Merge "[dev.cmdgo] all: merge master (9eee0ed) into dev.cmdgo" into dev.cmdgo

api/go1.17.txt

@@ -80,6 +80,7 @@ pkg net/url, method (Values) Has(string) bool
 pkg reflect, func VisibleFields(Type) []StructField
 pkg reflect, method (Method) IsExported() bool
 pkg reflect, method (StructField) IsExported() bool
+pkg reflect, method (Value) CanConvert(Type) bool
 pkg runtime/cgo (darwin-amd64-cgo), func NewHandle(interface{}) Handle
 pkg runtime/cgo (darwin-amd64-cgo), method (Handle) Delete()
 pkg runtime/cgo (darwin-amd64-cgo), method (Handle) Value() interface{}

doc/asm.html

@@ -827,10 +827,6 @@ The other codes are <code>-&gt;</code> (arithmetic right shift),
 
 <h3 id="arm64">ARM64</h3>
 
-<p>
-The ARM64 port is in an experimental state.
-</p>
-
 <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>.

doc/go1.17.html

@@ -119,6 +119,17 @@ Do not send CLs removing the interior tags from such phrases.
   stack frame pointers only on Linux, macOS, and iOS.
 </p>
 
+<h3 id="loong64">loong64 GOARCH value reserved</h3>
+
+<p><!-- CL 333909 -->
+  The main Go compiler does not yet support the LoongArch
+  architecture, but we've reserved the <code>GOARCH</code> value
+  "<code>loong64</code>".
+  This means that Go files named <code>*_loong64.go</code> will now
+  be <a href="/pkg/go/build/#hdr-Build_Constraints">ignored by Go
+  tools</a> except when that GOARCH value is being used.
+</p>
+
 <h2 id="tools">Tools</h2>
 
 <h3 id="go-command">Go command</h3>
@@ -401,30 +412,37 @@ func Foo() bool {
 
 <p><!-- golang.org/issue/40724 -->
   Go 1.17 implements a new way of passing function arguments and results using
-  registers instead of the stack. This work is enabled for Linux, macOS, and
+  registers instead of the stack.
-  Windows on the 64-bit x86 architecture (the <code>linux/amd64</code>,
+  Benchmarks for a representative set of Go packages and programs show
-  <code>darwin/amd64</code>, <code>windows/amd64</code> ports). For a
+  performance improvements of about 5%, and a typical reduction in
-  representative set of Go packages and programs, benchmarking has shown
+  binary size of about 2%.
-  performance improvements of about 5%, and a typical reduction in binary size
+  This is currently enabled for Linux, macOS, and Windows on the
-  of about 2%.
+  64-bit x86 architecture (the <code>linux/amd64</code>,
+  <code>darwin/amd64</code>, and <code>windows/amd64</code> ports).
 </p>
 
 <p>
-  This change does not affect the functionality of any safe Go code. It can affect
+  This change does not affect the functionality of any safe Go code
-  code outside the <a href="/doc/go1compat">compatibility guidelines</a> with
+  and is designed to have no impact on most assembly code.
-  minimal impact. To maintain compatibility with existing assembly functions,
+  It may affect code that violates
-  adapter functions converting between the new register-based calling convention
+  the <a href="/pkg/unsafe#Pointer"><code>unsafe.Pointer</code></a>
-  and the previous stack-based calling convention (also known as ABI wrappers)
+  rules when accessing function arguments, or that depends on
-  are sometimes used. This is mostly invisible to users, except for assembly
+  undocumented behavior involving comparing function code pointers.
-  functions that have their addresses taken in Go. Using <code>reflect.ValueOf(fn).Pointer()</code>
+  To maintain compatibility with existing assembly functions, the
-  (or similar approaches such as via <code>unsafe.Pointer</code>) to get the address
+  compiler generates adapter functions that convert between the new
-  of an assembly function will now return the address of the ABI wrapper. This is
+  register-based calling convention and the previous stack-based
-  mostly harmless, except for special-purpose assembly code (such as accessing
+  calling convention.
-  thread-local storage or requiring a special stack alignment). Assembly functions
+  These adapters are typically invisible to users, except that taking
-  called indirectly from Go via <code>func</code> values will now be made through
+  the address of a Go function in assembly code or taking the address
-  ABI wrappers, which may cause a very small performance overhead. Also, calling
+  of an assembly function in Go code
-  Go functions from assembly may now go through ABI wrappers, with a very small
+  using <code>reflect.ValueOf(fn).Pointer()</code>
-  performance overhead.
+  or <code>unsafe.Pointer</code> will now return the address of the
+  adapter.
+  Code that depends on the value of these code pointers may no longer
+  behave as expected.
+  Adapters also may cause a very small performance overhead in two
+  cases: calling an assembly function indirectly from Go via
+  a <code>func</code> value, and calling Go functions from assembly.
 </p>
 
 <p><!-- CL 304470 -->
@@ -440,11 +458,14 @@ func Foo() bool {
 </p>
 
 <p><!-- CL 283112, golang.org/issue/28727 -->
-  Functions containing closures can now be inlined. One effect of this change is
+  Functions containing closures can now be inlined.
-  that a function with a closure may actually produce a distinct closure function
+  One effect of this change is that a function with a closure may
-  for each place that the function is inlined. Hence, this change could reveal
+  produce a distinct closure code pointer for each place that the
-  bugs where Go functions are compared (incorrectly) by pointer value. Go
+  function is inlined.
-  functions are by definition not comparable.
+  Go function values are not directly comparable, but this change
+  could reveal bugs in code that uses <code>reflect</code>
+  or <code>unsafe.Pointer</code> to bypass this language restriction
+  and compare functions by code pointer.
 </p>
 
 <h2 id="library">Core library</h2>
@@ -865,8 +886,8 @@ func Foo() bool {
   <dd>
     <p><!-- CL 272668 -->
       The new method <a href="/pkg/net/#IP.IsPrivate"><code>IP.IsPrivate</code></a> reports whether an address is
-      a private IPv4 address according to <a href="http://tools.ietf.org/html/rfc1918">RFC 1918</a>
+      a private IPv4 address according to <a href="https://datatracker.ietf.org/doc/rfc1918">RFC 1918</a>
-      or a local IPv6 address according <a href="http://tools.ietf.org/html/rfc4193">RFC 4193</a>.
+      or a local IPv6 address according <a href="https://datatracker.ietf.org/doc/rfc4193">RFC 4193</a>.
     </p>
 
     <p><!-- CL 301709 -->
@@ -968,6 +989,18 @@ func Foo() bool {
 
 <dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
   <dd>
+    <p><!-- CL 334669 -->
+      The new
+      <a href="/pkg/reflect/#Value.CanConvert"><code>Value.CanConvert</code></a>
+      method reports whether a value can be converted to a type.
+      This may be used to avoid a panic when converting a slice to an
+      array pointer type if the slice is too short.
+      Previously it was sufficient to use
+      <a href="/pkg/reflect/#Type.ConvertibleTo"><code>Type.ConvertibleTo</code></a>
+      for this, but the newly permitted conversion from slice to array
+      pointer type can panic even if the types are convertible.
+    </p>
+
     <p><!-- CL 266197 -->
       The new
       <a href="/pkg/reflect/#StructField.IsExported"><code>StructField.IsExported</code></a>
@@ -1132,10 +1165,13 @@ func Foo() bool {
 
     <p><!-- CL 293349 -->
       The new <a href="/pkg/time/#Time.UnixMilli"><code>Time.UnixMilli</code></a> and
-      <a href="/pkg/time/#Time.UnixMicro"><code>Time.UnixMicro</code></a> methods return the number of milliseconds and
+      <a href="/pkg/time/#Time.UnixMicro"><code>Time.UnixMicro</code></a>
-      microseconds elapsed since January 1, 1970 UTC respectively.<br>
+      methods return the number of milliseconds and microseconds elapsed since
-      The new <code>UnixMilli</code> and <code>UnixMicro</code> functions return local Time corresponding to given
+      January 1, 1970 UTC respectively.
-      Unix time.
+      <br />
+      The new <a href="/pkg/time/#UnixMilli"><code>UnixMilli</code></a> and
+      <a href="/pkg/time/#UnixMicro"><code>UnixMicro</code></a> functions
+      return the local <code>Time</code> corresponding to the given Unix time.
     </p>
 
     <p><!-- CL 300996 -->

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of Jul 1, 2021",
+	"Subtitle": "Version of Jul 26, 2021",
 	"Path": "/ref/spec"
 }-->
 
@@ -490,8 +490,8 @@ After a backslash, certain single-character escapes represent special values:
 \n   U+000A line feed or newline
 \r   U+000D carriage return
 \t   U+0009 horizontal tab
-\v   U+000b vertical tab
+\v   U+000B vertical tab
-\\   U+005c backslash
+\\   U+005C backslash
 \'   U+0027 single quote  (valid escape only within rune literals)
 \"   U+0022 double quote  (valid escape only within string literals)
 </pre>
@@ -4334,7 +4334,10 @@ s4 := (*[4]byte)(s)      // panics: len([4]byte) > len(s)
 
 var t []string
 t0 := (*[0]string)(t)    // t0 == nil
-t1 := (*[1]string)(t)    // panics: len([1]string) > len(s)
+t1 := (*[1]string)(t)    // panics: len([1]string) > len(t)
+
+u := make([]byte, 0)
+u0 = (*[0]byte)(u)       // u0 != nil
 </pre>
 
 <h3 id="Constant_expressions">Constant expressions</h3>

src/cmd/compile/internal/abi/abiutils.go

@@ -446,35 +446,20 @@ func (config *ABIConfig) ABIAnalyze(t *types.Type, setNname bool) *ABIParamResul
 	return result
 }
 
-// parameterUpdateMu protects the Offset field of function/method parameters (a subset of structure Fields)
-var parameterUpdateMu sync.Mutex
-
-// FieldOffsetOf returns a concurrency-safe version of f.Offset
-func FieldOffsetOf(f *types.Field) int64 {
-	parameterUpdateMu.Lock()
-	defer parameterUpdateMu.Unlock()
-	return f.Offset
-}
-
 func (config *ABIConfig) updateOffset(result *ABIParamResultInfo, f *types.Field, a ABIParamAssignment, isReturn, setNname bool) {
 	// Everything except return values in registers has either a frame home (if not in a register) or a frame spill location.
 	if !isReturn || len(a.Registers) == 0 {
 		// The type frame offset DOES NOT show effects of minimum frame size.
 		// Getting this wrong breaks stackmaps, see liveness/plive.go:WriteFuncMap and typebits/typebits.go:Set
-		parameterUpdateMu.Lock()
-		defer parameterUpdateMu.Unlock()
 		off := a.FrameOffset(result)
 		fOffset := f.Offset
 		if fOffset == types.BOGUS_FUNARG_OFFSET {
-			// Set the Offset the first time. After that, we may recompute it, but it should never change.
+			if setNname && f.Nname != nil {
-			f.Offset = off
-			if f.Nname != nil {
-				// always set it in this case.
 				f.Nname.(*ir.Name).SetFrameOffset(off)
 				f.Nname.(*ir.Name).SetIsOutputParamInRegisters(false)
 			}
-		} else if fOffset != off {
+		} else {
-			base.Fatalf("offset for %s at %s changed from %d to %d", f.Sym.Name, base.FmtPos(f.Pos), fOffset, off)
+			base.Fatalf("field offset for %s at %s has been set to %d", f.Sym.Name, base.FmtPos(f.Pos), fOffset)
 		}
 	} else {
 		if setNname && f.Nname != nil {

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

@@ -148,7 +148,7 @@ func dumpdata() {
 	if reflectdata.ZeroSize > 0 {
 		zero := base.PkgLinksym("go.map", "zero", obj.ABI0)
 		objw.Global(zero, int32(reflectdata.ZeroSize), obj.DUPOK|obj.RODATA)
-		zero.Set(obj.AttrContentAddressable, true)
+		zero.Set(obj.AttrStatic, true)
 	}
 
 	staticdata.WriteFuncSyms()

src/cmd/compile/internal/reflectdata/reflect.go

@@ -669,7 +669,7 @@ var kinds = []int{
 // tflag is documented in reflect/type.go.
 //
 // tflag values must be kept in sync with copies in:
-//	cmd/compile/internal/gc/reflect.go
+//	cmd/compile/internal/reflectdata/reflect.go
 //	cmd/link/internal/ld/decodesym.go
 //	reflect/type.go
 //	runtime/type.go

src/cmd/compile/internal/ssagen/ssa.go

@@ -1296,7 +1296,7 @@ func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrument
 		if f.Sym.IsBlank() {
 			continue
 		}
-		offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), abi.FieldOffsetOf(f), addr)
+		offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
 		s.instrumentFields(f.Type, offptr, kind)
 	}
 }
@@ -5053,19 +5053,23 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 		ft := fn.Type()
 		off := t.FieldOff(12) // TODO register args: be sure this isn't a hardcoded param stack offset.
 		args := n.Args
+		i0 := 0
 
 		// Set receiver (for interface calls). Always a pointer.
 		if rcvr != nil {
 			p := s.newValue1I(ssa.OpOffPtr, ft.Recv().Type.PtrTo(), off, addr)
 			s.store(types.Types[types.TUINTPTR], p, rcvr)
+			i0 = 1
 		}
 		// Set receiver (for method calls).
 		if n.Op() == ir.OCALLMETH {
 			base.Fatalf("OCALLMETH missed by walkCall")
 		}
 		// Set other args.
-		for _, f := range ft.Params().Fields().Slice() {
+		// This code is only used when RegabiDefer is not enabled, and arguments are always
-			s.storeArgWithBase(args[0], f.Type, addr, off+abi.FieldOffsetOf(f))
+		// passed on stack.
+		for i, f := range ft.Params().Fields().Slice() {
+			s.storeArgWithBase(args[0], f.Type, addr, off+params.InParam(i+i0).FrameOffset(params))
 			args = args[1:]
 		}
 
@@ -5078,7 +5082,6 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 		if stksize < int64(types.PtrSize) {
 			// We need room for both the call to deferprocStack and the call to
 			// the deferred function.
-			// TODO(register args) Revisit this if/when we pass args in registers.
 			stksize = int64(types.PtrSize)
 		}
 		call.AuxInt = stksize
@@ -6598,6 +6601,7 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
 
