Merge pull request #93 from microsoft-golang-bot/auto-merge/microsoft…

…/main

[`microsoft/main`] Merge upstream `master`

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of Apr 28, 2021",
+	"Subtitle": "Version of Jun 2, 2021",
 	"Path": "/ref/spec"
 }-->
 
@@ -4909,7 +4909,7 @@ <h3 id="Switch_statements">Switch statements</h3>
 
 <p>
 "Switch" statements provide multi-way execution.
-An expression or type specifier is compared to the "cases"
+An expression or type is compared to the "cases"
 inside the "switch" to determine which branch
 to execute.
 </p>
@@ -5020,7 +5020,7 @@ <h4 id="Type_switches">Type switches</h4>
 A type switch compares types rather than values. It is otherwise similar
 to an expression switch. It is marked by a special switch expression that
 has the form of a <a href="#Type_assertions">type assertion</a>
-using the reserved word <code>type</code> rather than an actual type:
+using the keyword <code>type</code> rather than an actual type:
 </p>
 
 <pre>

misc/cgo/errors/errors_test.go

@@ -40,7 +40,8 @@ func check(t *testing.T, file string) {
 			if len(frags) == 1 {
 				continue
 			}
-			re, err := regexp.Compile(string(frags[1]))
+			frag := fmt.Sprintf(":%d:.*%s", i+1, frags[1])
+			re, err := regexp.Compile(frag)
 			if err != nil {
 				t.Errorf("Invalid regexp after `ERROR HERE: `: %#q", frags[1])
 				continue

misc/cgo/errors/testdata/err2.go

@@ -40,15 +40,15 @@ func main() {
 	C.foop = x // ERROR HERE
 
 	// issue 13129: used to output error about C.unsignedshort with CC=clang
-	var x C.ushort
-	x = int(0) // ERROR HERE: C\.ushort
+	var x1 C.ushort
+	x1 = int(0) // ERROR HERE: C\.ushort
 
 	// issue 13423
 	_ = C.fopen() // ERROR HERE
 
 	// issue 13467
-	var x rune = '✈'
-	var _ rune = C.transform(x) // ERROR HERE: C\.int
+	var x2 rune = '✈'
+	var _ rune = C.transform(x2) // ERROR HERE: C\.int
 
 	// issue 13635: used to output error about C.unsignedchar.
 	// This test tests all such types.
@@ -91,10 +91,10 @@ func main() {
 
 	// issue 26745
 	_ = func(i int) int {
-		return C.i + 1 // ERROR HERE: :13
+		return C.i + 1 // ERROR HERE: 14
 	}
 	_ = func(i int) {
-		C.fi(i) // ERROR HERE: :6
+		C.fi(i) // ERROR HERE: 7
 	}
 
 	C.fi = C.fi // ERROR HERE

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

@@ -449,7 +449,7 @@ func (config *ABIConfig) ABIAnalyze(t *types.Type, setNname bool) *ABIParamResul
 // parameterUpdateMu protects the Offset field of function/method parameters (a subset of structure Fields)
 var parameterUpdateMu sync.Mutex
 
-// FieldOffsetOf returns a concurency-safe version of f.Offset
+// FieldOffsetOf returns a concurrency-safe version of f.Offset
 func FieldOffsetOf(f *types.Field) int64 {
 	parameterUpdateMu.Lock()
 	defer parameterUpdateMu.Unlock()

src/crypto/elliptic/elliptic.go

@@ -455,7 +455,7 @@ func initP384() {
 // Multiple invocations of this function will return the same value, so it can
 // be used for equality checks and switch statements.
 //
-// The cryptographic operations are implemented using constant-time algorithms.
+// ScalarMult and ScalarBaseMult are implemented using constant-time algorithms.
 func P256() Curve {
 	initonce.Do(initAll)
 	return p256
@@ -479,7 +479,7 @@ func P384() Curve {
 // Multiple invocations of this function will return the same value, so it can
 // be used for equality checks and switch statements.
 //
-// The cryptographic operations do not use constant-time algorithms.
+// The cryptographic operations are implemented using constant-time algorithms.
 func P521() Curve {
 	initonce.Do(initAll)
 	return p521

src/crypto/tls/common.go

@@ -619,7 +619,7 @@ type Config struct {
 	// protocol will be one from this list, and the connection will fail
 	// if there is no mutually supported protocol. If NextProtos is empty
 	// or the peer doesn't support ALPN, the connection will succeed and
-	// ConnectionState.NegotiatedProtocol will be empty."
+	// ConnectionState.NegotiatedProtocol will be empty.
 	NextProtos []string
 
 	// ServerName is used to verify the hostname on the returned

src/fmt/doc.go

@@ -189,7 +189,7 @@
 	When printing a struct, fmt cannot and therefore does not invoke
 	formatting methods such as Error or String on unexported fields.
 
-	Explicit argument indexes:
+	Explicit argument indexes
 
 	In Printf, Sprintf, and Fprintf, the default behavior is for each
 	formatting verb to format successive arguments passed in the call.
@@ -211,7 +211,7 @@
 		fmt.Sprintf("%d %d %#[1]x %#x", 16, 17)
 	will yield "16 17 0x10 0x11".
 
