Merge remote-tracking branch 'upstream/master' into 41884-fix

Author: ncruces

doc/asm.html

@@ -464,6 +464,57 @@ <h3 id="directives">Directives</h3>
 </li>
 </ul>
 
+<h3 id="data-offsets">Interacting with Go types and constants</h3>
+
+<p>
+If a package has any .s files, then <code>go build</code> will direct
+the compiler to emit a special header called <code>go_asm.h</code>,
+which the .s files can then <code>#include</code>.
+The file contains symbolic <code>#define</code> constants for the
+offsets of Go struct fields, the sizes of Go struct types, and most
+Go <code>const</code> declarations defined in the current package.
+Go assembly should avoid making assumptions about the layout of Go
+types and instead use these constants.
+This improves the readability of assembly code, and keeps it robust to
+changes in data layout either in the Go type definitions or in the
+layout rules used by the Go compiler.
+</p>
+
+<p>
+Constants are of the form <code>const_<i>name</i></code>.
+For example, given the Go declaration <code>const bufSize =
+1024</code>, assembly code can refer to the value of this constant
+as <code>const_bufSize</code>.
+</p>
+
+<p>
+Field offsets are of the form <code><i>type</i>_<i>field</i></code>.
+Struct sizes are of the form <code><i>type</i>__size</code>.
+For example, consider the following Go definition:
+</p>
+
+<pre>
+type reader struct {
+	buf [bufSize]byte
+	r   int
+}
+</pre>
+
+<p>
+Assembly can refer to the size of this struct
+as <code>reader__size</code> and the offsets of the two fields
+as <code>reader_buf</code> and <code>reader_r</code>.
+Hence, if register <code>R1</code> contains a pointer to
+a <code>reader</code>, assembly can reference the <code>r</code> field
+as <code>reader_r(R1)</code>.
+</p>
+
+<p>
+If any of these <code>#define</code> names are ambiguous (for example,
+a struct with a <code>_size</code> field), <code>#include
+"go_asm.h"</code> will fail with a "redefinition of macro" error.
+</p>
+
 <h3 id="runtime">Runtime Coordination</h3>
 
 <p>
@@ -615,21 +666,15 @@ <h3 id="x86">32-bit Intel 386</h3>
 <p>
 The runtime pointer to the <code>g</code> structure is maintained
 through the value of an otherwise unused (as far as Go is concerned) register in the MMU.
-An OS-dependent macro <code>get_tls</code> is defined for the assembler if the source is
-in the <code>runtime</code> package and includes a special header, <code>go_tls.h</code>:
+In the runtime package, assembly code can include <code>go_tls.h</code>, which defines
+an OS- and architecture-dependent macro <code>get_tls</code> for accessing this register.
+The <code>get_tls</code> macro takes one argument, which is the register to load the
+<code>g</code> pointer into.
 </p>
 
-<pre>
-#include "go_tls.h"
-</pre>
-
 <p>
-Within the runtime, the <code>get_tls</code> macro loads its argument register
-with a pointer to the <code>g</code> pointer, and the <code>g</code> struct
-contains the <code>m</code> pointer.
-There's another special header containing the offsets for each
-element of <code>g</code>, called <code>go_asm.h</code>.
-The sequence to load <code>g</code> and <code>m</code> using <code>CX</code> looks like this:
+For example, the sequence to load <code>g</code> and <code>m</code>
+using <code>CX</code> looks like this:
 </p>
 
 <pre>
@@ -642,8 +687,7 @@ <h3 id="x86">32-bit Intel 386</h3>
 </pre>
 
 <p>
-Note: The code above works only in the <code>runtime</code> package, while <code>go_tls.h</code> also
-applies to <a href="#arm">arm</a>, <a href="#amd64">amd64</a> and amd64p32, and <code>go_asm.h</code> applies to all architectures.
+The <code>get_tls</code> macro is also defined on <a href="#amd64">amd64</a>.
 </p>
 
 <p>

doc/go1.16.html

@@ -275,7 +275,7 @@ <h4 id="list-buildid">The <code>list</code> command</h4>
   When the <code>-export</code> flag is specified, the <code>BuildID</code>
   field is now set to the build ID of the compiled package. This is equivalent
   to running <code>go</code> <code>tool</code> <code>buildid</code> on
-  <code>go</code> <code>list</code> <code>-exported</code> <code>-f</code> <code>{{.Export}</code>,
+  <code>go</code> <code>list</code> <code>-exported</code> <code>-f</code> <code>{{.Export}}</code>,
   but without the extra step.
 </p>
 