 	PtrSize := int64(types.PtrSize)
+	uintptrTyp := types.Types[types.TUINTPTR]
 
 	isAggregate := func(t *types.Type) bool {
 		return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice()
@@ -6641,12 +6645,8 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	n := 0
 	writebyte := func(o uint8) { wOff = objw.Uint8(x, wOff, o) }
 
-	// Write one non-aggrgate arg/field/element if there is room.
+	// Write one non-aggrgate arg/field/element.
-	// Returns whether to continue.
+	write1 := func(sz, offset int64) {
-	write1 := func(sz, offset int64) bool {
-		if n >= limit {
-			return false
-		}
 		if offset >= _special {
 			writebyte(_offsetTooLarge)
 		} else {
@@ -6654,7 +6654,6 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 			writebyte(uint8(sz))
 		}
 		n++
-		return true
 	}
 
 	// Visit t recursively and write it out.
@@ -6662,10 +6661,12 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	var visitType func(baseOffset int64, t *types.Type, depth int) bool
 	visitType = func(baseOffset int64, t *types.Type, depth int) bool {
 		if n >= limit {
+			writebyte(_dotdotdot)
 			return false
 		}
 		if !isAggregate(t) {
-			return write1(t.Size(), baseOffset)
+			write1(t.Size(), baseOffset)
+			return true
 		}
 		writebyte(_startAgg)
 		depth++
@@ -6675,58 +6676,47 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 			n++
 			return true
 		}
-		var r bool
 		switch {
 		case t.IsInterface(), t.IsString():
-			r = write1(PtrSize, baseOffset) &&
+			_ = visitType(baseOffset, uintptrTyp, depth) &&
-				write1(PtrSize, baseOffset+PtrSize)
+				visitType(baseOffset+PtrSize, uintptrTyp, depth)
 		case t.IsSlice():
-			r = write1(PtrSize, baseOffset) &&
+			_ = visitType(baseOffset, uintptrTyp, depth) &&
-				write1(PtrSize, baseOffset+PtrSize) &&
+				visitType(baseOffset+PtrSize, uintptrTyp, depth) &&
-				write1(PtrSize, baseOffset+PtrSize*2)
+				visitType(baseOffset+PtrSize*2, uintptrTyp, depth)
 		case t.IsComplex():
-			r = write1(t.Size()/2, baseOffset) &&
+			_ = visitType(baseOffset, types.FloatForComplex(t), depth) &&
-				write1(t.Size()/2, baseOffset+t.Size()/2)
+				visitType(baseOffset+t.Size()/2, types.FloatForComplex(t), depth)
 		case t.IsArray():
-			r = true
 			if t.NumElem() == 0 {
 				n++ // {} counts as a component
 				break
 			}
 			for i := int64(0); i < t.NumElem(); i++ {
 				if !visitType(baseOffset, t.Elem(), depth) {
-					r = false
 					break
 				}
 				baseOffset += t.Elem().Size()
 			}
 		case t.IsStruct():
-			r = true
 			if t.NumFields() == 0 {
 				n++ // {} counts as a component
 				break
 			}
 			for _, field := range t.Fields().Slice() {
 				if !visitType(baseOffset+field.Offset, field.Type, depth) {
-					r = false
 					break
 				}
 			}
 		}
-		if !r {
-			writebyte(_dotdotdot)
-		}
 		writebyte(_endAgg)
-		return r
+		return true
 	}
 
-	c := true
 	for _, a := range abiInfo.InParams() {
-		if !c {
+		if !visitType(a.FrameOffset(abiInfo), a.Type, 0) {
-			writebyte(_dotdotdot)
 			break
 		}
-		c = visitType(a.FrameOffset(abiInfo), a.Type, 0)
 	}
 	writebyte(_endSeq)
 	if wOff > maxLen {

src/cmd/compile/internal/typecheck/dcl.go

@@ -106,7 +106,17 @@ func Export(n *ir.Name) {
 // Redeclared emits a diagnostic about symbol s being redeclared at pos.
 func Redeclared(pos src.XPos, s *types.Sym, where string) {
 	if !s.Lastlineno.IsKnown() {
-		pkgName := DotImportRefs[s.Def.(*ir.Ident)]
+		var pkgName *ir.PkgName
+		if s.Def == nil {
+			for id, pkg := range DotImportRefs {
+				if id.Sym().Name == s.Name {
+					pkgName = pkg
+					break
+				}
+			}
+		} else {
+			pkgName = DotImportRefs[s.Def.(*ir.Ident)]
+		}
 		base.ErrorfAt(pos, "%v redeclared %s\n"+
 			"\t%v: previous declaration during import %q", s, where, base.FmtPos(pkgName.Pos()), pkgName.Pkg.Path)
 	} else {

src/cmd/compile/internal/typecheck/iimport.go

@@ -1540,7 +1540,7 @@ func (r *importReader) exprsOrNil() (a, b ir.Node) {
 func builtinCall(pos src.XPos, op ir.Op) *ir.CallExpr {
 	if go117ExportTypes {
 		// These should all be encoded as direct ops, not OCALL.
-		base.Fatalf("builtinCall should not be invoked when types are included in inport/export")
+		base.Fatalf("builtinCall should not be invoked when types are included in import/export")
 	}
 	return ir.NewCallExpr(pos, ir.OCALL, ir.NewIdent(base.Pos, types.BuiltinPkg.Lookup(ir.OpNames[op])), nil)
 }

src/cmd/compile/internal/types/fmt.go

@@ -109,14 +109,18 @@ func sconv(s *Sym, verb rune, mode fmtMode) string {
 		return "<S>"
 	}
 
-	if s.Name == "_" {
+	q := pkgqual(s.Pkg, verb, mode)
-		return "_"
+	if q == "" {
+		return s.Name
 	}
+
 	buf := fmtBufferPool.Get().(*bytes.Buffer)
 	buf.Reset()
 	defer fmtBufferPool.Put(buf)
 
-	symfmt(buf, s, verb, mode)
+	buf.WriteString(q)
+	buf.WriteByte('.')
+	buf.WriteString(s.Name)
 	return InternString(buf.Bytes())
 }
 
@@ -128,56 +132,49 @@ func sconv2(b *bytes.Buffer, s *Sym, verb rune, mode fmtMode) {
 		b.WriteString("<S>")
 		return
 	}
-	if s.Name == "_" {
-		b.WriteString("_")
-		return
-	}
 
 	symfmt(b, s, verb, mode)
 }
 
 func symfmt(b *bytes.Buffer, s *Sym, verb rune, mode fmtMode) {
+	if q := pkgqual(s.Pkg, verb, mode); q != "" {
+		b.WriteString(q)
+		b.WriteByte('.')
+	}
+	b.WriteString(s.Name)
+}
+
+// pkgqual returns the qualifier that should be used for printing
+// symbols from the given package in the given mode.
+// If it returns the empty string, no qualification is needed.
+func pkgqual(pkg *Pkg, verb rune, mode fmtMode) string {
 	if verb != 'S' {
 		switch mode {
 		case fmtGo: // This is for the user
-			if s.Pkg == BuiltinPkg || s.Pkg == LocalPkg {
+			if pkg == BuiltinPkg || pkg == LocalPkg {
-				b.WriteString(s.Name)
+				return ""
-				return
 			}
 
 			// If the name was used by multiple packages, display the full path,
-			if s.Pkg.Name != "" && NumImport[s.Pkg.Name] > 1 {
+			if pkg.Name != "" && NumImport[pkg.Name] > 1 {
-				fmt.Fprintf(b, "%q.%s", s.Pkg.Path, s.Name)
+				return strconv.Quote(pkg.Path)
-				return
 			}
-			b.WriteString(s.Pkg.Name)
+			return pkg.Name
-			b.WriteByte('.')
-			b.WriteString(s.Name)
-			return
 
 		case fmtDebug:
-			b.WriteString(s.Pkg.Name)
+			return pkg.Name
-			b.WriteByte('.')
-			b.WriteString(s.Name)
-			return
 
 		case fmtTypeIDName:
 			// dcommontype, typehash
-			b.WriteString(s.Pkg.Name)
+			return pkg.Name
-			b.WriteByte('.')
-			b.WriteString(s.Name)
-			return
 
 		case fmtTypeID:
 			// (methodsym), typesym, weaksym
-			b.WriteString(s.Pkg.Prefix)
+			return pkg.Prefix
-			b.WriteByte('.')
-			b.WriteString(s.Name)
-			return
 		}
 	}
 
-	b.WriteString(s.Name)
+	return ""
 }
 
 // Type

src/cmd/go/alldocs.go

@@ -1087,7 +1087,7 @@
 //
 // Usage:
 //
-// 	go mod edit [editing flags] [go.mod]
+// 	go mod edit [editing flags] [-fmt|-print|-json] [go.mod]
 //
 // Edit provides a command-line interface for editing go.mod,
 // for use primarily by tools or scripts. It reads only go.mod;
@@ -1202,7 +1202,7 @@
 // and one of its requirements. Each module is identified as a string of the form
 // path@version, except for the main module, which has no @version suffix.
 //
-// The -go flag causes graph to report the module graph as loaded by by the
+// The -go flag causes graph to report the module graph as loaded by the
 // given Go version, instead of the version indicated by the 'go' directive
 // in the go.mod file.
 //
@@ -1213,7 +1213,7 @@
 //
 // Usage:
 //
-// 	go mod init [module]
+// 	go mod init [module-path]
 //
 // Init initializes and writes a new go.mod file in the current directory, in
 // effect creating a new module rooted at the current directory. The go.mod file

src/cmd/go/go_test.go

@@ -2848,3 +2848,35 @@ func TestExecInDeletedDir(t *testing.T) {
 	// `go version` should not fail
 	tg.run("version")
 }
+
+// A missing C compiler should not force the net package to be stale.
+// Issue 47215.
+func TestMissingCC(t *testing.T) {
+	if !canCgo {
+		t.Skip("test is only meaningful on systems with cgo")
+	}
+	cc := os.Getenv("CC")
+	if cc == "" {
+		cc = "gcc"
+	}
+	if filepath.IsAbs(cc) {
+		t.Skipf(`"CC" (%s) is an absolute path`, cc)
+	}
+	_, err := exec.LookPath(cc)
+	if err != nil {
+		t.Skipf(`"CC" (%s) not on PATH`, cc)
+	}
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	netStale, _ := tg.isStale("net")
+	if netStale {
+		t.Skip(`skipping test because "net" package is currently stale`)
+	}
+
+	tg.setenv("PATH", "") // No C compiler on PATH.
+	netStale, _ = tg.isStale("net")
+	if netStale {
+		t.Error(`clearing "PATH" causes "net" to be stale`)
+	}
+}

src/cmd/go/internal/lockedfile/lockedfile_filelock.go

@@ -11,7 +11,6 @@ import (
 	"io/fs"
 	"os"
 
-	"cmd/go/internal/fsys"
 	"cmd/go/internal/lockedfile/internal/filelock"
 )
 
@@ -21,7 +20,7 @@ func openFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
 	// calls for Linux and Windows anyway, so it's simpler to use that approach
 	// consistently.
 
-	f, err := fsys.OpenFile(name, flag&^os.O_TRUNC, perm)
+	f, err := os.OpenFile(name, flag&^os.O_TRUNC, perm)
 	if err != nil {
 		return nil, err
 	}

src/cmd/go/internal/lockedfile/lockedfile_plan9.go

@@ -13,8 +13,6 @@ import (
 	"os"
 	"strings"
 	"time"
-
-	"cmd/go/internal/fsys"
 )
 
 // Opening an exclusive-use file returns an error.
@@ -59,7 +57,7 @@ func openFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
 	// If the file was unpacked or created by some other program, it might not
 	// have the ModeExclusive bit set. Set it before we call OpenFile, so that we
 	// can be confident that a successful OpenFile implies exclusive use.
-	if fi, err := fsys.Stat(name); err == nil {
+	if fi, err := os.Stat(name); err == nil {
 		if fi.Mode()&fs.ModeExclusive == 0 {
 			if err := os.Chmod(name, fi.Mode()|fs.ModeExclusive); err != nil {
 				return nil, err
@@ -72,7 +70,7 @@ func openFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
 	nextSleep := 1 * time.Millisecond
 	const maxSleep = 500 * time.Millisecond
 	for {
-		f, err := fsys.OpenFile(name, flag, perm|fs.ModeExclusive)
+		f, err := os.OpenFile(name, flag, perm|fs.ModeExclusive)
 		if err == nil {
 			return f, nil
 		}

src/cmd/go/internal/modcmd/edit.go

@@ -25,7 +25,7 @@ import (
 )
 
 var cmdEdit = &base.Command{
-	UsageLine: "go mod edit [editing flags] [go.mod]",
+	UsageLine: "go mod edit [editing flags] [-fmt|-print|-json] [go.mod]",
 	Short:     "edit go.mod from tools or scripts",
 	Long: `
 Edit provides a command-line interface for editing go.mod,

src/cmd/go/internal/modcmd/graph.go

@@ -26,7 +26,7 @@ in text form. Each line in the output has two space-separated fields: a module
 and one of its requirements. Each module is identified as a string of the form
 path@version, except for the main module, which has no @version suffix.
 
