all: remove a few unused parameters

I recently modified tabwriter to reduce the number of defers due to
flush calls. However, I forgot to notice that the new function
flushNoDefers can no longer return an error, due to the lack of the
defer.

In crypto/tls, hashForServerKeyExchange never returned a non-nil error,
so simplify the code.

Finally, in go/types and net we can find a few trivially unused
parameters, so remove them.

Change-Id: I54c8de83fbc944df432453b55c93008d7e810e61
Reviewed-on: https://go-review.googlesource.com/c/go/+/174131
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>

src/crypto/tls/key_agreement.go

@@ -106,19 +106,19 @@ func md5SHA1Hash(slices [][]byte) []byte {
 // hashForServerKeyExchange hashes the given slices and returns their digest
 // using the given hash function (for >= TLS 1.2) or using a default based on
 // the sigType (for earlier TLS versions).
-func hashForServerKeyExchange(sigType uint8, hashFunc crypto.Hash, version uint16, slices ...[]byte) ([]byte, error) {
+func hashForServerKeyExchange(sigType uint8, hashFunc crypto.Hash, version uint16, slices ...[]byte) []byte {
 	if version >= VersionTLS12 {
 		h := hashFunc.New()
 		for _, slice := range slices {
 			h.Write(slice)
 		}
 		digest := h.Sum(nil)
-		return digest, nil
+		return digest
 	}
 	if sigType == signatureECDSA {
-		return sha1Hash(slices), nil
+		return sha1Hash(slices)
 	}
-	return md5SHA1Hash(slices), nil
+	return md5SHA1Hash(slices)
 }
 
 // ecdheKeyAgreement implements a TLS key agreement where the server
@@ -185,10 +185,7 @@ NextCandidate:
 		return nil, errors.New("tls: certificate cannot be used with the selected cipher suite")
 	}
 
-	digest, err := hashForServerKeyExchange(sigType, hashFunc, ka.version, clientHello.random, hello.random, serverECDHParams)
-	if err != nil {
-		return nil, err
-	}
+	digest := hashForServerKeyExchange(sigType, hashFunc, ka.version, clientHello.random, hello.random, serverECDHParams)
 
 	signOpts := crypto.SignerOpts(hashFunc)
 	if sigType == signatureRSAPSS {
@@ -297,10 +294,7 @@ func (ka *ecdheKeyAgreement) processServerKeyExchange(config *Config, clientHell
 	}
 	sig = sig[2:]
 
-	digest, err := hashForServerKeyExchange(sigType, hashFunc, ka.version, clientHello.random, serverHello.random, serverECDHParams)
-	if err != nil {
-		return err
-	}
+	digest := hashForServerKeyExchange(sigType, hashFunc, ka.version, clientHello.random, serverHello.random, serverECDHParams)
 	return verifyHandshakeSignature(sigType, cert.PublicKey, hashFunc, digest, sig)
 }
 

src/go/types/call.go

@@ -241,7 +241,7 @@ func (check *Checker) arguments(x *operand, call *ast.CallExpr, sig *Signature,
 			if i == n-1 && call.Ellipsis.IsValid() {
 				ellipsis = call.Ellipsis
 			}
-			check.argument(call.Fun, sig, i, x, ellipsis, context)
+			check.argument(sig, i, x, ellipsis, context)
 		}
 	}
 
@@ -259,7 +259,7 @@ func (check *Checker) arguments(x *operand, call *ast.CallExpr, sig *Signature,
 
 // argument checks passing of argument x to the i'th parameter of the given signature.
 // If ellipsis is valid, the argument is followed by ... at that position in the call.
-func (check *Checker) argument(fun ast.Expr, sig *Signature, i int, x *operand, ellipsis token.Pos, context string) {
+func (check *Checker) argument(sig *Signature, i int, x *operand, ellipsis token.Pos, context string) {
 	check.singleValue(x)
 	if x.mode == invalid {
 		return

src/net/dnsclient_unix.go

@@ -183,7 +183,7 @@ func (r *Resolver) exchange(ctx context.Context, server string, q dnsmessage.Que
 }
 
 // checkHeader performs basic sanity checks on the header.
-func checkHeader(p *dnsmessage.Parser, h dnsmessage.Header, name, server string) error {
+func checkHeader(p *dnsmessage.Parser, h dnsmessage.Header) error {
 	if h.RCode == dnsmessage.RCodeNameError {
 		return errNoSuchHost
 	}
@@ -214,7 +214,7 @@ func checkHeader(p *dnsmessage.Parser, h dnsmessage.Header, name, server string)
 	return nil
 }
 
-func skipToAnswer(p *dnsmessage.Parser, qtype dnsmessage.Type, name, server string) error {
+func skipToAnswer(p *dnsmessage.Parser, qtype dnsmessage.Type) error {
 	for {
 		h, err := p.AnswerHeader()
 		if err == dnsmessage.ErrSectionDone {
@@ -272,7 +272,7 @@ func (r *Resolver) tryOneName(ctx context.Context, cfg *dnsConfig, name string,
 				continue
 			}
 
-			if err := checkHeader(&p, h, name, server); err != nil {
+			if err := checkHeader(&p, h); err != nil {
 				dnsErr := &DNSError{
 					Err:    err.Error(),
 					Name:   name,
@@ -292,7 +292,7 @@ func (r *Resolver) tryOneName(ctx context.Context, cfg *dnsConfig, name string,
 				continue
 			}
 
-			err = skipToAnswer(&p, qtype, name, server)
+			err = skipToAnswer(&p, qtype)
 			if err == nil {
 				return p, server, nil
 			}

src/text/tabwriter/tabwriter.go

@@ -499,13 +499,14 @@ func (b *Writer) Flush() error {
 // don't want to expose.
 func (b *Writer) flush() (err error) {
 	defer b.handlePanic(&err, "Flush")
-	return b.flushNoDefers()
+	b.flushNoDefers()
+	return nil
 }
 
 // flushNoDefers is like flush, but without a deferred handlePanic call. This
 // can be called from other methods which already have their own deferred
 // handlePanic calls, such as Write, and avoid the extra defer work.
-func (b *Writer) flushNoDefers() (err error) {
+func (b *Writer) flushNoDefers() {
 	// add current cell if not empty
 	if b.cell.size > 0 {
 		if b.endChar != 0 {
@@ -518,7 +519,6 @@ func (b *Writer) flushNoDefers() (err error) {
 	// format contents of buffer
 	b.format(0, 0, len(b.lines))
 	b.reset()
-	return nil
 }
 
 var hbar = []byte("---\n")
@@ -551,9 +551,7 @@ func (b *Writer) Write(buf []byte) (n int, err error) {
 						// the formatting of the following lines (the last cell per
 						// line is ignored by format()), thus we can flush the
 						// Writer contents.
-						if err = b.flushNoDefers(); err != nil {
-							return
-						}
+						b.flushNoDefers()
 						if ch == '\f' && b.flags&Debug != 0 {
 							// indicate section break
 							b.write0(hbar)