@@ -461,10 +461,10 @@ <h3 id="fs">File Systems</h3>
 
 <p>
   The new <a href="/pkg/io/fs/"><code>io/fs</code></a> package
-  defines an abstraction for read-only trees of files,
-  the <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a> interface,
-  and the standard library packages have
-  been adapted to make use of the interface as appropriate.
+  defines the <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a> interface,
+  an abstraction for read-only trees of files.
+  The standard library packages have been adapted to make use
+  of the interface as appropriate.
 </p>
 
 <p>
@@ -499,6 +499,44 @@ <h3 id="fs">File Systems</h3>
   implementations.
 </p>
 
+<h3 id="ioutil">Deprecation of io/ioutil</h3>
+
+<p>
+  The <a href="/pkg/io/ioutil/"><code>io/ioutil</code></a> package has
+  turned out to be a poorly defined and hard to understand collection
+  of things. All functionality provided by the package has been moved
+  to other packages. The <code>io/ioutil</code> package remains and
+  will continue to work as before, but we encourage new code to use
+  the new definitions in the <a href="/pkg/io/"><code>io</code></a> and
+  <a href="/pkg/os/"><code>os</code></a> packages.
+
+  Here is a list of the new locations of the names exported
+  by <code>io/ioutil</code>:
+  <ul>
+    <li><a href="/pkg/io/ioutil/#Discard"><code>Discard</code></a>
+      => <a href="/pkg/io/#Discard"><code>io.Discard</code></a></li>
+    <li><a href="/pkg/io/ioutil/#NopCloser"><code>NopCloser</code></a>
+      => <a href="/pkg/io/#NopCloser"><code>io.NopCloser</code></a></li>
+    <li><a href="/pkg/io/ioutil/#ReadAll"><code>ReadAll</code></a>
+      => <a href="/pkg/io/#ReadAll"><code>io.ReadAll</code></a></li>
+    <li><a href="/pkg/io/ioutil/#ReadDir"><code>ReadDir</code></a>
+      => <a href="/pkg/os/#ReadDir"><code>os.ReadDir</code></a>
+      (note: returns a slice of
+      <a href="/pkg/os/#DirEntry"><code>os.DirEntry</code></a>
+      rather than a slice of
+      <a href="/pkg/fs/#FileInfo"><code>fs.FileInfo</code></a>)
+    </li>
+    <li><a href="/pkg/io/ioutil/#ReadFile"><code>ReadFile</code></a>
+      => <a href="/pkg/os/#ReadFile"><code>os.ReadFile</code></a></li>
+    <li><a href="/pkg/io/ioutil/#TempDir"><code>TempDir</code></a>
+      => <a href="/pkg/os/#MkdirTemp"><code>os.MkdirTemp</code></a></li>
+    <li><a href="/pkg/io/ioutil/#TempFile"><code>TempFile</code></a>
+      => <a href="/pkg/os/#CreateTemp"><code>os.CreateTemp</code></a></li>
+    <li><a href="/pkg/io/ioutil/#WriteFile"><code>WriteFile</code></a>
+      => <a href="/pkg/os/#WriteFile"><code>os.WriteFile</code></a></li>
+  </ul>
+</p>
+
 <!-- okay-after-beta1
   TODO: decide if any additional changes are worth factoring out from
   "Minor changes to the library" and highlighting in "Core library"
@@ -623,6 +661,14 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
       method allows accessing the <a href="/pkg/crypto/x509/#SystemRootsError.Err"><code>Err</code></a>
       field through the <a href="/pkg/errors"><code>errors</code></a> package functions.
     </p>
+
+    <p><!-- CL 230025 -->
+      On Unix systems, the <code>crypto/x509</code> package is now more
+      efficient in how it stores its copy of the system cert pool.
+      Programs that use only a small number of roots will use around a
+      half megabyte less memory.
+    </p>
+
   </dd>
 </dl><!-- crypto/x509 -->
 
@@ -685,6 +731,37 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
   </dd>
 </dl><!-- flag -->
 