-The -go flag causes graph to report the module graph as loaded by by the
+The -go flag causes graph to report the module graph as loaded by the
 given Go version, instead of the version indicated by the 'go' directive
 in the go.mod file.
 

src/cmd/go/internal/modcmd/init.go

@@ -13,7 +13,7 @@ import (
 )
 
 var cmdInit = &base.Command{
-	UsageLine: "go mod init [module]",
+	UsageLine: "go mod init [module-path]",
 	Short:     "initialize new module in current directory",
 	Long: `
 Init initializes and writes a new go.mod file in the current directory, in

src/cmd/go/internal/modfetch/codehost/git_test.go

@@ -8,7 +8,6 @@ import (
 	"archive/zip"
 	"bytes"
 	"flag"
-	"fmt"
 	"internal/testenv"
 	"io"
 	"io/fs"
@@ -47,12 +46,6 @@ var altRepos = []string{
 var localGitRepo string
 
 func testMain(m *testing.M) int {
-	if _, err := exec.LookPath("git"); err != nil {
-		fmt.Fprintln(os.Stderr, "skipping because git binary not found")
-		fmt.Println("PASS")
-		return 0
-	}
-
 	dir, err := os.MkdirTemp("", "gitrepo-test-")
 	if err != nil {
 		log.Fatal(err)
@@ -60,6 +53,7 @@ func testMain(m *testing.M) int {
 	defer os.RemoveAll(dir)
 
 	if testenv.HasExternalNetwork() && testenv.HasExec() {
+		if _, err := exec.LookPath("git"); err == nil {
 			// Clone gitrepo1 into a local directory.
 			// If we use a file:// URL to access the local directory,
 			// then git starts up all the usual protocol machinery,
@@ -72,11 +66,12 @@ func testMain(m *testing.M) int {
 				log.Fatal(err)
 			}
 		}
+	}
 
 	return m.Run()
 }
 
-func testRepo(remote string) (Repo, error) {
+func testRepo(t *testing.T, remote string) (Repo, error) {
 	if remote == "localGitRepo" {
 		// Convert absolute path to file URL. LocalGitRepo will not accept
 		// Windows absolute paths because they look like a host:path remote.
@@ -87,15 +82,17 @@ func testRepo(remote string) (Repo, error) {
 		} else {
 			url = "file:///" + filepath.ToSlash(localGitRepo)
 		}
+		testenv.MustHaveExecPath(t, "git")
 		return LocalGitRepo(url)
 	}
-	kind := "git"
+	vcs := "git"
 	for _, k := range []string{"hg"} {
 		if strings.Contains(remote, "/"+k+"/") {
-			kind = k
+			vcs = k
 		}
 	}
-	return NewRepo(kind, remote)
+	testenv.MustHaveExecPath(t, vcs)
+	return NewRepo(vcs, remote)
 }
 
 var tagsTests = []struct {
@@ -116,7 +113,7 @@ func TestTags(t *testing.T) {
 
 	for _, tt := range tagsTests {
 		f := func(t *testing.T) {
-			r, err := testRepo(tt.repo)
+			r, err := testRepo(t, tt.repo)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -168,7 +165,7 @@ func TestLatest(t *testing.T) {
 
 	for _, tt := range latestTests {
 		f := func(t *testing.T) {
-			r, err := testRepo(tt.repo)
+			r, err := testRepo(t, tt.repo)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -221,7 +218,7 @@ func TestReadFile(t *testing.T) {
 
 	for _, tt := range readFileTests {
 		f := func(t *testing.T) {
-			r, err := testRepo(tt.repo)
+			r, err := testRepo(t, tt.repo)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -412,7 +409,7 @@ func TestReadZip(t *testing.T) {
 
 	for _, tt := range readZipTests {
 		f := func(t *testing.T) {
-			r, err := testRepo(tt.repo)
+			r, err := testRepo(t, tt.repo)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -581,7 +578,7 @@ func TestStat(t *testing.T) {
 
 	for _, tt := range statTests {
 		f := func(t *testing.T) {
-			r, err := testRepo(tt.repo)
+			r, err := testRepo(t, tt.repo)
 			if err != nil {
 				t.Fatal(err)
 			}

src/cmd/go/internal/modfetch/coderepo.go

@@ -864,22 +864,25 @@ func (r *codeRepo) GoMod(version string) (data []byte, err error) {
 	data, err = r.code.ReadFile(rev, path.Join(dir, "go.mod"), codehost.MaxGoMod)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return r.legacyGoMod(rev, dir), nil
+			return LegacyGoMod(r.modPath), nil
 		}
 		return nil, err
 	}
 	return data, nil
 }
 
-func (r *codeRepo) legacyGoMod(rev, dir string) []byte {
+// LegacyGoMod generates a fake go.mod file for a module that doesn't have one.
+// The go.mod file contains a module directive and nothing else: no go version,
+// no requirements.
+//
 // We used to try to build a go.mod reflecting pre-existing
 // package management metadata files, but the conversion
 // was inherently imperfect (because those files don't have
 // exactly the same semantics as go.mod) and, when done
 // for dependencies in the middle of a build, impossible to
 // correct. So we stopped.
-	// Return a fake go.mod that simply declares the module path.
+func LegacyGoMod(modPath string) []byte {
-	return []byte(fmt.Sprintf("module %s\n", modfile.AutoQuote(r.modPath)))
+	return []byte(fmt.Sprintf("module %s\n", modfile.AutoQuote(modPath)))
 }
 
 func (r *codeRepo) modPrefix(rev string) string {

src/cmd/go/internal/modfetch/fetch.go

@@ -22,6 +22,7 @@ import (
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
+	"cmd/go/internal/fsys"
 	"cmd/go/internal/lockedfile"
 	"cmd/go/internal/par"
 	"cmd/go/internal/robustio"
@@ -416,7 +417,18 @@ func initGoSum() (bool, error) {
 
 	goSum.m = make(map[module.Version][]string)
 	goSum.status = make(map[modSum]modSumStatus)
-	data, err := lockedfile.Read(GoSumFile)
+	var (
+		data []byte
+		err  error
+	)
+	if actualSumFile, ok := fsys.OverlayPath(GoSumFile); ok {
+		// Don't lock go.sum if it's part of the overlay.
+		// On Plan 9, locking requires chmod, and we don't want to modify any file
+		// in the overlay. See #44700.
+		data, err = os.ReadFile(actualSumFile)
+	} else {
+		data, err = lockedfile.Read(GoSumFile)
+	}
 	if err != nil && !os.IsNotExist(err) {
 		return false, err
 	}
@@ -718,6 +730,9 @@ Outer:
 	if readonly {
 		return ErrGoSumDirty
 	}
+	if _, ok := fsys.OverlayPath(GoSumFile); ok {
+		base.Fatalf("go: updates to go.sum needed, but go.sum is part of the overlay specified with -overlay")
+	}
 
 	// Make a best-effort attempt to acquire the side lock, only to exclude
 	// previous versions of the 'go' command from making simultaneous edits.

src/cmd/go/internal/modload/init.go

@@ -191,7 +191,7 @@ type Root int
 const (
 	// AutoRoot is the default for most commands. modload.Init will look for
 	// a go.mod file in the current directory or any parent. If none is found,
-	// modules may be disabled (GO111MODULE=on) or commands may run in a
+	// modules may be disabled (GO111MODULE=auto) or commands may run in a
 	// limited module mode.
 	AutoRoot Root = iota
 
@@ -1364,6 +1364,13 @@ func commitRequirements(ctx context.Context, goVersion string, rs *Requirements)
 		}
 		return
 	}
+	gomod := ModFilePath()
+	if _, ok := fsys.OverlayPath(gomod); ok {
+		if dirty {
+			base.Fatalf("go: updates to go.mod needed, but go.mod is part of the overlay specified with -overlay")
+		}
+		return
+	}
 
 	new, err := modFile.Format()
 	if err != nil {

src/cmd/go/internal/modload/load.go

@@ -715,20 +715,6 @@ func (mms *MainModuleSet) DirImportPath(ctx context.Context, dir string) (path s
 	return ".", module.Version{}
 }
 
-// TargetPackages returns the list of packages in the target (top-level) module
-// matching pattern, which may be relative to the working directory, under all
-// build tag settings.
-func TargetPackages(ctx context.Context, pattern string) *search.Match {
-	// TargetPackages is relative to the main module, so ensure that the main
-	// module is a thing that can contain packages.
-	LoadModFile(ctx) // Sets Target.
-	ModRoot()        // Emits an error if Target cannot contain packages.
-
-	m := search.NewMatch(pattern)
-	matchPackages(ctx, m, imports.AnyTags(), omitStd, MainModules.Versions())
-	return m
-}
-
 // ImportMap returns the actual package import path
 // for an import path found in source code.
 // If the given import path does not appear in the source code
@@ -760,29 +746,6 @@ func PackageModule(path string) module.Version {
 	return pkg.mod
 }
 
-// PackageImports returns the imports for the package named by the import path.
-// Test imports will be returned as well if tests were loaded for the package
-// (i.e., if "all" was loaded or if LoadTests was set and the path was matched
-// by a command line argument). PackageImports will return nil for
-// unknown package paths.
-func PackageImports(path string) (imports, testImports []string) {
-	pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
-	if !ok {
-		return nil, nil
-	}
-	imports = make([]string, len(pkg.imports))
-	for i, p := range pkg.imports {
-		imports[i] = p.path
-	}
-	if pkg.test != nil {
-		testImports = make([]string, len(pkg.test.imports))
-		for i, p := range pkg.test.imports {
-			testImports[i] = p.path
-		}
-	}
-	return imports, testImports
-}
-
 // Lookup returns the source directory, import path, and any loading error for
 // the package at path as imported from the package in parentDir.
 // Lookup requires that one of the Load functions in this package has already
@@ -1883,7 +1846,7 @@ func (ld *loader) checkTidyCompatibility(ctx context.Context, rs *Requirements)
 		fmt.Fprintf(os.Stderr, "If reproducibility with go %s is not needed:\n\tgo mod tidy%s -compat=%s\n", ld.TidyCompatibleVersion, goFlag, ld.GoVersion)
 
 		// TODO(#46141): Populate the linked wiki page.
-		fmt.Fprintf(os.Stderr, "For other options, see:\n\thttps://golang.org/wiki/PruningModules\n")
+		fmt.Fprintf(os.Stderr, "For other options, see:\n\thttps://golang.org/doc/modules/pruning\n")
 	}
 
 	mg, err := rs.Graph(ctx)

src/cmd/go/internal/modload/modfile.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"os"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -15,6 +16,7 @@ import (
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
+	"cmd/go/internal/fsys"
 	"cmd/go/internal/lockedfile"
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/par"
@@ -614,39 +616,14 @@ func rawGoModSummary(m module.Version) (*modFileSummary, error) {
 	}
 	c := rawGoModSummaryCache.Do(m, func() interface{} {
 		summary := new(modFileSummary)
-		var f *modfile.File
+		name, data, err := rawGoModData(m)
-		if m.Version == "" {
-			// m is a replacement module with only a file path.
-			dir := m.Path
-			if !filepath.IsAbs(dir) {
-				dir = filepath.Join(ModRoot(), dir)
-			}
-			gomod := filepath.Join(dir, "go.mod")
-
-			data, err := lockedfile.Read(gomod)
-			if err != nil {
-				return cached{nil, module.VersionError(m, fmt.Errorf("reading %s: %v", base.ShortPath(gomod), err))}
-			}
-			f, err = modfile.ParseLax(gomod, data, nil)
-			if err != nil {
-				return cached{nil, module.VersionError(m, fmt.Errorf("parsing %s: %v", base.ShortPath(gomod), err))}
-			}
-		} else {
-			if !semver.IsValid(m.Version) {
-				// Disallow the broader queries supported by fetch.Lookup.
-				base.Fatalf("go: internal error: %s@%s: unexpected invalid semantic version", m.Path, m.Version)
-			}
-
-			data, err := modfetch.GoMod(m.Path, m.Version)
 		if err != nil {
 			return cached{nil, err}
 		}
-			f, err = modfile.ParseLax("go.mod", data, nil)
+		f, err := modfile.ParseLax(name, data, nil)
 		if err != nil {
-				return cached{nil, module.VersionError(m, fmt.Errorf("parsing go.mod: %v", err))}
+			return cached{nil, module.VersionError(m, fmt.Errorf("parsing %s: %v", base.ShortPath(name), err))}
 		}
-		}
-
 		if f.Module != nil {
 			summary.module = f.Module.Mod
 			summary.deprecated = f.Module.Deprecated
@@ -682,6 +659,43 @@ func rawGoModSummary(m module.Version) (*modFileSummary, error) {
 
 var rawGoModSummaryCache par.Cache // module.Version → rawGoModSummary result
 
+// rawGoModData returns the content of the go.mod file for module m, ignoring
+// all replacements that may apply to m.
+//
+// rawGoModData cannot be used on the Target module.
+//
+// Unlike rawGoModSummary, rawGoModData does not cache its results in memory.
+// Use rawGoModSummary instead unless you specifically need these bytes.
+func rawGoModData(m module.Version) (name string, data []byte, err error) {
+	if m.Version == "" {
+		// m is a replacement module with only a file path.
+		dir := m.Path
+		if !filepath.IsAbs(dir) {
+			dir = filepath.Join(ModRoot(), dir)
+		}
+		name = filepath.Join(dir, "go.mod")
+		if gomodActual, ok := fsys.OverlayPath(name); ok {
+			// Don't lock go.mod if it's part of the overlay.
+			// On Plan 9, locking requires chmod, and we don't want to modify any file
+			// in the overlay. See #44700.
+			data, err = os.ReadFile(gomodActual)
+		} else {
+			data, err = lockedfile.Read(gomodActual)
+		}
+		if err != nil {
+			return "", nil, module.VersionError(m, fmt.Errorf("reading %s: %v", base.ShortPath(name), err))
+		}
+	} else {
+		if !semver.IsValid(m.Version) {
+			// Disallow the broader queries supported by fetch.Lookup.
+			base.Fatalf("go: internal error: %s@%s: unexpected invalid semantic version", m.Path, m.Version)
+		}
+		name = "go.mod"
+		data, err = modfetch.GoMod(m.Path, m.Version)
+	}
+	return name, data, err
+}
+
 // queryLatestVersionIgnoringRetractions looks up the latest version of the
 // module with the given path without considering retracted or excluded
 // versions.

src/cmd/go/internal/modload/query.go

@@ -5,13 +5,13 @@
 package modload
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"io/fs"
 	"os"
 	pathpkg "path"
-	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
@@ -933,8 +933,8 @@ func (e *PackageNotInModuleError) ImportPath() string {
 	return ""
 }
 
-// ModuleHasRootPackage returns whether module m contains a package m.Path.
+// moduleHasRootPackage returns whether module m contains a package m.Path.
-func ModuleHasRootPackage(ctx context.Context, m module.Version) (bool, error) {
+func moduleHasRootPackage(ctx context.Context, m module.Version) (bool, error) {
 	needSum := false
 	root, isLocal, err := fetch(ctx, m, needSum)
 	if err != nil {
@@ -944,14 +944,32 @@ func ModuleHasRootPackage(ctx context.Context, m module.Version) (bool, error) {
 	return ok, err
 }
 
