src/pkg/[n-z]*: gofix -r error -force=error

R=golang-dev, bsiegert, iant
CC=golang-dev
https://golang.org/cl/5294074
diff --git a/src/pkg/regexp/all_test.go b/src/pkg/regexp/all_test.go
index 77f32ca..c707b11 100644
--- a/src/pkg/regexp/all_test.go
+++ b/src/pkg/regexp/all_test.go
@@ -5,7 +5,6 @@
 package regexp
 
 import (
-	"os"
 	"strings"
 	"testing"
 )
@@ -53,10 +52,10 @@
 }
 */
 
-func compileTest(t *testing.T, expr string, error os.Error) *Regexp {
+func compileTest(t *testing.T, expr string, error error) *Regexp {
 	re, err := Compile(expr)
 	if err != error {
-		t.Error("compiling `", expr, "`; unexpected error: ", err.String())
+		t.Error("compiling `", expr, "`; unexpected error: ", err.Error())
 	}
 	return re
 }
diff --git a/src/pkg/regexp/exec_test.go b/src/pkg/regexp/exec_test.go
index 905fd4e..499d1a5 100644
--- a/src/pkg/regexp/exec_test.go
+++ b/src/pkg/regexp/exec_test.go
@@ -104,7 +104,7 @@
 	for {
 		line, err := r.ReadString('\n')
 		if err != nil {
-			if err == os.EOF {
+			if err == io.EOF {
 				break
 			}
 			t.Fatalf("%s:%d: %v", file, lineno, err)
@@ -141,7 +141,7 @@
 			}
 			re, err = tryCompile(q)
 			if err != nil {
-				if err.String() == "error parsing regexp: invalid escape sequence: `\\C`" {
+				if err.Error() == "error parsing regexp: invalid escape sequence: `\\C`" {
 					// We don't and likely never will support \C; keep going.
 					continue
 				}
@@ -275,7 +275,7 @@
 	return true
 }
 
-func tryCompile(s string) (re *Regexp, err os.Error) {
+func tryCompile(s string) (re *Regexp, err error) {
 	// Protect against panic during Compile.
 	defer func() {
 		if r := recover(); r != nil {
@@ -370,7 +370,7 @@
 		lineno++
 		line, err := b.ReadString('\n')
 		if err != nil {
-			if err != os.EOF {
+			if err != io.EOF {
 				t.Errorf("%s:%d: %v", file, lineno, err)
 			}
 			break Reading
@@ -629,7 +629,7 @@
 			return
 		}
 		var v = -1
-		var err os.Error
+		var err error
 		if s[:i] != "?" {
 			v, err = strconv.Atoi(s[:i])
 			if err != nil {
diff --git a/src/pkg/regexp/regexp.go b/src/pkg/regexp/regexp.go
index a1b7951..9e9fb85 100644
--- a/src/pkg/regexp/regexp.go
+++ b/src/pkg/regexp/regexp.go
@@ -56,7 +56,6 @@
 import (
 	"bytes"
 	"io"
-	"os"
 	"regexp/syntax"
 	"strconv"
 	"strings"
@@ -69,7 +68,7 @@
 // Error is the local type for a parsing error.
 type Error string
 
-func (e Error) String() string {
+func (e Error) Error() string {
 	return string(e)
 }
 
@@ -108,7 +107,7 @@
 // that Perl, Python, and other implementations use, although this
 // package implements it without the expense of backtracking.
 // For POSIX leftmost-longest matching, see CompilePOSIX.
-func Compile(expr string) (*Regexp, os.Error) {
+func Compile(expr string) (*Regexp, error) {
 	return compile(expr, syntax.Perl, false)
 }
 
@@ -131,11 +130,11 @@
 // subexpression, then the second, and so on from left to right.
 // The POSIX rule is computationally prohibitive and not even well-defined.
 // See http://swtch.com/~rsc/regexp/regexp2.html#posix for details.
-func CompilePOSIX(expr string) (*Regexp, os.Error) {
+func CompilePOSIX(expr string) (*Regexp, error) {
 	return compile(expr, syntax.POSIX, true)
 }
 