+<dl id="go/build"><dt><a href="/pkg/go/build/">go/build</a></dt>
+  <dd>
+    <p><!-- CL 243941, CL 283636 -->
+      The <a href="/pkg/go/build/#Package"><code>Package</code></a>
+      struct has new fields that report information
+      about <code>//go:embed</code> directives in the package:
+      <a href="/pkg/go/build/#Package.EmbedPatterns"><code>EmbedPatterns</code></a>,
+      <a href="/pkg/go/build/#Package.EmbedPatternPos"><code>EmbedPatternPos</code></a>,
+      <a href="/pkg/go/build/#Package.TestEmbedPatterns"><code>TestEmbedPatterns</code></a>,
+      <a href="/pkg/go/build/#Package.TestEmbedPatternPos"><code>TestEmbedPatternPos</code></a>,
+      <a href="/pkg/go/build/#Package.XTestEmbedPatterns"><code>XTestEmbedPatterns</code></a>,
+      <a href="/pkg/go/build/#Package.XTestEmbedPatternPos"><code>XTestEmbedPatternPos</code></a>.
+    </p>
+
+    <p><!-- CL 240551 -->
+      The <a href="/pkg/go/build/#Package"><code>Package</code></a> field
+      <a href="/pkg/go/build/#Package.IgnoredGoFiles"><code>IgnoredGoFiles</code></a>
+      will no longer include files that start with "_" or ".",
+      as those files are always ignored.
+      <code>IgnoredGoFiles</code> is for files ignored because of
+      build constraints.
+    </p>
+
+    <p><!-- CL 240551 -->
+      The new <a href="/pkg/go/build/#Package"><code>Package</code></a>
+      field <a href="/pkg/go/build/#Package.IgnoredOtherFiles"><code>IgnoredOtherFiles</code></a>
+      has a list of non-Go files ignored because of build constraints.
+    </p>
+  </dd>
+</dl><!-- go/build -->
+
 <dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt>
   <dd>
     <p><!-- CL 243938 -->
@@ -703,6 +780,15 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
       The package now defines a
       <a href="/pkg/io/#ReadSeekCloser"><code>ReadSeekCloser</code></a> interface.
     </p>
+
+    <p><!-- CL 263141 -->
+      The package now defines
+      <a href="/pkg/io/#Discard"><code>Discard</code></a>,
+      <a href="/pkg/io/#NopCloser"><code>NopCloser</code></a>, and
+      <a href="/pkg/io/#ReadAll"><code>ReadAll</code></a>,
+      to be used instead of the same names in the
+      <a href="/pkg/io/ioutil/"><code>io/ioutil</code></a> package.
+    </p>
   </dd>
 </dl><!-- io -->
 
@@ -857,6 +943,52 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
       instead of the unexported <code>errFinished</code> when the process has
       already finished.
     </p>
+
+    <p><!-- CL 261540 -->
+      The package defines a new type
+      <a href="/pkg/os/#DirEntry"><code>DirEntry</code></a>
+      as an alias for <a href="/pkg/io/fs/#DirEntry"><code>fs.DirEntry</code></a>.
+      The new <a href="/pkg/os/#ReadDir"><code>ReadDir</code></a>
+      function and the new
+      <a href="/pkg/os/#File.ReadDir"><code>File.ReadDir</code></a>
+      method can be used to read the contents of a directory into a
+      slice of <a href="/pkg/os/#DirEntry"><code>DirEntry</code></a>.
+      The <a href="/pkg/os/#File.Readdir"><code>File.Readdir</code></a>
+      method (note the lower case <code>d</code> in <code>dir</code>)
+      still exists, returning a slice of
+      <a href="/pkg/os/#FileInfo"><code>FileInfo</code></a>, but for
+      most programs it will be more efficient to switch to
+      <a href="/pkg/os/#File.ReadDir"><code>File.ReadDir</code></a>.
+    </p>
+
+    <p><!-- CL 263141 -->
+      The package now defines
+      <a href="/pkg/os/#CreateTemp"><code>CreateTemp</code></a>,
+      <a href="/pkg/os/#MkdirTemp"><code>MkdirTemp</code></a>,
+      <a href="/pkg/os/#ReadFile"><code>ReadFile</code></a>, and
+      <a href="/pkg/os/#WriteFile"><code>WriteFile</code></a>,
+      to be used instead of functions defined in the
+      <a href="/pkg/io/ioutil/"><code>io/ioutil</code></a> package.
+    </p>
+
+    <p><!-- CL 243906 -->
+      The types <a href="/pkg/os/#FileInfo"><code>FileInfo</code></a>,
+      <a href="/pkg/os/#FileMode"><code>FileMode</code></a>, and
+      <a href="/pkg/os/#PathError"><code>PathError</code></a>
+      are now aliases for types of the same name in the
+      <a href="/pkg/io/fs/"><code>io/fs</code></a> package.
+      Function signatures in the <a href="/pkg/os/"><code>os</code></a>
+      package have been updated to refer to the names in the
+      <a href="/pkg/io/fs/"><code>io/fs</code></a> package.
+      This should not affect any existing code.
+    </p>
+
+    <p><!-- CL 243911 -->
+      The new <a href="/pkg/os/#DirFS"><code>DirFS</code></a> function
+      provides an implementation of
+      <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a> backed by a tree
+      of operating system files.
+    </p>
   </dd>
 </dl><!-- os -->
 