-func versionHasGoMod(ctx context.Context, m module.Version) (bool, error) {
+// versionHasGoMod returns whether a version has a go.mod file.
-	needSum := false
+//
-	root, _, err := fetch(ctx, m, needSum)
+// versionHasGoMod fetches the go.mod file (possibly a fake) and true if it
+// contains anything other than a module directive with the same path. When a
+// module does not have a real go.mod file, the go command acts as if it had one
+// that only contained a module directive. Normal go.mod files created after
+// 1.12 at least have a go directive.
+//
+// This function is a heuristic, since it's possible to commit a file that would
+// pass this test. However, we only need a heurstic for determining whether
+// +incompatible versions may be "latest", which is what this function is used
+// for.
+//
+// This heuristic is useful for two reasons: first, when using a proxy,
+// this lets us fetch from the .mod endpoint which is much faster than the .zip
+// endpoint. The .mod file is used anyway, even if the .zip file contains a
+// go.mod with different content. Second, if we don't fetch the .zip, then
+// we don't need to verify it in go.sum. This makes 'go list -m -u' faster
+// and simpler.
+func versionHasGoMod(_ context.Context, m module.Version) (bool, error) {
+	_, data, err := rawGoModData(m)
 	if err != nil {
 		return false, err
 	}
-	fi, err := os.Stat(filepath.Join(root, "go.mod"))
+	isFake := bytes.Equal(data, modfetch.LegacyGoMod(m.Path))
-	return err == nil && !fi.IsDir(), nil
+	return !isFake, nil
 }
 
 // A versionRepo is a subset of modfetch.Repo that can report information about

src/cmd/go/internal/work/exec.go

@@ -252,9 +252,16 @@ func (b *Builder) buildActionID(a *Action) cache.ActionID {
 
 		ccExe := b.ccExe()
 		fmt.Fprintf(h, "CC=%q %q %q %q\n", ccExe, cppflags, cflags, ldflags)
+		// Include the C compiler tool ID so that if the C
+		// compiler changes we rebuild the package.
+		// But don't do that for standard library packages like net,
+		// so that the prebuilt .a files from a Go binary install
+		// don't need to be rebuilt with the local compiler.
+		if !p.Standard {
 			if ccID, err := b.gccToolID(ccExe[0], "c"); err == nil {
 				fmt.Fprintf(h, "CC ID=%q\n", ccID)
 			}
+		}
 		if len(p.CXXFiles)+len(p.SwigCXXFiles) > 0 {
 			cxxExe := b.cxxExe()
 			fmt.Fprintf(h, "CXX=%q %q\n", cxxExe, cxxflags)

src/cmd/go/testdata/script/mod_overlay.txt

@@ -21,7 +21,7 @@ go list -deps -overlay overlay.json .
 cd $WORK/gopath/src/get-doesnt-add-dep
 cp $WORK/overlay/get_doesnt_add_dep_go_mod $WORK/want_go_mod
 ! go get -d -overlay overlay.json .
-stderr 'overlaid files can''t be opened for write'
+stderr '^go: updates to go.mod needed, but go.mod is part of the overlay specified with -overlay$'
 cmp $WORK/overlay/get_doesnt_add_dep_go_mod $WORK/want_go_mod
 
 # Content of overlaid go.sum is used.
@@ -41,10 +41,10 @@ go mod verify -overlay overlay.json
 # attempting to update the file
 cp incomplete-sum-file $WORK/overlay/overlay-sum-used-correct-sums
 ! go get -d -overlay overlay.json .
-stderr 'overlaid files can''t be opened for write'
+stderr '^go: updates to go.sum needed, but go.sum is part of the overlay specified with -overlay$'
 cmp incomplete-sum-file $WORK/overlay/overlay-sum-used-correct-sums
 ! go mod tidy -overlay overlay.json
-stderr 'overlaid files can''t be opened for write'
+stderr '^go: updates to go.sum needed, but go.sum is part of the overlay specified with -overlay$'
 cmp incomplete-sum-file $WORK/overlay/overlay-sum-used-correct-sums
 
 # -overlay works with -modfile.
@@ -56,7 +56,7 @@ go list -modfile=alternate.mod -overlay overlay.json .
 stdout 'found.the/module'
 # Even with -modfile, overlaid files can't be opened for write.
 ! go get -modfile=alternate.mod -overlay overlay.json -d rsc.io/quote
-stderr 'overlaid files can''t be opened for write'
+stderr '^go: updates to go.mod needed, but go.mod is part of the overlay specified with -overlay$'
 
 # Carving out a module by adding an overlaid go.mod file
 cd $WORK/gopath/src/carve
@@ -78,7 +78,7 @@ go list -overlay overlay.json all
 stdout ^carve2/nomod$
 # Editing go.mod file fails because overlay is read only
 ! go get -overlay overlay.json -d rsc.io/quote
-stderr 'overlaid files can''t be opened for write'
+stderr '^go: updates to go.mod needed, but go.mod is part of the overlay specified with -overlay$'
 ! grep rsc.io/quote $WORK/overlay/carve2-nomod-go.mod
 # Editing go.mod file succeeds because we use -modfile to redirect to same file
 go get -overlay overlay.json -modfile $WORK/overlay/carve2-nomod-go.mod -d rsc.io/quote

src/cmd/go/testdata/script/mod_tidy_compat_ambiguous.txt

@@ -23,7 +23,7 @@ cp go.mod go.mod.orig
 
 stderr '^example\.com/m imports\n\texample\.net/indirect imports\n\texample\.net/ambiguous/nested/pkg loaded from example\.net/ambiguous/nested@v0\.1\.0,\n\tbut go 1.16 would fail to locate it:\n\tambiguous import: found package example\.net/ambiguous/nested/pkg in multiple modules:\n\texample\.net/ambiguous v0.1.0 \(.*\)\n\texample\.net/ambiguous/nested v0.1.0 \(.*\)\n\n'
 
-stderr '\n\nTo proceed despite packages unresolved in go 1\.16:\n\tgo mod tidy -e\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/wiki/PruningModules\n'
+stderr '\n\nTo proceed despite packages unresolved in go 1\.16:\n\tgo mod tidy -e\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
 cmp go.mod go.mod.orig
 

src/cmd/go/testdata/script/mod_tidy_compat_deleted.txt

@@ -19,7 +19,7 @@ cp go.mod go.mod.orig
 
 stderr '^example\.com/m imports\n\texample\.net/deleted loaded from example\.net/deleted@v0\.1\.0,\n\tbut go 1\.16 would fail to locate it in example\.net/deleted@v0\.2\.0\n\n'
 
-stderr '\n\nTo upgrade to the versions selected by go 1.16, leaving some packages unresolved:\n\tgo mod tidy -e -go=1\.16 && go mod tidy -e -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/wiki/PruningModules\n'
+stderr '\n\nTo upgrade to the versions selected by go 1.16, leaving some packages unresolved:\n\tgo mod tidy -e -go=1\.16 && go mod tidy -e -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1\.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
 
 # The suggested 'go mod tidy -e' command should proceed anyway.

src/cmd/go/testdata/script/mod_tidy_compat_implicit.txt

@@ -33,7 +33,7 @@ env MODFMT='{{with .Module}}{{.Path}} {{.Version}}{{end}}'
 cp go.mod go.mod.orig
 ! go mod tidy
 stderr '^example\.com/m imports\n\texample\.net/lazy tested by\n\texample\.net/lazy.test imports\n\texample\.com/retract/incompatible loaded from example\.com/retract/incompatible@v1\.0\.0,\n\tbut go 1\.16 would select v2\.0\.0\+incompatible\n\n'
-stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=1\.16 && go mod tidy -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1.17\nFor other options, see:\n\thttps://golang\.org/wiki/PruningModules\n'
+stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=1\.16 && go mod tidy -go=1\.17\nIf reproducibility with go 1.16 is not needed:\n\tgo mod tidy -compat=1.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
 cmp go.mod go.mod.orig
 

src/cmd/go/testdata/script/mod_tidy_compat_incompatible.txt

@@ -33,7 +33,7 @@ env MODFMT='{{with .Module}}{{.Path}} {{.Version}}{{end}}'
 cp go.mod go.mod.orig
 ! go mod tidy
 stderr '^example\.com/m imports\n\texample\.net/lazy imports\n\texample\.com/retract/incompatible loaded from example\.com/retract/incompatible@v1\.0\.0,\n\tbut go 1\.16 would select v2\.0\.0\+incompatible\n\n'
-stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=1\.16 && go mod tidy -go=1\.17\nIf reproducibility with go 1\.16 is not needed:\n\tgo mod tidy -compat=1.17\nFor other options, see:\n\thttps://golang\.org/wiki/PruningModules\n'
+stderr '\n\nTo upgrade to the versions selected by go 1\.16:\n\tgo mod tidy -go=1\.16 && go mod tidy -go=1\.17\nIf reproducibility with go 1\.16 is not needed:\n\tgo mod tidy -compat=1.17\nFor other options, see:\n\thttps://golang\.org/doc/modules/pruning\n'
 
 cmp go.mod go.mod.orig
 

src/cmd/go/testdata/script/mod_update_sum_readonly.txt

@@ -0,0 +1,34 @@
+# When finding the latest version of a module, we should not download version
+# contents. Previously, we downloaded .zip files to determine whether a real
+# .mod file was present in order to decide whether +incompatible versions
+# could be "latest".
+#
+# Verifies #47377.
+
+# rsc.io/breaker has two versions, neither of which has a .mod file.
+go list -m -versions rsc.io/breaker
+stdout '^rsc.io/breaker v1.0.0 v2.0.0\+incompatible$'
+go mod download rsc.io/breaker@v1.0.0
+! grep '^go' $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v1.0.0.mod
+go mod download rsc.io/breaker@v2.0.0+incompatible
+! grep '^go' $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v2.0.0+incompatible.mod
+
+# Delete downloaded .zip files.
+go clean -modcache
+
+# Check for updates.
+go list -m -u rsc.io/breaker
+stdout '^rsc.io/breaker v1.0.0 \[v2.0.0\+incompatible\]$'
+
+# We should not have downloaded zips.
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v1.0.0.zip
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v2.0.0+incompatible.zip
+
+-- go.mod --
+module m
+
+go 1.16
+
+require rsc.io/breaker v1.0.0
+-- go.sum --
+rsc.io/breaker v1.0.0/go.mod h1:s5yxDXvD88U1/ESC23I2FK3Lkv4YIKaB1ij/Hbm805g=

src/cmd/link/internal/ld/decodesym.go

@@ -16,12 +16,12 @@ import (
 
 // Decoding the type.* symbols.	 This has to be in sync with
 // ../../runtime/type.go, or more specifically, with what
-// cmd/compile/internal/gc/reflect.go stuffs in these.
+// cmd/compile/internal/reflectdata/reflect.go stuffs in these.
 
 // tflag is documented in reflect/type.go.
 //
 // tflag values must be kept in sync with copies in:
-//	cmd/compile/internal/gc/reflect.go
+//	cmd/compile/internal/reflectdata/reflect.go
 //	cmd/link/internal/ld/decodesym.go
 //	reflect/type.go
 //	runtime/type.go

src/cmd/link/internal/loader/loader.go

@@ -459,6 +459,15 @@ func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind in
 		if l.flags&FlagStrictDups != 0 {
 			l.checkdup(name, r, li, oldi)
 		}
+		// Fix for issue #47185 -- given two dupok symbols with
+		// different sizes, favor symbol with larger size. See
+		// also issue #46653.
+		szdup := l.SymSize(oldi)
+		sz := int64(r.Sym(li).Siz())
+		if szdup < sz {
+			// new symbol overwrites old symbol.
+			l.objSyms[oldi] = objSym{r.objidx, li}
+		}
 		return oldi
 	}
 	oldr, oldli := l.toLocal(oldi)

src/cmd/vet/main.go

@@ -1,3 +1,7 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package main
 
 import (

src/cmd/vet/testdata/copylock/copylock.go

@@ -1,3 +1,7 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package copylock
 
 import "sync"

src/cmd/vet/testdata/httpresponse/httpresponse.go

@@ -1,3 +1,7 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package httpresponse
 
 import (

src/cmd/vet/testdata/testingpkg/tests.go

@@ -1 +1,5 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package testdata

src/cmd/vet/testdata/testingpkg/tests_test.go

@@ -1,3 +1,7 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package testdata
 
 func Example_BadSuffix() {} // ERROR "Example_BadSuffix has malformed example suffix: BadSuffix"

src/crypto/tls/key_agreement.go

@@ -86,7 +86,11 @@ func (ka rsaKeyAgreement) generateClientKeyExchange(config *Config, clientHello
 		return nil, nil, err
 	}
 
-	encrypted, err := rsa.EncryptPKCS1v15(config.rand(), cert.PublicKey.(*rsa.PublicKey), preMasterSecret)
+	rsaKey, ok := cert.PublicKey.(*rsa.PublicKey)
+	if !ok {
+		return nil, nil, errors.New("tls: server certificate contains incorrect key type for selected ciphersuite")
+	}
+	encrypted, err := rsa.EncryptPKCS1v15(config.rand(), rsaKey, preMasterSecret)
 	if err != nil {
 		return nil, nil, err
 	}

src/crypto/x509/root.go

@@ -8,7 +8,7 @@ package x509
 // argument to the latest security_certificates version from
 // https://opensource.apple.com/source/security_certificates/
 // and run "go generate". See https://golang.org/issue/38843.
-//go:generate go run root_ios_gen.go -version 55188.40.9
+//go:generate go run root_ios_gen.go -version 55188.120.1.0.1
 
 import "sync"
 

src/crypto/x509/root_ios.go

@@ -1,4 +1,4 @@
-// Code generated by root_ios_gen.go -version 55188.40.9; DO NOT EDIT.
+// Code generated by root_ios_gen.go -version 55188.120.1.0.1; DO NOT EDIT.
 // Update the version in root.go and regenerate with "go generate".
 