-func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, os.Error) {
+func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
 	re, err := syntax.Parse(expr, mode)
 	if err != nil {
 		return nil, err
@@ -196,7 +195,7 @@
 func MustCompile(str string) *Regexp {
 	regexp, error := Compile(str)
 	if error != nil {
-		panic(`regexp: Compile(` + quote(str) + `): ` + error.String())
+		panic(`regexp: Compile(` + quote(str) + `): ` + error.Error())
 	}
 	return regexp
 }
@@ -207,7 +206,7 @@
 func MustCompilePOSIX(str string) *Regexp {
 	regexp, error := CompilePOSIX(str)
 	if error != nil {
-		panic(`regexp: CompilePOSIX(` + quote(str) + `): ` + error.String())
+		panic(`regexp: CompilePOSIX(` + quote(str) + `): ` + error.Error())
 	}
 	return regexp
 }
@@ -392,7 +391,7 @@
 // MatchReader checks whether a textual regular expression matches the text
 // read by the RuneReader.  More complicated queries need to use Compile and
 // the full Regexp interface.
-func MatchReader(pattern string, r io.RuneReader) (matched bool, error os.Error) {
+func MatchReader(pattern string, r io.RuneReader) (matched bool, error error) {
 	re, err := Compile(pattern)
 	if err != nil {
 		return false, err
@@ -403,7 +402,7 @@
 // MatchString checks whether a textual regular expression
 // matches a string.  More complicated queries need
 // to use Compile and the full Regexp interface.
-func MatchString(pattern string, s string) (matched bool, error os.Error) {
+func MatchString(pattern string, s string) (matched bool, error error) {
 	re, err := Compile(pattern)
 	if err != nil {
 		return false, err
@@ -414,7 +413,7 @@
 // Match checks whether a textual regular expression
 // matches a byte slice.  More complicated queries need
 // to use Compile and the full Regexp interface.
-func Match(pattern string, b []byte) (matched bool, error os.Error) {
+func Match(pattern string, b []byte) (matched bool, error error) {
 	re, err := Compile(pattern)
 	if err != nil {
 		return false, err
diff --git a/src/pkg/regexp/syntax/compile.go b/src/pkg/regexp/syntax/compile.go
index c90de3f..21c6565 100644
--- a/src/pkg/regexp/syntax/compile.go
+++ b/src/pkg/regexp/syntax/compile.go
@@ -1,9 +1,6 @@
 package syntax
 
-import (
-	"os"
-	"unicode"
-)
+import "unicode"
 
 // A patchList is a list of instruction pointers that need to be filled in (patched).
 // Because the pointers haven't been filled in yet, we can reuse their storage
@@ -76,7 +73,7 @@
 
 // Compile compiles the regexp into a program to be executed.
 // The regexp should have been simplified already (returned from re.Simplify).
-func Compile(re *Regexp) (*Prog, os.Error) {
+func Compile(re *Regexp) (*Prog, error) {
 	var c compiler
 	c.init()
 	f := c.compile(re)
diff --git a/src/pkg/regexp/syntax/parse.go b/src/pkg/regexp/syntax/parse.go
index f560262..29ad4d2 100644
--- a/src/pkg/regexp/syntax/parse.go
+++ b/src/pkg/regexp/syntax/parse.go
@@ -5,7 +5,6 @@
 package syntax
 
 import (
-	"os"
 	"sort"
 	"strings"
 	"unicode"
@@ -19,7 +18,7 @@
 	Expr string
 }
 
-func (e *Error) String() string {
+func (e *Error) Error() string {
 	return "error parsing regexp: " + e.Code.String() + ": `" + e.Expr + "`"
 }
 
@@ -222,7 +221,7 @@
 // before is the regexp suffix starting at the repetition operator.
 // after is the regexp suffix following after the repetition operator.
 // repeat returns an updated 'after' and an error, if any.
-func (p *parser) repeat(op Op, min, max int, before, after, lastRepeat string) (string, os.Error) {
+func (p *parser) repeat(op Op, min, max int, before, after, lastRepeat string) (string, error) {
 	flags := p.flags
 	if p.flags&PerlX != 0 {
 		if len(after) > 0 && after[0] == '?' {
@@ -649,7 +648,7 @@
 
 // Parsing.
 
