a function or method that depends on <code>y</code>.
</li>
</ul>

<p>
For example, given the declarations
</p>

<pre>

// slice, map, or chan (only). Like new, the first argument is a type, not a
// value. Unlike new, make's return type is the same as the type of its
// argument, not a pointer to it. The specification of the result depends on
// the type:
//
//	Slice: The size specifies the length. The capacity of the slice is
//	equal to its length. A second integer argument may be provided to

high bit is set is rejected.
</p>

<h3 id="symbols">Symbols</h3>

<p>
Some symbols, such as <code>R1</code> or <code>LR</code>,
are predefined and refer to registers.
The exact set depends on the architecture.
</p>

<p>
There are four predeclared symbols that refer to pseudo-registers.
These are not real registers, but rather virtual registers maintained by
the toolchain, such as a frame pointer.

// punctuation properly. Use golang.org/x/text/cases instead.
func Title(s []byte) []byte {
	// Use a closure here to remember state.
	// Hackish but effective. Depends on Map scanning in order and calling
	// the closure once per rune.
	prev := ' '
	return Map(
		func(r rune) rune {
			if isSeparator(prev) {
				prev = r
				return unicode.ToTitle(r)
			}

		// See golang.org/issue/6563.
		pos := (*r.Expr).Pos()
		if x, ok := expr.(*ast.Ident); ok {
			expr = &ast.Ident{NamePos: pos, Name: x.Name}
		}

		// Change AST, because some later processing depends on it,
		// and also because -godefs mode still prints the AST.
		old := *r.Expr
		*r.Expr = expr

		// Record source-level edit for cgo output.
		if !r.Done {

//	w.importDir["vendor/golang.org/x/net/route"] = "<goroot>/src/vendor/golang.org/x/net/route"
//
// Since the set of packages that exist depends on context, the result of
// loadImports also depends on context. However, to improve test running time
// the configuration for each environment is cached across runs.
func (w *Walker) loadImports() {
	if w.context == nil {