 //go:build ios && !x509omitbundledroots
@@ -2223,6 +2223,41 @@ uOJAf/sKbvu+M8k8o4TVMAoGCCqGSM49BAMCA0gAMEUCIQDckqGgE6bPA7DmxCGX
 kPoUVy0D7O48027KqGx2vKLeuwIgJ6iFJzWbVsaj8kfSt24bAgAXqmemFZHe+pTs
 ewv4n4Q=
 -----END CERTIFICATE-----
+# "GlobalSign"
+# 2C AB EA FE 37 D0 6C A2 2A BA 73 91 C0 03 3D 25
+# 98 29 52 C4 53 64 73 49 76 3A 3A B5 AD 6C CF 69
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
 # "GlobalSign Root CA"
 # EB D4 10 40 E4 BB 3E C7 42 C9 E3 81 D3 1E F2 A4
 # 1A 48 B6 68 5C 96 E7 CE F3 C1 DF 6C D4 33 1C 99

src/go/build/syslist.go

@@ -8,4 +8,4 @@ package build
 // Do not remove from this list, as these are used for go/build filename matching.
 
 const goosList = "aix android darwin dragonfly freebsd hurd illumos ios js linux nacl netbsd openbsd plan9 solaris windows zos "
-const goarchList = "386 amd64 amd64p32 arm armbe arm64 arm64be ppc64 ppc64le mips mipsle mips64 mips64le mips64p32 mips64p32le ppc riscv riscv64 s390 s390x sparc sparc64 wasm "
+const goarchList = "386 amd64 amd64p32 arm armbe arm64 arm64be ppc64 ppc64le loong64 mips mipsle mips64 mips64le mips64p32 mips64p32le ppc riscv riscv64 s390 s390x sparc sparc64 wasm "

src/go/types/api_test.go

@@ -322,6 +322,18 @@ func TestTypesInfo(t *testing.T) {
 			`[][]struct{}`,
 		},
 
+		// issue 47243
+		{`package issue47243_a; var x int32; var _ = x << 3`, `3`, `untyped int`},
+		{`package issue47243_b; var x int32; var _ = x << 3.`, `3.`, `uint`}, // issue 47410: should be untyped float
+		{`package issue47243_c; var x int32; var _ = 1 << x`, `1 << x`, `int`},
+		{`package issue47243_d; var x int32; var _ = 1 << x`, `1`, `int`},
+		{`package issue47243_e; var x int32; var _ = 1 << 2`, `1`, `untyped int`},
+		{`package issue47243_f; var x int32; var _ = 1 << 2`, `2`, `untyped int`},
+		{`package issue47243_g; var x int32; var _ = int(1) << 2`, `2`, `untyped int`},
+		{`package issue47243_h; var x int32; var _ = 1 << (2 << x)`, `1`, `int`},
+		{`package issue47243_i; var x int32; var _ = 1 << (2 << x)`, `(2 << x)`, `untyped int`},
+		{`package issue47243_j; var x int32; var _ = 1 << (2 << x)`, `2`, `untyped int`},
+
 		// tests for broken code that doesn't parse or type-check
 		{broken + `x0; func _() { var x struct {f string}; x.f := 0 }`, `x.f`, `string`},
 		{broken + `x1; func _() { var z string; type x struct {f string}; y := &x{q: z}}`, `z`, `string`},

src/go/types/check_test.go

@@ -344,6 +344,13 @@ func TestIssue46453(t *testing.T) {
 	checkFiles(t, nil, "", []string{"issue46453.go"}, [][]byte{[]byte(src)}, false, nil)
 }
 
+func TestIssue47243_TypedRHS(t *testing.T) {
+	// The RHS of the shift expression below overflows uint on 32bit platforms,
+	// but this is OK as it is explicitly typed.
+	const src = "package issue47243\n\nvar a uint64; var _ = a << uint64(4294967296)" // uint64(1<<32)
+	checkFiles(t, &StdSizes{4, 4}, "", []string{"p.go"}, [][]byte{[]byte(src)}, false, nil)
+}
+
 func TestCheck(t *testing.T)     { DefPredeclaredTestFuncs(); testDir(t, "check") }
 func TestExamples(t *testing.T)  { testDir(t, "examples") }
 func TestFixedbugs(t *testing.T) { testDir(t, "fixedbugs") }

src/go/types/expr.go

@@ -778,32 +778,48 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
 	// spec: "The right operand in a shift expression must have integer type
 	// or be an untyped constant representable by a value of type uint."
 
-	// Provide a good error message for negative shift counts.
+	// Check that constants are representable by uint, but do not convert them
+	// (see also issue #47243).
 	if y.mode == constant_ {
+		// Provide a good error message for negative shift counts.
 		yval := constant.ToInt(y.val) // consider -1, 1.0, but not -1.1
 		if yval.Kind() == constant.Int && constant.Sign(yval) < 0 {
 			check.invalidOp(y, _InvalidShiftCount, "negative shift count %s", y)
 			x.mode = invalid
 			return
 		}
+
+		if isUntyped(y.typ) {
+			// Caution: Check for representability here, rather than in the switch
+			// below, because isInteger includes untyped integers (was bug #43697).
+			check.representable(y, Typ[Uint])
+			if y.mode == invalid {
+				x.mode = invalid
+				return
+			}
+		}
 	}
 
-	// Caution: Check for isUntyped first because isInteger includes untyped
+	// Check that RHS is otherwise at least of integer type.
-	//          integers (was bug #43697).
+	switch {
-	if isUntyped(y.typ) {
+	case isInteger(y.typ):
+		if !isUnsigned(y.typ) && !check.allowVersion(check.pkg, 1, 13) {
+			check.invalidOp(y, _InvalidShiftCount, "signed shift count %s requires go1.13 or later", y)
+			x.mode = invalid
+			return
+		}
+	case isUntyped(y.typ):
+		// This is incorrect, but preserves pre-existing behavior.
+		// See also bug #47410.
 		check.convertUntyped(y, Typ[Uint])
 		if y.mode == invalid {
 			x.mode = invalid
 			return
 		}
-	} else if !isInteger(y.typ) {
+	default:
 		check.invalidOp(y, _InvalidShiftCount, "shift count %s must be integer", y)
 		x.mode = invalid
 		return
-	} else if !isUnsigned(y.typ) && !check.allowVersion(check.pkg, 1, 13) {
-		check.invalidOp(y, _InvalidShiftCount, "signed shift count %s requires go1.13 or later", y)
-		x.mode = invalid
-		return
 	}
 
 	if x.mode == constant_ {

src/internal/reflectlite/type.go

@@ -68,7 +68,7 @@ type Type interface {
 }
 
 /*
- * These data structures are known to the compiler (../../cmd/internal/gc/reflect.go).
+ * These data structures are known to the compiler (../../cmd/internal/reflectdata/reflect.go).
  * A few are known to ../runtime/type.go to convey to debuggers.
  * They are also known to ../runtime/type.go.
  */
@@ -111,7 +111,7 @@ const (
 // available in the memory directly following the rtype value.
 //
 // tflag values must be kept in sync with copies in:
-//	cmd/compile/internal/gc/reflect.go
+//	cmd/compile/internal/reflectdata/reflect.go
 //	cmd/link/internal/ld/decodesym.go
 //	runtime/type.go
 type tflag uint8

src/net/dnsclient_unix_test.go

@@ -1846,6 +1846,17 @@ func TestCVE202133195(t *testing.T) {
 							Target: dnsmessage.MustNewName("<html>.golang.org."),
 						},
 					},
+					dnsmessage.Resource{
+						Header: dnsmessage.ResourceHeader{
+							Name:   n,
+							Type:   dnsmessage.TypeSRV,
+							Class:  dnsmessage.ClassINET,
+							Length: 4,
+						},
+						Body: &dnsmessage.SRVResource{
+							Target: dnsmessage.MustNewName("good.golang.org."),
+						},
+					},
 				)
 			case dnsmessage.TypeMX:
 				r.Answers = append(r.Answers,
@@ -1860,6 +1871,17 @@ func TestCVE202133195(t *testing.T) {
 							MX: dnsmessage.MustNewName("<html>.golang.org."),
 						},
 					},
+					dnsmessage.Resource{
+						Header: dnsmessage.ResourceHeader{
+							Name:   dnsmessage.MustNewName("good.golang.org."),
+							Type:   dnsmessage.TypeMX,
+							Class:  dnsmessage.ClassINET,
+							Length: 4,
+						},
+						Body: &dnsmessage.MXResource{
+							MX: dnsmessage.MustNewName("good.golang.org."),
+						},
+					},
 				)
 			case dnsmessage.TypeNS:
 				r.Answers = append(r.Answers,
@@ -1874,6 +1896,17 @@ func TestCVE202133195(t *testing.T) {
 							NS: dnsmessage.MustNewName("<html>.golang.org."),
 						},
 					},
+					dnsmessage.Resource{
+						Header: dnsmessage.ResourceHeader{
+							Name:   dnsmessage.MustNewName("good.golang.org."),
+							Type:   dnsmessage.TypeNS,
+							Class:  dnsmessage.ClassINET,
+							Length: 4,
+						},
+						Body: &dnsmessage.NSResource{
+							NS: dnsmessage.MustNewName("good.golang.org."),
+						},
+					},
 				)
 			case dnsmessage.TypePTR:
 				r.Answers = append(r.Answers,
@@ -1888,6 +1921,17 @@ func TestCVE202133195(t *testing.T) {
 							PTR: dnsmessage.MustNewName("<html>.golang.org."),
 						},
 					},
+					dnsmessage.Resource{
+						Header: dnsmessage.ResourceHeader{
+							Name:   dnsmessage.MustNewName("good.golang.org."),
+							Type:   dnsmessage.TypePTR,
+							Class:  dnsmessage.ClassINET,
+							Length: 4,
+						},
+						Body: &dnsmessage.PTRResource{
+							PTR: dnsmessage.MustNewName("good.golang.org."),
+						},
+					},
 				)
 			}
 			return r, nil
@@ -1903,25 +1947,53 @@ func TestCVE202133195(t *testing.T) {
 	defer func(orig string) { testHookHostsPath = orig }(testHookHostsPath)
 	testHookHostsPath = "testdata/hosts"
 
+	tests := []struct {
+		name string
+		f    func(*testing.T)
+	}{
+		{
+			name: "CNAME",
+			f: func(t *testing.T) {
+				expectedErr := &DNSError{Err: errMalformedDNSRecordsDetail, Name: "golang.org"}
 				_, err := r.LookupCNAME(context.Background(), "golang.org")
-	if expected := "lookup golang.org: CNAME target is invalid"; err == nil || err.Error() != expected {
+				if err.Error() != expectedErr.Error() {
-		t.Errorf("Resolver.LookupCNAME returned unexpected error, got %q, want %q", err, expected)
+					t.Fatalf("unexpected error: %s", err)
 				}
 				_, err = LookupCNAME("golang.org")
-	if expected := "lookup golang.org: CNAME target is invalid"; err == nil || err.Error() != expected {
+				if err.Error() != expectedErr.Error() {
-		t.Errorf("LookupCNAME returned unexpected error, got %q, want %q", err, expected)
+					t.Fatalf("unexpected error: %s", err)
 				}
-
+			},
-	_, _, err = r.LookupSRV(context.Background(), "target", "tcp", "golang.org")
+		},
-	if expected := "lookup golang.org: SRV target is invalid"; err == nil || err.Error() != expected {
+		{
-		t.Errorf("Resolver.LookupSRV returned unexpected error, got %q, want %q", err, expected)
+			name: "SRV (bad record)",
+			f: func(t *testing.T) {
+				expected := []*SRV{
+					{
+						Target: "good.golang.org.",
+					},
 				}
-	_, _, err = LookupSRV("target", "tcp", "golang.org")
+				expectedErr := &DNSError{Err: errMalformedDNSRecordsDetail, Name: "golang.org"}
-	if expected := "lookup golang.org: SRV target is invalid"; err == nil || err.Error() != expected {
+				_, records, err := r.LookupSRV(context.Background(), "target", "tcp", "golang.org")
-		t.Errorf("LookupSRV returned unexpected error, got %q, want %q", err, expected)
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
 				}
-
+				if !reflect.DeepEqual(records, expected) {
-	_, _, err = r.LookupSRV(context.Background(), "hdr", "tcp", "golang.org.")
+					t.Error("Unexpected record set")
+				}
+				_, records, err = LookupSRV("target", "tcp", "golang.org")
+				if err.Error() != expectedErr.Error() {
+					t.Errorf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+			},
+		},
+		{
+			name: "SRV (bad header)",
+			f: func(t *testing.T) {
+				_, _, err := r.LookupSRV(context.Background(), "hdr", "tcp", "golang.org.")
 				if expected := "lookup golang.org.: SRV header name is invalid"; err == nil || err.Error() != expected {
 					t.Errorf("Resolver.LookupSRV returned unexpected error, got %q, want %q", err, expected)
 				}
@@ -1929,33 +2001,85 @@ func TestCVE202133195(t *testing.T) {
 				if expected := "lookup golang.org.: SRV header name is invalid"; err == nil || err.Error() != expected {
 					t.Errorf("LookupSRV returned unexpected error, got %q, want %q", err, expected)
 				}
-
+			},
-	_, err = r.LookupMX(context.Background(), "golang.org")
+		},
-	if expected := "lookup golang.org: MX target is invalid"; err == nil || err.Error() != expected {
+		{
-		t.Errorf("Resolver.LookupMX returned unexpected error, got %q, want %q", err, expected)
+			name: "MX",
+			f: func(t *testing.T) {
+				expected := []*MX{
+					{
+						Host: "good.golang.org.",
+					},
 				}
-	_, err = LookupMX("golang.org")
+				expectedErr := &DNSError{Err: errMalformedDNSRecordsDetail, Name: "golang.org"}
-	if expected := "lookup golang.org: MX target is invalid"; err == nil || err.Error() != expected {
+				records, err := r.LookupMX(context.Background(), "golang.org")
-		t.Errorf("LookupMX returned unexpected error, got %q, want %q", err, expected)
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+				records, err = LookupMX("golang.org")
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+			},
+		},
+		{
+			name: "NS",
+			f: func(t *testing.T) {
+				expected := []*NS{
+					{
+						Host: "good.golang.org.",
+					},
+				}
+				expectedErr := &DNSError{Err: errMalformedDNSRecordsDetail, Name: "golang.org"}
+				records, err := r.LookupNS(context.Background(), "golang.org")
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+				records, err = LookupNS("golang.org")
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+			},
+		},
+		{
+			name: "Addr",
+			f: func(t *testing.T) {
+				expected := []string{"good.golang.org."}
+				expectedErr := &DNSError{Err: errMalformedDNSRecordsDetail, Name: "192.0.2.42"}
+				records, err := r.LookupAddr(context.Background(), "192.0.2.42")
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+				records, err = LookupAddr("192.0.2.42")
+				if err.Error() != expectedErr.Error() {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				if !reflect.DeepEqual(records, expected) {
+					t.Error("Unexpected record set")
+				}
+			},
+		},
 	}
 