-	Format errors:
+	Format errors
 
 	If an invalid argument is given for a verb, such as providing
 	a string to %d, the generated string will contain a

src/go/internal/gcimporter/gcimporter.go

@@ -145,17 +145,14 @@ func Import(fset *token.FileSet, packages map[string]*types.Package, path, srcDi
 		err = fmt.Errorf("import %q: old textual export format no longer supported (recompile library)", path)
 
 	case "$$B\n":
-		var data []byte
-		data, err = io.ReadAll(buf)
-		if err != nil {
-			break
-		}
+		var exportFormat byte
+		exportFormat, err = buf.ReadByte()
 
 		// The indexed export format starts with an 'i'; the older
 		// binary export format starts with a 'c', 'd', or 'v'
 		// (from "version"). Select appropriate importer.
-		if len(data) > 0 && data[0] == 'i' {
-			_, pkg, err = iImportData(fset, packages, data[1:], id)
+		if err == nil && exportFormat == 'i' {
+			pkg, err = iImportData(fset, packages, buf, id)
 		} else {
 			err = fmt.Errorf("import %q: old binary export format no longer supported (recompile library)", path)
 		}

src/go/internal/gcimporter/iimport.go

@@ -8,6 +8,7 @@
 package gcimporter
 
 import (
+	"bufio"
 	"bytes"
 	"encoding/binary"
 	"fmt"
@@ -20,7 +21,7 @@ import (
 )
 
 type intReader struct {
-	*bytes.Reader
+	*bufio.Reader
 	path string
 }
 
@@ -61,7 +62,7 @@ const (
 // and returns the number of bytes consumed and a reference to the package.
 // If the export data version is not recognized or the format is otherwise
 // compromised, an error is returned.
-func iImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
+func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataReader *bufio.Reader, path string) (pkg *types.Package, err error) {
 	const currentVersion = 1
 	version := int64(-1)
 	defer func() {
@@ -74,7 +75,7 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 		}
 	}()
 
-	r := &intReader{bytes.NewReader(data), path}
+	r := &intReader{dataReader, path}
 
 	version = int64(r.uint64())
 	switch version {
@@ -86,10 +87,12 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 	sLen := int64(r.uint64())
 	dLen := int64(r.uint64())
 
-	whence, _ := r.Seek(0, io.SeekCurrent)
-	stringData := data[whence : whence+sLen]
-	declData := data[whence+sLen : whence+sLen+dLen]
-	r.Seek(sLen+dLen, io.SeekCurrent)
+	data := make([]byte, sLen+dLen)
+	if _, err := io.ReadFull(r, data); err != nil {
+		errorf("cannot read %d bytes of stringData and declData: %s", len(data), err)
+	}
+	stringData := data[:sLen]
+	declData := data[sLen:]
 
 	p := iimporter{
 		ipath:   path,
@@ -165,9 +168,7 @@ func iImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 
 	// package was imported completely and without errors
 	localpkg.MarkComplete()
-
-	consumed, _ := r.Seek(0, io.SeekCurrent)
-	return int(consumed), localpkg, nil
+	return localpkg, nil
 }
 
 type iimporter struct {

src/net/http/server.go

@@ -577,37 +577,17 @@ func (w *response) ReadFrom(src io.Reader) (n int64, err error) {
 		return io.CopyBuffer(writerOnly{w}, src, buf)
 	}
 
-	// sendfile path:
-
-	// Do not start actually writing response until src is readable.
-	// If body length is <= sniffLen, sendfile/splice path will do
-	// little anyway. This small read also satisfies sniffing the
-	// body in case Content-Type is missing.
-	nr, er := src.Read(buf[:sniffLen])
-	atEOF := errors.Is(er, io.EOF)
-	n += int64(nr)
-
-	if nr > 0 {
-		// Write the small amount read normally.
-		nw, ew := w.Write(buf[:nr])
-		if ew != nil {
-			err = ew
-		} else if nr != nw {
-			err = io.ErrShortWrite
+	// Copy the first sniffLen bytes before switching to ReadFrom.
+	// This ensures we don't start writing the response before the
+	// source is available (see golang.org/issue/5660) and provides
+	// enough bytes to perform Content-Type sniffing when required.
+	if !w.cw.wroteHeader {
+		n0, err := io.CopyBuffer(writerOnly{w}, io.LimitReader(src, sniffLen), buf)
+		n += n0
+		if err != nil || n0 < sniffLen {
+			return n, err
 		}
 	}
-	if err == nil && er != nil && !atEOF {
-		err = er
-	}
-
-	// Do not send StatusOK in the error case where nothing has been written.
-	if err == nil && !w.wroteHeader {
-		w.WriteHeader(StatusOK) // nr == 0, no error (or EOF)
-	}
-
-	if err != nil || atEOF {
-		return n, err
-	}
 
 	w.w.Flush()  // get rid of any previous writes
 	w.cw.flush() // make sure Header is written; flush data to rwc
@@ -620,7 +600,7 @@ func (w *response) ReadFrom(src io.Reader) (n int64, err error) {
 		return n, err
 	}
 
-	n0, err := io.Copy(writerOnly{w}, src)
+	n0, err := io.CopyBuffer(writerOnly{w}, src, buf)
 	n += n0
 	return n, err
 }