@@ -887,9 +1019,9 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
   <dd>
     <p><!-- CL 267887 -->
       The new function
-      <a href="/pkg/path/filepath/WalkDir"><code>WalkDir</code></a>
+      <a href="/pkg/path/filepath/#WalkDir"><code>WalkDir</code></a>
       is similar to
-      <a href="/pkg/path/filepath/Walk"><code>Walk</code></a>,
+      <a href="/pkg/path/filepath/#Walk"><code>Walk</code></a>,
       but is typically more efficient.
       The function passed to <code>WalkDir</code> receives a
       <a href="/pkg/io/fs/#DirEntry"><code>fs.DirEntry</code></a>
@@ -975,6 +1107,25 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
   </dd>
 </dl><!-- syscall -->
 
+<dl id="testing/iotest"><dt><a href="/pkg/testing/iotest/">testing/iotest</a></dt>
+  <dd>
+    <p><!-- CL 199501 -->
+      The new
+      <a href="/pkg/testing/iotest/#ErrReader"><code>ErrReader</code></a>
+      function returns an
+      <a href="/pkg/io/#Reader"><code>io.Reader</code></a> that always
+      returns an error.
+    </p>
+
+    <p><!-- CL 243909 -->
+      The new
+      <a href="/pkg/testing/iotest/#TestReader"><code>TestReader</code></a>
+      function tests that an <a href="/pkg/io/#Reader"><code>io.Reader</code></a>
+      behaves correctly.
+    </p>
+  </dd>
+</dl><!-- testing/iotest -->
+
 <dl id="text/template"><dt><a href="/pkg/text/template/">text/template</a></dt>
   <dd>
     <p><!-- CL 254257, golang.org/issue/29770 -->

lib/time/update.bash

@@ -8,8 +8,8 @@
 # Consult https://www.iana.org/time-zones for the latest versions.
 
 # Versions to use.
-CODE=2020f
-DATA=2020f
+CODE=2021a
+DATA=2021a
 
 set -e
 rm -rf work

lib/time/zoneinfo.zip

@@ -267,7 +267,7 @@ func walkstmt(n *Node) *Node {
 		if n.List.Len() == 0 {
 			break
 		}
-		if (Curfn.Type.FuncType().Outnamed && n.List.Len() > 1) || paramoutheap(Curfn) {
+		if (Curfn.Type.FuncType().Outnamed && n.List.Len() > 1) || paramoutheap(Curfn) || Curfn.Func.HasDefer() {
 			// assign to the function out parameters,
 			// so that reorder3 can fix up conflicts
 			var rl []*Node
@@ -2233,7 +2233,15 @@ func aliased(r *Node, all []*Node) bool {
 			memwrite = true
 			continue
 
-		case PAUTO, PPARAM, PPARAMOUT:
+		case PPARAMOUT:
+			// Assignments to a result parameter in a function with defers
+			// becomes visible early if evaluation of any later expression
+			// panics (#43835).
+			if Curfn.Func.HasDefer() {
+				return true
+			}
+			fallthrough
+		case PAUTO, PPARAM:
 			if l.Name.Addrtaken() {
 				memwrite = true
 				continue

src/cmd/compile/internal/gc/walk.go

@@ -1,5 +1,12 @@
 [!cgo] skip
 
+# Set CC explicitly to something that requires a PATH lookup.
+# Normally, the default is gcc or clang, but if CC was set during make.bash,
+# that becomes the default.
+[exec:clang] env CC=clang
+[exec:gcc] env CC=gcc
+[!exec:clang] [!exec:gcc] skip 'Unknown C compiler'
+
 env GOCACHE=$WORK/gocache  # Looking for compile flags, so need a clean cache.
 [!windows] env PATH=.:$PATH
 [!windows] chmod 0755 p/gcc p/clang