-	_, err = r.LookupNS(context.Background(), "golang.org")
+	for _, tc := range tests {
-	if expected := "lookup golang.org: NS target is invalid"; err == nil || err.Error() != expected {
+		t.Run(tc.name, tc.f)
-		t.Errorf("Resolver.LookupNS returned unexpected error, got %q, want %q", err, expected)
-	}
-	_, err = LookupNS("golang.org")
-	if expected := "lookup golang.org: NS target is invalid"; err == nil || err.Error() != expected {
-		t.Errorf("LookupNS returned unexpected error, got %q, want %q", err, expected)
 	}
 
-	_, err = r.LookupAddr(context.Background(), "192.0.2.42")
-	if expected := "lookup 192.0.2.42: PTR target is invalid"; err == nil || err.Error() != expected {
-		t.Errorf("Resolver.LookupAddr returned unexpected error, got %q, want %q", err, expected)
-	}
-	_, err = LookupAddr("192.0.2.42")
-	if expected := "lookup 192.0.2.42: PTR target is invalid"; err == nil || err.Error() != expected {
-		t.Errorf("LookupAddr returned unexpected error, got %q, want %q", err, expected)
-	}
 }
 
 func TestNullMX(t *testing.T) {

src/net/http/client.go

@@ -951,7 +951,7 @@ func (c *Client) CloseIdleConnections() {
 }
 
 // cancelTimerBody is an io.ReadCloser that wraps rc with two features:
-// 1) on Read error or close, the stop func is called.
+// 1) On Read error or close, the stop func is called.
 // 2) On Read failure, if reqDidTimeout is true, the error is wrapped and
 //    marked as net.Error that hit its timeout.
 type cancelTimerBody struct {

src/net/lookup.go

@@ -424,7 +424,7 @@ func (r *Resolver) LookupCNAME(ctx context.Context, host string) (string, error)
 		return "", err
 	}
 	if !isDomainName(cname) {
-		return "", &DNSError{Err: "CNAME target is invalid", Name: host}
+		return "", &DNSError{Err: errMalformedDNSRecordsDetail, Name: host}
 	}
 	return cname, nil
 }
@@ -440,7 +440,9 @@ func (r *Resolver) LookupCNAME(ctx context.Context, host string) (string, error)
 // and proto are empty strings, LookupSRV looks up name directly.
 //
 // The returned service names are validated to be properly
-// formatted presentation-format domain names.
+// formatted presentation-format domain names. If the response contains
+// invalid names, those records are filtered out and an error
+// will be returned alongside the the remaining results, if any.
 func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
 	return DefaultResolver.LookupSRV(context.Background(), service, proto, name)
 }
@@ -456,7 +458,9 @@ func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err err
 // and proto are empty strings, LookupSRV looks up name directly.
 //
 // The returned service names are validated to be properly
-// formatted presentation-format domain names.
+// formatted presentation-format domain names. If the response contains
+// invalid names, those records are filtered out and an error
+// will be returned alongside the the remaining results, if any.
 func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
 	cname, addrs, err := r.lookupSRV(ctx, service, proto, name)
 	if err != nil {
@@ -465,21 +469,28 @@ func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (
 	if cname != "" && !isDomainName(cname) {
 		return "", nil, &DNSError{Err: "SRV header name is invalid", Name: name}
 	}
+	filteredAddrs := make([]*SRV, 0, len(addrs))
 	for _, addr := range addrs {
 		if addr == nil {
 			continue
 		}
 		if !isDomainName(addr.Target) {
-			return "", nil, &DNSError{Err: "SRV target is invalid", Name: name}
+			continue
 		}
+		filteredAddrs = append(filteredAddrs, addr)
 	}
-	return cname, addrs, nil
+	if len(addrs) != len(filteredAddrs) {
+		return cname, filteredAddrs, &DNSError{Err: errMalformedDNSRecordsDetail, Name: name}
+	}
+	return cname, filteredAddrs, nil
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
 //
 // The returned mail server names are validated to be properly
-// formatted presentation-format domain names.
+// formatted presentation-format domain names. If the response contains
+// invalid names, those records are filtered out and an error
+// will be returned alongside the the remaining results, if any.
 //
 // LookupMX uses context.Background internally; to specify the context, use
 // Resolver.LookupMX.
@@ -490,12 +501,15 @@ func LookupMX(name string) ([]*MX, error) {
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
 //
 // The returned mail server names are validated to be properly
-// formatted presentation-format domain names.
+// formatted presentation-format domain names. If the response contains
+// invalid names, those records are filtered out and an error
+// will be returned alongside the the remaining results, if any.
 func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*MX, error) {
 	records, err := r.lookupMX(ctx, name)
 	if err != nil {
 		return nil, err
 	}
+	filteredMX := make([]*MX, 0, len(records))
 	for _, mx := range records {
 		if mx == nil {
 			continue
@@ -503,16 +517,22 @@ func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*MX, error) {
 		// Bypass the hostname validity check for targets which contain only a dot,
 		// as this is used to represent a 'Null' MX record.
 		if mx.Host != "." && !isDomainName(mx.Host) {
-			return nil, &DNSError{Err: "MX target is invalid", Name: name}
+			continue
 		}
+		filteredMX = append(filteredMX, mx)
 	}
-	return records, nil
+	if len(records) != len(filteredMX) {
+		return filteredMX, &DNSError{Err: errMalformedDNSRecordsDetail, Name: name}
+	}
+	return filteredMX, nil
 }
 
 // LookupNS returns the DNS NS records for the given domain name.
 //
 // The returned name server names are validated to be properly
-// formatted presentation-format domain names.
+// formatted presentation-format domain names. If the response contains
+// invalid names, those records are filtered out and an error
+// will be returned alongside the the remaining results, if any.
 //
 // LookupNS uses context.Background internally; to specify the context, use
 // Resolver.LookupNS.
@@ -523,21 +543,28 @@ func LookupNS(name string) ([]*NS, error) {
 // LookupNS returns the DNS NS records for the given domain name.
 //
 // The returned name server names are validated to be properly
-// formatted presentation-format domain names.
+// formatted presentation-format domain names. If the response contains
+// invalid names, those records are filtered out and an error
+// will be returned alongside the the remaining results, if any.
 func (r *Resolver) LookupNS(ctx context.Context, name string) ([]*NS, error) {
 	records, err := r.lookupNS(ctx, name)
 	if err != nil {
 		return nil, err
 	}
+	filteredNS := make([]*NS, 0, len(records))
 	for _, ns := range records {
 		if ns == nil {
 			continue
 		}
 		if !isDomainName(ns.Host) {
-			return nil, &DNSError{Err: "NS target is invalid", Name: name}
+			continue
 		}
+		filteredNS = append(filteredNS, ns)
 	}
-	return records, nil
+	if len(records) != len(filteredNS) {
+		return filteredNS, &DNSError{Err: errMalformedDNSRecordsDetail, Name: name}
+	}
+	return filteredNS, nil
 }
 
 // LookupTXT returns the DNS TXT records for the given domain name.
@@ -557,7 +584,8 @@ func (r *Resolver) LookupTXT(ctx context.Context, name string) ([]string, error)
 // of names mapping to that address.
 //
 // The returned names are validated to be properly formatted presentation-format
-// domain names.
+// domain names. If the response contains invalid names, those records are filtered
+// out and an error will be returned alongside the the remaining results, if any.
 //
 // When using the host C library resolver, at most one result will be
 // returned. To bypass the host resolver, use a custom Resolver.
@@ -572,16 +600,26 @@ func LookupAddr(addr string) (names []string, err error) {
 // of names mapping to that address.
 //
 // The returned names are validated to be properly formatted presentation-format
-// domain names.
+// domain names. If the response contains invalid names, those records are filtered
+// out and an error will be returned alongside the the remaining results, if any.
 func (r *Resolver) LookupAddr(ctx context.Context, addr string) ([]string, error) {
 	names, err := r.lookupAddr(ctx, addr)
 	if err != nil {
 		return nil, err
 	}
+	filteredNames := make([]string, 0, len(names))
 	for _, name := range names {
-		if !isDomainName(name) {
+		if isDomainName(name) {
-			return nil, &DNSError{Err: "PTR target is invalid", Name: addr}
+			filteredNames = append(filteredNames, name)
 		}
 	}
-	return names, nil
+	if len(names) != len(filteredNames) {
+		return filteredNames, &DNSError{Err: errMalformedDNSRecordsDetail, Name: addr}
 	}
+	return filteredNames, nil
+}
+
+// errMalformedDNSRecordsDetail is the DNSError detail which is returned when a Resolver.Lookup...
+// method recieves DNS records which contain invalid DNS names. This may be returned alongside
+// results which have had the malformed records filtered out.
+var errMalformedDNSRecordsDetail = "DNS response contained records which contain invalid names"

src/reflect/all_test.go

@@ -4304,6 +4304,9 @@ func TestConvert(t *testing.T) {
 
 		// vout1 represents the in value converted to the in type.
 		v1 := tt.in
+		if !v1.CanConvert(t1) {
+			t.Errorf("ValueOf(%T(%[1]v)).CanConvert(%s) = false, want true", tt.in.Interface(), t1)
+		}
 		vout1 := v1.Convert(t1)
 		out1 := vout1.Interface()
 		if vout1.Type() != tt.in.Type() || !DeepEqual(out1, tt.in.Interface()) {
@@ -4311,6 +4314,9 @@ func TestConvert(t *testing.T) {
 		}
 
 		// vout2 represents the in value converted to the out type.
+		if !v1.CanConvert(t2) {
+			t.Errorf("ValueOf(%T(%[1]v)).CanConvert(%s) = false, want true", tt.in.Interface(), t2)
+		}
 		vout2 := v1.Convert(t2)
 		out2 := vout2.Interface()
 		if vout2.Type() != tt.out.Type() || !DeepEqual(out2, tt.out.Interface()) {
@@ -4371,6 +4377,9 @@ func TestConvertPanic(t *testing.T) {
 	if !v.Type().ConvertibleTo(pt) {
 		t.Errorf("[]byte should be convertible to *[8]byte")
 	}
+	if v.CanConvert(pt) {
+		t.Errorf("slice with length 4 should not be convertible to *[8]byte")
+	}
 	shouldPanic("reflect: cannot convert slice with length 4 to pointer to array with length 8", func() {
 		_ = v.Convert(pt)
 	})

src/reflect/type.go

@@ -228,7 +228,7 @@ type Type interface {
 // See https://golang.org/issue/4876 for more details.
 
 /*
- * These data structures are known to the compiler (../../cmd/internal/gc/reflect.go).
+ * These data structures are known to the compiler (../../cmd/internal/reflectdata/reflect.go).
  * A few are known to ../runtime/type.go to convey to debuggers.
  * They are also known to ../runtime/type.go.
  */
@@ -271,7 +271,7 @@ const (
 // available in the memory directly following the rtype value.
 //
 // tflag values must be kept in sync with copies in:
-//	cmd/compile/internal/gc/reflect.go
+//	cmd/compile/internal/reflectdata/reflect.go
 //	cmd/link/internal/ld/decodesym.go
 //	runtime/type.go
 type tflag uint8
@@ -1910,7 +1910,7 @@ func MapOf(key, elem Type) Type {
 
 	// Make a map type.
 	// Note: flag values must match those used in the TMAP case
-	// in ../cmd/compile/internal/gc/reflect.go:writeType.
+	// in ../cmd/compile/internal/reflectdata/reflect.go:writeType.
 	var imap interface{} = (map[unsafe.Pointer]unsafe.Pointer)(nil)
 	mt := **(**mapType)(unsafe.Pointer(&imap))
 	mt.str = resolveReflectName(newName(s, "", false))
@@ -2841,7 +2841,7 @@ func runtimeStructField(field StructField) (structField, string) {
 
 // typeptrdata returns the length in bytes of the prefix of t
 // containing pointer data. Anything after this offset is scalar data.
-// keep in sync with ../cmd/compile/internal/gc/reflect.go
+// keep in sync with ../cmd/compile/internal/reflectdata/reflect.go
 func typeptrdata(t *rtype) uintptr {
 	switch t.Kind() {
 	case Struct:
@@ -2865,7 +2865,7 @@ func typeptrdata(t *rtype) uintptr {
 	}
 }
 
-// See cmd/compile/internal/gc/reflect.go for derivation of constant.
+// See cmd/compile/internal/reflectdata/reflect.go for derivation of constant.
 const maxPtrmaskBytes = 2048
 
 // ArrayOf returns the array type with the given length and element type.

src/reflect/value.go

@@ -2811,6 +2811,26 @@ func (v Value) Convert(t Type) Value {
 	return op(v, t)
 }
 
+// CanConvert reports whether the value v can be converted to type t.
+// If v.CanConvert(t) returns true then v.Convert(t) will not panic.
+func (v Value) CanConvert(t Type) bool {
+	vt := v.Type()
+	if !vt.ConvertibleTo(t) {
+		return false
+	}
+	// Currently the only conversion that is OK in terms of type
+	// but that can panic depending on the value is converting
+	// from slice to pointer-to-array.
+	if vt.Kind() == Slice && t.Kind() == Ptr && t.Elem().Kind() == Array {
+		n := t.Elem().Len()
+		h := (*unsafeheader.Slice)(v.ptr)
+		if n > h.Len {
+			return false
+		}
+	}
+	return true
+}
+
 // convertOp returns the function to convert a value of type src
 // to a value of type dst. If the conversion is illegal, convertOp returns nil.
 func convertOp(dst, src *rtype) func(Value, Type) Value {

src/reflect/visiblefields.go

@@ -1,3 +1,7 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package reflect
 
