pkg net, type DNSError struct, UnwrapErr error #63116

[TestFS] now returns a structured error that can be unwrapped
(via method `Unwrap() []error`). This allows inspecting errors

the <a href="#Numeric_types">unsigned integer</a>'s type.
Loosely speaking, these unsigned integer operations
discard high bits upon overflow, and programs may rely on "wrap around".
</p>
<p>
For signed integers, the operations <code>+</code>,
<code>-</code>, <code>*</code>, <code>/</code>, and <code>&lt;&lt;</code> may legally

	// to _cgoCheckPointer, as done in checkIndex and checkAddr.
	//
	// When the function argument is a conversion to unsafe.Pointer,
	// we unwrap the conversion before checking the pointer,
	// and then wrap again when calling C.f. This lets us check
	// the real type of the pointer in some cases. See issue #25941.
	//
	// When the call to C.f is deferred, we use an additional function

pkg os, method (*File) Readdir(int) ([]FileInfo, error)
pkg os, method (*File) Stat() (FileInfo, error)
pkg os, method (*PathError) Error() string
pkg os, method (*PathError) Timeout() bool
pkg os, method (*PathError) Unwrap() error
pkg os, method (FileMode) IsDir() bool
pkg os, method (FileMode) IsRegular() bool
pkg os, method (FileMode) Perm() FileMode
pkg os, method (FileMode) String() string

is the name <code>foo</code> as an address in memory.
This form is used to name global functions and data.
Adding <code>&lt;&gt;</code> to the name, as in <span style="white-space: nowrap"><code>foo&lt;&gt;(SB)</code></span>, makes the name
visible only in the current source file, like a top-level <code>static</code> declaration in a C file.

computed modulo 2<sup><i>n</i></sup>, where <i>n</i> is the bit width of
the unsigned integer's type.
Loosely speaking, these unsigned integer operations
discard high bits upon overflow, and programs may rely on "wrap around".
</p>

<p>
For signed integers, the operations <code>+</code>,
<code>-</code>, <code>*</code>, <code>/</code>, and <code>&lt;&lt;</code> may legally