-func Parse(s string, flags Flags) (*Regexp, os.Error) {
+func Parse(s string, flags Flags) (*Regexp, error) {
 	if flags&Literal != 0 {
 		// Trivial parser for literal string.
 		if err := checkUTF8(s); err != nil {
@@ -661,7 +660,7 @@
 	// Otherwise, must do real work.
 	var (
 		p          parser
-		err        os.Error
+		err        error
 		c          rune
 		op         Op
 		lastRepeat string
@@ -889,7 +888,7 @@
 // parsePerlFlags parses a Perl flag setting or non-capturing group or both,
 // like (?i) or (?: or (?i:.  It removes the prefix from s and updates the parse state.
 // The caller must have ensured that s begins with "(?".
-func (p *parser) parsePerlFlags(s string) (rest string, err os.Error) {
+func (p *parser) parsePerlFlags(s string) (rest string, err error) {
 	t := s
 
 	// Check for named captures, first introduced in Python's regexp library.
@@ -1069,7 +1068,7 @@
 }
 
 // parseVerticalBar handles a | in the input.
-func (p *parser) parseVerticalBar() os.Error {
+func (p *parser) parseVerticalBar() error {
 	p.concat()
 
 	// The concatenation we just parsed is on top of the stack.
@@ -1152,7 +1151,7 @@
 }
 
 // parseRightParen handles a ) in the input.
-func (p *parser) parseRightParen() os.Error {
+func (p *parser) parseRightParen() error {
 	p.concat()
 	if p.swapVerticalBar() {
 		// pop vertical bar
@@ -1186,7 +1185,7 @@
 
 // parseEscape parses an escape sequence at the beginning of s
 // and returns the rune.
-func (p *parser) parseEscape(s string) (r rune, rest string, err os.Error) {
+func (p *parser) parseEscape(s string) (r rune, rest string, err error) {
 	t := s[1:]
 	if t == "" {
 		return 0, "", &Error{ErrTrailingBackslash, ""}
@@ -1302,7 +1301,7 @@
 
 // parseClassChar parses a character class character at the beginning of s
 // and returns it.
-func (p *parser) parseClassChar(s, wholeClass string) (r rune, rest string, err os.Error) {
+func (p *parser) parseClassChar(s, wholeClass string) (r rune, rest string, err error) {
 	if s == "" {
 		return 0, "", &Error{Code: ErrMissingBracket, Expr: wholeClass}
 	}
@@ -1338,7 +1337,7 @@
 // parseNamedClass parses a leading POSIX named character class like [:alnum:]
 // from the beginning of s.  If one is present, it appends the characters to r
 // and returns the new slice r and the remainder of the string.
-func (p *parser) parseNamedClass(s string, r []rune) (out []rune, rest string, err os.Error) {
+func (p *parser) parseNamedClass(s string, r []rune) (out []rune, rest string, err error) {
 	if len(s) < 2 || s[0] != '[' || s[1] != ':' {
 		return
 	}
@@ -1401,7 +1400,7 @@
 // parseUnicodeClass parses a leading Unicode character class like \p{Han}
 // from the beginning of s.  If one is present, it appends the characters to r
 // and returns the new slice r and the remainder of the string.
-func (p *parser) parseUnicodeClass(s string, r []rune) (out []rune, rest string, err os.Error) {
+func (p *parser) parseUnicodeClass(s string, r []rune) (out []rune, rest string, err error) {
 	if p.flags&UnicodeGroups == 0 || len(s) < 2 || s[0] != '\\' || s[1] != 'p' && s[1] != 'P' {
 		return
 	}
@@ -1474,7 +1473,7 @@
 
 // parseClass parses a character class at the beginning of s
 // and pushes it onto the parse stack.
-func (p *parser) parseClass(s string) (rest string, err os.Error) {
+func (p *parser) parseClass(s string) (rest string, err error) {
 	t := s[1:] // chop [
 	re := p.newRegexp(OpCharClass)
 	re.Flags = p.flags
@@ -1824,7 +1823,7 @@
 	p[i], p[i+1], p[j], p[j+1] = p[j], p[j+1], p[i], p[i+1]
 }
 
-func checkUTF8(s string) os.Error {
+func checkUTF8(s string) error {
 	for s != "" {
 		rune, size := utf8.DecodeRuneInString(s)
 		if rune == utf8.RuneError && size == 1 {
@@ -1835,7 +1834,7 @@
 	return nil
 }
 
-func nextRune(s string) (c rune, t string, err os.Error) {
+func nextRune(s string) (c rune, t string, err error) {
 	c, size := utf8.DecodeRuneInString(s)
 	if c == utf8.RuneError && size == 1 {
 		return 0, "", &Error{Code: ErrInvalidUTF8, Expr: s}