 // VisibleFields returns all the visible fields in t, which must be a

src/reflect/visiblefields_test.go

@@ -1,3 +1,7 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package reflect_test
 
 import (

src/runtime/checkptr.go

@@ -7,6 +7,11 @@ package runtime
 import "unsafe"
 
 func checkptrAlignment(p unsafe.Pointer, elem *_type, n uintptr) {
+	// nil pointer is always suitably aligned (#47430).
+	if p == nil {
+		return
+	}
+
 	// Check that (*[n]elem)(p) is appropriately aligned.
 	// Note that we allow unaligned pointers if the types they point to contain
 	// no pointers themselves. See issue 37298.
@@ -29,10 +34,12 @@ func checkptrStraddles(ptr unsafe.Pointer, size uintptr) bool {
 		return false
 	}
 
-	end := add(ptr, size-1)
+	// Check that add(ptr, size-1) won't overflow. This avoids the risk
-	if uintptr(end) < uintptr(ptr) {
+	// of producing an illegal pointer value (assuming ptr is legal).
+	if uintptr(ptr) >= -(size - 1) {
 		return true
 	}
+	end := add(ptr, size-1)
 
 	// TODO(mdempsky): Detect when [ptr, end] contains Go allocations,
 	// but neither ptr nor end point into one themselves.

src/runtime/checkptr_test.go

@@ -26,6 +26,7 @@ func TestCheckPtr(t *testing.T) {
 	}{
 		{"CheckPtrAlignmentPtr", "fatal error: checkptr: misaligned pointer conversion\n"},
 		{"CheckPtrAlignmentNoPtr", ""},
+		{"CheckPtrAlignmentNilPtr", ""},
 		{"CheckPtrArithmetic", "fatal error: checkptr: pointer arithmetic result points to invalid allocation\n"},
 		{"CheckPtrArithmetic2", "fatal error: checkptr: pointer arithmetic result points to invalid allocation\n"},
 		{"CheckPtrSize", "fatal error: checkptr: converted pointer straddles multiple allocations\n"},

src/runtime/debug/panic_test.go

@@ -24,6 +24,9 @@ func TestPanicOnFault(t *testing.T) {
 	if runtime.GOOS == "ios" {
 		t.Skip("iOS doesn't provide fault addresses")
 	}
+	if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm" {
+		t.Skip("netbsd-arm doesn't provide fault address (golang.org/issue/45026)")
+	}
 	m, err := syscall.Mmap(-1, 0, 0x1000, syscall.PROT_READ /* Note: no PROT_WRITE */, syscall.MAP_SHARED|syscall.MAP_ANON)
 	if err != nil {
 		t.Fatalf("can't map anonymous memory: %s", err)

src/runtime/internal/sys/zgoarch_386.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_amd64.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_arm.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_arm64.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 1
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_arm64be.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 1
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_armbe.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_loong64.go

@@ -0,0 +1,33 @@
+// Code generated by gengoos.go using 'go generate'. DO NOT EDIT.
+
+//go:build loong64
+// +build loong64
+
+package sys
+
+const GOARCH = `loong64`
+
+const Goarch386 = 0
+const GoarchAmd64 = 0
+const GoarchAmd64p32 = 0
+const GoarchArm = 0
+const GoarchArmbe = 0
+const GoarchArm64 = 0
+const GoarchArm64be = 0
+const GoarchPpc64 = 0
+const GoarchPpc64le = 0
+const GoarchLoong64 = 1
+const GoarchMips = 0
+const GoarchMipsle = 0
+const GoarchMips64 = 0
+const GoarchMips64le = 0
+const GoarchMips64p32 = 0
+const GoarchMips64p32le = 0
+const GoarchPpc = 0
+const GoarchRiscv = 0
+const GoarchRiscv64 = 0
+const GoarchS390 = 0
+const GoarchS390x = 0
+const GoarchSparc = 0
+const GoarchSparc64 = 0
+const GoarchWasm = 0

src/runtime/internal/sys/zgoarch_mips.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 1
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_mips64.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 1

src/runtime/internal/sys/zgoarch_mips64le.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_mips64p32.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_mips64p32le.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_mipsle.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 1
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_ppc.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_ppc64.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 1
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_ppc64le.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 1
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_riscv.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_riscv64.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_s390.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_s390x.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_sparc.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_sparc64.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/internal/sys/zgoarch_wasm.go

@@ -16,6 +16,7 @@ const GoarchArm64 = 0
 const GoarchArm64be = 0
 const GoarchPpc64 = 0
 const GoarchPpc64le = 0
+const GoarchLoong64 = 0
 const GoarchMips = 0
 const GoarchMipsle = 0
 const GoarchMips64 = 0

src/runtime/malloc.go

@@ -1135,13 +1135,21 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
 		msanmalloc(x, size)
 	}
 
+	if rate := MemProfileRate; rate > 0 {
+		// Note cache c only valid while m acquired; see #47302
+		if rate != 1 && size < c.nextSample {
+			c.nextSample -= size
+		} else {
+			profilealloc(mp, x, size)
+		}
+	}
 	mp.mallocing = 0
 	releasem(mp)
 
 	// Pointerfree data can be zeroed late in a context where preemption can occur.
 	// x will keep the memory alive.
 	if !isZeroed && needzero {
-		memclrNoHeapPointersChunked(size, x)
+		memclrNoHeapPointersChunked(size, x) // This is a possible preemption point: see #47302
 	}
 
 	if debug.malloc {
@@ -1155,16 +1163,6 @@ func mallocgc(size uintptr, typ *_type, needzero bool) unsafe.Pointer {
 		}
 	}
 
-	if rate := MemProfileRate; rate > 0 {
-		if rate != 1 && size < c.nextSample {
-			c.nextSample -= size
-		} else {
-			mp := acquirem()
-			profilealloc(mp, x, size)
-			releasem(mp)
-		}
-	}
-
 	if assistG != nil {
 		// Account for internal fragmentation in the assist
 		// debt now that we know it.

src/runtime/pprof/mprof_test.go

@@ -86,6 +86,17 @@ func TestMemoryProfiler(t *testing.T) {
 
 	runtime.GC() // materialize stats
 
+	// TODO(mknyszek): Fix #45315 and remove this extra call.
+	//
+	// Unfortunately, it's possible for the sweep termination condition
+	// to flap, so with just one runtime.GC call, a freed object could be
+	// missed, leading this test to fail. A second call reduces the chance
+	// of this happening to zero, because sweeping actually has to finish
+	// to move on to the next GC, during which nothing will happen.
+	//
+	// See #46500 for more details.
+	runtime.GC()
+
 	memoryProfilerRun++
 
 	tests := []struct {

src/runtime/proc.go

@@ -4919,7 +4919,6 @@ func (pp *p) destroy() {
 		moveTimers(plocal, pp.timers)
 		pp.timers = nil
 		pp.numTimers = 0
-		pp.adjustTimers = 0
 		pp.deletedTimers = 0
 		atomic.Store64(&pp.timer0When, 0)
 		unlock(&pp.timersLock)

src/runtime/race.go

@@ -343,7 +343,7 @@ func racereadrangepc1(addr, size, pc uintptr)
 func racewriterangepc1(addr, size, pc uintptr)
 func racecallbackthunk(uintptr)
 
-// racecall allows calling an arbitrary function f from C race runtime
+// racecall allows calling an arbitrary function fn from C race runtime
 // with up to 4 uintptr arguments.
 func racecall(fn *byte, arg0, arg1, arg2, arg3 uintptr)
 

src/runtime/runtime2.go

@@ -681,7 +681,7 @@ type p struct {
 	// timerModifiedEarlier status. Because the timer may have been
 	// modified again, there need not be any timer with this value.
 	// This is updated using atomic functions.
-	// This is 0 if the value is unknown.
+	// This is 0 if there are no timerModifiedEarlier timers.
 	timerModifiedEarliest uint64
 
 	// Per-P GC state
@@ -727,12 +727,6 @@ type p struct {
 	// Modified using atomic instructions.
 	numTimers uint32
 
-	// Number of timerModifiedEarlier timers on P's heap.
-	// This should only be modified while holding timersLock,
-	// or while the timer status is in a transient state
-	// such as timerModifying.
-	adjustTimers uint32
-
 	// Number of timerDeleted timers in P's heap.
 	// Modified using atomic instructions.
 	deletedTimers uint32
@@ -895,7 +889,7 @@ type funcinl struct {
 // layout of Itab known to compilers
 // allocated in non-garbage-collected memory
 // Needs to be in sync with
-// ../cmd/compile/internal/gc/reflect.go:/^func.WriteTabs.
+// ../cmd/compile/internal/reflectdata/reflect.go:/^func.WriteTabs.
 type itab struct {
 	inter *interfacetype
 	_type *_type
@@ -940,7 +934,7 @@ func extendRandom(r []byte, n int) {
 
 // A _defer holds an entry on the list of deferred calls.
 // If you add a field here, add code to clear it in freedefer and deferProcStack
-// This struct must match the code in cmd/compile/internal/gc/reflect.go:deferstruct
+// This struct must match the code in cmd/compile/internal/reflectdata/reflect.go:deferstruct
 // and cmd/compile/internal/gc/ssa.go:(*state).call.
 // Some defers will be allocated on the stack and some on the heap.
 // All defers are logically part of the stack, so write barriers to

src/runtime/select.go

@@ -15,7 +15,7 @@ const debugSelect = false
 
 // Select case descriptor.
 // Known to compiler.
-// Changes here must also be made in src/cmd/internal/gc/select.go's scasetype.
+// Changes here must also be made in src/cmd/compile/internal/walk/select.go's scasetype.
 type scase struct {
 	c    *hchan         // chan
 	elem unsafe.Pointer // data element

src/runtime/testdata/testprog/checkptr.go

@@ -4,11 +4,16 @@
 
 package main
 
-import "unsafe"
+import (
+	"runtime"
+	"time"
+	"unsafe"
+)
 
 func init() {
 	register("CheckPtrAlignmentNoPtr", CheckPtrAlignmentNoPtr)
 	register("CheckPtrAlignmentPtr", CheckPtrAlignmentPtr)
+	register("CheckPtrAlignmentNilPtr", CheckPtrAlignmentNilPtr)
 	register("CheckPtrArithmetic", CheckPtrArithmetic)
 	register("CheckPtrArithmetic2", CheckPtrArithmetic2)
 	register("CheckPtrSize", CheckPtrSize)
@@ -29,6 +34,35 @@ func CheckPtrAlignmentPtr() {
 	sink2 = (**int64)(unsafe.Pointer(uintptr(p) + 1))
 }
 
+// CheckPtrAlignmentNilPtr tests that checkptrAlignment doesn't crash
+// on nil pointers (#47430).
+func CheckPtrAlignmentNilPtr() {
+	var do func(int)
+	do = func(n int) {
+		// Inflate the stack so runtime.shrinkstack gets called during GC
+		if n > 0 {
+			do(n - 1)
+		}
+
+		var p unsafe.Pointer
+		_ = (*int)(p)
+	}
+
+	go func() {
+		for {
+			runtime.GC()
+		}
+	}()
+
+	go func() {
+		for i := 0; ; i++ {
+			do(i % 1024)
+		}
+	}()
+
+	time.Sleep(time.Second)
+}
+
 func CheckPtrArithmetic() {
 	var x int
 	i := uintptr(unsafe.Pointer(&x))

src/runtime/time.go

@@ -333,7 +333,6 @@ func deltimer(t *timer) bool {
 				// Must fetch t.pp before setting status
 				// to timerDeleted.
 				tpp := t.pp.ptr()
-				atomic.Xadd(&tpp.adjustTimers, -1)
 				if !atomic.Cas(&t.status, timerModifying, timerDeleted) {
 					badTimer()
 				}
@@ -510,20 +509,9 @@ loop:
 
 		tpp := t.pp.ptr()
 
-		// Update the adjustTimers field.  Subtract one if we
-		// are removing a timerModifiedEarlier, add one if we
-		// are adding a timerModifiedEarlier.
-		adjust := int32(0)
-		if status == timerModifiedEarlier {
-			adjust--
-		}
 		if newStatus == timerModifiedEarlier {
-			adjust++
 			updateTimerModifiedEarliest(tpp, when)
 		}
-		if adjust != 0 {
-			atomic.Xadd(&tpp.adjustTimers, adjust)
-		}
 
 		// Set the new status of the timer.
 		if !atomic.Cas(&t.status, timerModifying, newStatus) {
@@ -591,9 +579,6 @@ func cleantimers(pp *p) {
 			// Move t to the right position.
 			dodeltimer0(pp)
 			doaddtimer(pp, t)
-			if s == timerModifiedEarlier {
-				atomic.Xadd(&pp.adjustTimers, -1)
-			}
 			if !atomic.Cas(&t.status, timerMoving, timerWaiting) {
 				badTimer()
 			}
@@ -664,25 +649,13 @@ func moveTimers(pp *p, timers []*timer) {
 // it also moves timers that have been modified to run later,
 // and removes deleted timers. The caller must have locked the timers for pp.
 func adjusttimers(pp *p, now int64) {
-	if atomic.Load(&pp.adjustTimers) == 0 {
-		if verifyTimers {
-			verifyTimerHeap(pp)
-		}
-		// There are no timers to adjust, so it is safe to clear
-		// timerModifiedEarliest. Do so in case it is stale.
-		// Everything will work if we don't do this,
-		// but clearing here may save future calls to adjusttimers.
-		atomic.Store64(&pp.timerModifiedEarliest, 0)
-		return
-	}
-
 	// If we haven't yet reached the time of the first timerModifiedEarlier
 	// timer, don't do anything. This speeds up programs that adjust
 	// a lot of timers back and forth if the timers rarely expire.
 	// We'll postpone looking through all the adjusted timers until
 	// one would actually expire.
-	if first := atomic.Load64(&pp.timerModifiedEarliest); first != 0 {
+	first := atomic.Load64(&pp.timerModifiedEarliest)
-		if int64(first) > now {
+	if first == 0 || int64(first) > now {
 		if verifyTimers {
 			verifyTimerHeap(pp)
 		}
@@ -691,10 +664,8 @@ func adjusttimers(pp *p, now int64) {
 
 	// We are going to clear all timerModifiedEarlier timers.
 	atomic.Store64(&pp.timerModifiedEarliest, 0)
-	}
 
 	var moved []*timer
-loop:
 	for i := 0; i < len(pp.timers); i++ {
 		t := pp.timers[i]
 		if t.pp.ptr() != pp {
@@ -721,11 +692,6 @@ loop:
 				// loop to skip some other timer.
 				dodeltimer(pp, i)
 				moved = append(moved, t)
-				if s == timerModifiedEarlier {
-					if n := atomic.Xadd(&pp.adjustTimers, -1); int32(n) <= 0 {
-						break loop
-					}
-				}
 				// Look at this heap position again.
 				i--
 			}
@@ -824,9 +790,6 @@ func runtimer(pp *p, now int64) int64 {
 			t.when = t.nextwhen
 			dodeltimer0(pp)
 			doaddtimer(pp, t)
-			if s == timerModifiedEarlier {
-				atomic.Xadd(&pp.adjustTimers, -1)
-			}
 			if !atomic.Cas(&t.status, timerMoving, timerWaiting) {
 				badTimer()
 			}
@@ -921,7 +884,6 @@ func clearDeletedTimers(pp *p) {
 	atomic.Store64(&pp.timerModifiedEarliest, 0)
 
 	cdel := int32(0)
-	cearlier := int32(0)
 	to := 0
 	changedHeap := false
 	timers := pp.timers
@@ -946,9 +908,6 @@ nextTimer:
 					if !atomic.Cas(&t.status, timerMoving, timerWaiting) {
 						badTimer()
 					}
-					if s == timerModifiedEarlier {
-						cearlier++
-					}
 					continue nextTimer
 				}
 			case timerDeleted:
@@ -985,7 +944,6 @@ nextTimer:
 
 	atomic.Xadd(&pp.deletedTimers, -cdel)
 	atomic.Xadd(&pp.numTimers, -cdel)
-	atomic.Xadd(&pp.adjustTimers, -cearlier)
 
 	timers = timers[:to]
 	pp.timers = timers

src/runtime/traceback_test.go

@@ -19,8 +19,8 @@ func TestTracebackArgs(t *testing.T) {
 	}{
 		// simple ints
 		{
-			func() int { return testTracebackArgs1(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) },
+			func() int { return testTracebackArgs1(1, 2, 3, 4, 5) },
-			"testTracebackArgs1(0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...)",
+			"testTracebackArgs1(0x1, 0x2, 0x3, 0x4, 0x5)",
 		},
 		// some aggregates
 		{
@@ -53,6 +53,58 @@ func TestTracebackArgs(t *testing.T) {
 			},
 			"testTracebackArgs5(0x0, {0x1, {}, {{}, {}}}, {}, {}, {}, {}, {}, ...)",
 		},
+
+		// edge cases for ...
+		// no ... for 10 args
+		{
+			func() int { return testTracebackArgs6a(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) },
+			"testTracebackArgs6a(0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa)",
+		},
+		// has ... for 11 args
+		{
+			func() int { return testTracebackArgs6b(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) },
+			"testTracebackArgs6b(0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...)",
+		},
+		// no ... for aggregates with 10 words
+		{
+			func() int { return testTracebackArgs7a([10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) },
+			"testTracebackArgs7a({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa})",
+		},
+		// has ... for aggregates with 11 words
+		{
+			func() int { return testTracebackArgs7b([11]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}) },
+			"testTracebackArgs7b({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...})",
+		},
+		// no ... for aggregates, but with more args
+		{
+			func() int { return testTracebackArgs7c([10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, 11) },
+			"testTracebackArgs7c({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa}, ...)",
+		},
+		// has ... for aggregates and also for more args
+		{
+			func() int { return testTracebackArgs7d([11]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}, 12) },
+			"testTracebackArgs7d({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, ...}, ...)",
+		},
+		// nested aggregates, no ...
+		{
+			func() int { return testTracebackArgs8a(testArgsType8a{1, 2, 3, 4, 5, 6, 7, 8, [2]int{9, 10}}) },
+			"testTracebackArgs8a({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa}})",
+		},
+		// nested aggregates, ... in inner but not outer
+		{
+			func() int { return testTracebackArgs8b(testArgsType8b{1, 2, 3, 4, 5, 6, 7, 8, [3]int{9, 10, 11}}) },
+			"testTracebackArgs8b({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa, ...}})",
+		},
+		// nested aggregates, ... in outer but not inner
+		{
+			func() int { return testTracebackArgs8c(testArgsType8c{1, 2, 3, 4, 5, 6, 7, 8, [2]int{9, 10}, 11}) },
+			"testTracebackArgs8c({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa}, ...})",
+		},
+		// nested aggregates, ... in both inner and outer
+		{
+			func() int { return testTracebackArgs8d(testArgsType8d{1, 2, 3, 4, 5, 6, 7, 8, [3]int{9, 10, 11}, 12}) },
+			"testTracebackArgs8d({0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, {0x9, 0xa, ...}, ...})",
+		},
 	}
 	for _, test := range tests {
 		n := test.fn()
@@ -64,11 +116,11 @@ func TestTracebackArgs(t *testing.T) {
 }
 
 //go:noinline
-func testTracebackArgs1(a, b, c, d, e, f, g, h, i, j, k, l int) int {
+func testTracebackArgs1(a, b, c, d, e int) int {
 	n := runtime.Stack(testTracebackArgsBuf[:], false)
 	if a < 0 {
 		// use in-reg args to keep them alive
-		return a + b + c + d + e + f + g + h + i + j + k + l
+		return a + b + c + d + e
 	}
 	return n
 }
@@ -119,3 +171,122 @@ func testTracebackArgs5(a bool, x struct {
 	}
 	return n
 }
+
+//go:noinline
+func testTracebackArgs6a(a, b, c, d, e, f, g, h, i, j int) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a < 0 {
+		// use in-reg args to keep them alive
+		return a + b + c + d + e + f + g + h + i + j
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs6b(a, b, c, d, e, f, g, h, i, j, k int) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a < 0 {
+		// use in-reg args to keep them alive
+		return a + b + c + d + e + f + g + h + i + j + k
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs7a(a [10]int) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a[0] < 0 {
+		// use in-reg args to keep them alive
+		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9]
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs7b(a [11]int) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a[0] < 0 {
+		// use in-reg args to keep them alive
+		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9] + a[10]
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs7c(a [10]int, b int) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a[0] < 0 {
+		// use in-reg args to keep them alive
+		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9] + b
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs7d(a [11]int, b int) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a[0] < 0 {
+		// use in-reg args to keep them alive
+		return a[1] + a[2] + a[3] + a[4] + a[5] + a[6] + a[7] + a[8] + a[9] + a[10] + b
+	}
+	return n
+}
+
+type testArgsType8a struct {
+	a, b, c, d, e, f, g, h int
+	i                      [2]int
+}
+type testArgsType8b struct {
+	a, b, c, d, e, f, g, h int
+	i                      [3]int
+}
+type testArgsType8c struct {
+	a, b, c, d, e, f, g, h int
+	i                      [2]int
+	j                      int
+}
+type testArgsType8d struct {
+	a, b, c, d, e, f, g, h int
+	i                      [3]int
+	j                      int
+}
+
+//go:noinline
+func testTracebackArgs8a(a testArgsType8a) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a.a < 0 {
+		// use in-reg args to keep them alive
+		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1]
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs8b(a testArgsType8b) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a.a < 0 {
+		// use in-reg args to keep them alive
+		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1] + a.i[2]
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs8c(a testArgsType8c) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a.a < 0 {
+		// use in-reg args to keep them alive
+		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1] + a.j
+	}
+	return n
+}
+
+//go:noinline
+func testTracebackArgs8d(a testArgsType8d) int {
+	n := runtime.Stack(testTracebackArgsBuf[:], false)
+	if a.a < 0 {
+		// use in-reg args to keep them alive
+		return a.b + a.c + a.d + a.e + a.f + a.g + a.h + a.i[0] + a.i[1] + a.i[2] + a.j
+	}
+	return n
+}

src/runtime/type.go

@@ -11,7 +11,7 @@ import "unsafe"
 // tflag is documented in reflect/type.go.
 //
 // tflag values must be kept in sync with copies in:
-//	cmd/compile/internal/gc/reflect.go
+//	cmd/compile/internal/reflectdata/reflect.go
 //	cmd/link/internal/ld/decodesym.go
 //	reflect/type.go
 //      internal/reflectlite/type.go
@@ -25,7 +25,7 @@ const (
 )
 
 // Needs to be in sync with ../cmd/link/internal/ld/decodesym.go:/^func.commonsize,
-// ../cmd/compile/internal/gc/reflect.go:/^func.dcommontype and
+// ../cmd/compile/internal/reflectdata/reflect.go:/^func.dcommontype and
 // ../reflect/type.go:/^type.rtype.
 // ../internal/reflectlite/type.go:/^type.rtype.
 type _type struct {
@@ -383,7 +383,7 @@ type maptype struct {
 }
 
 // Note: flag values must match those used in the TMAP case
-// in ../cmd/compile/internal/gc/reflect.go:writeType.
+// in ../cmd/compile/internal/reflectdata/reflect.go:writeType.
 func (mt *maptype) indirectkey() bool { // store ptr to key instead of key itself
 	return mt.flags&1 != 0
 }

src/testing/testing.go

@@ -233,6 +233,8 @@
 //		os.Exit(m.Run())
 //	}
 //
+// TestMain is a low-level primitive and should not be necessary for casual
+// testing needs, where ordinary test functions suffice.
 package testing
 
 import (
@@ -678,7 +680,11 @@ type T struct {
 
 func (c *common) private() {}
 
-// Name returns the name of the running test or benchmark.
+// Name returns the name of the running (sub-) test or benchmark.
+//
+// The name will include the name of the test along with the names of
+// any nested sub-tests. If two sibling sub-tests have the same name,
+// Name will append a suffix to guarantee the returned name is unique.
 func (c *common) Name() string {
 	return c.name
 }

src/text/scanner/scanner.go

@@ -23,7 +23,7 @@ import (
 	"unicode/utf8"
 )
 
-// A source position is represented by a Position value.
+// Position is a value that represents a source position.
 // A position is valid if Line > 0.
 type Position struct {
 	Filename string // filename, if any

src/time/sleep_test.go

@@ -527,6 +527,40 @@ func TestZeroTimer(t *testing.T) {
 	}
 }
 
+// Test that rapidly moving a timer earlier doesn't cause it to get dropped.
+// Issue 47329.
+func TestTimerModifiedEarlier(t *testing.T) {
+	past := Until(Unix(0, 0))
+	count := 1000
+	fail := 0
+	for i := 0; i < count; i++ {
+		timer := NewTimer(Hour)
+		for j := 0; j < 10; j++ {
+			if !timer.Stop() {
+				<-timer.C
+			}
+			timer.Reset(past)
+		}
+
+		deadline := NewTimer(10 * Second)
+		defer deadline.Stop()
+		now := Now()
+		select {
+		case <-timer.C:
+			if since := Since(now); since > 8*Second {
+				t.Errorf("timer took too long (%v)", since)
+				fail++
+			}
+		case <-deadline.C:
+			t.Error("deadline expired")
+		}
+	}
+
+	if fail > 0 {
+		t.Errorf("%d failures", fail)
+	}
+}
+
 // Benchmark timer latency when the thread that creates the timer is busy with
 // other work and the timers must be serviced by other threads.
 // https://golang.org/issue/38860

src/time/time.go

@@ -1334,7 +1334,7 @@ func UnixMilli(msec int64) Time {
 }
 
 // UnixMicro returns the local Time corresponding to the given Unix time,
-// usec milliseconds since January 1, 1970 UTC.
+// usec microseconds since January 1, 1970 UTC.
 func UnixMicro(usec int64) Time {
 	return Unix(usec/1e6, (usec%1e6)*1e3)
 }

test/bench/go1/regexp_test.go

@@ -53,7 +53,7 @@ func BenchmarkRegexpMatchEasy0_32(b *testing.B)  { benchmark(b, easy0, 32<<0) }
 func BenchmarkRegexpMatchEasy0_1K(b *testing.B)  { benchmark(b, easy0, 1<<10) }
 func BenchmarkRegexpMatchEasy1_32(b *testing.B)  { benchmark(b, easy1, 32<<0) }
 func BenchmarkRegexpMatchEasy1_1K(b *testing.B)  { benchmark(b, easy1, 1<<10) }
-func BenchmarkRegexpMatchMedium_32(b *testing.B) { benchmark(b, medium, 1<<0) }
+func BenchmarkRegexpMatchMedium_32(b *testing.B) { benchmark(b, medium, 32<<0) }
 func BenchmarkRegexpMatchMedium_1K(b *testing.B) { benchmark(b, medium, 1<<10) }
 func BenchmarkRegexpMatchHard_32(b *testing.B)   { benchmark(b, hard, 32<<0) }
 func BenchmarkRegexpMatchHard_1K(b *testing.B)   { benchmark(b, hard, 1<<10) }

test/fixedbugs/issue47087.dir/a.go

@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func F() interface{} { return struct{ _ []int }{} }
+
+var X = F()

test/fixedbugs/issue47087.dir/b.go

@@ -0,0 +1,9 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+func F() interface{} { return struct{ _ []int }{} }
+
+var X = F()

test/fixedbugs/issue47087.dir/main.go

@@ -0,0 +1,19 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"a"
+	"b"
+)
+
+func main() {
+	if a.F() == b.F() {
+		panic("FAIL")
+	}
+	if a.X == b.X {
+		panic("FAIL")
+	}
+}

test/fixedbugs/issue47087.go

@@ -0,0 +1,7 @@
+// rundir
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ignored