mirror of
https://github.com/golang/go
synced 2024-09-04 23:44:16 +00:00
cmd/internal/gc, cmd/yacc: restore custom syntax error messages
This restores go.errors from before3af0d79
along with a fixed up version of the bisonerrors AWK script, translated to Go. However, this means Yyerror needs access to the yacc parser's state, which is currently private. To workaround that, add a "state" accessor method like the Lookahead method added inc7fa3c6
. Update issue #9968. Change-Id: Ib868789e92fdb7d135442120a392457923e50121 Reviewed-on: https://go-review.googlesource.com/7270 Reviewed-by: Russ Cox <rsc@golang.org> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
parent
e5a0d6399e
commit
398bf9d5a0
81
src/cmd/internal/gc/go.errors
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81
src/cmd/internal/gc/go.errors
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@ -0,0 +1,81 @@
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Example-based syntax error messages.
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// See yaccerrors.go.
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package gc
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var yymsg = []struct {
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yystate int
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yychar int
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msg string
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}{
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// Each line of the form % token list
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// is converted by yaccerrors.go into the yystate and yychar caused
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// by that token list.
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% loadsys package LIMPORT '(' LLITERAL import_package import_there ','
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"unexpected comma during import block"},
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% loadsys package LIMPORT LNAME ';'
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"missing import path; require quoted string"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LIF if_header ';'
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"missing { after if clause"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LSWITCH if_header ';'
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"missing { after switch clause"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LFOR for_header ';'
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"missing { after for clause"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LFOR ';' LBODY
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"missing { after for clause"},
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% loadsys package imports LFUNC LNAME '(' ')' ';' '{'
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"unexpected semicolon or newline before {"},
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% loadsys package imports LTYPE LNAME ';'
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"unexpected semicolon or newline in type declaration"},
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% loadsys package imports LCHAN '}'
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"unexpected } in channel type"},
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% loadsys package imports LCHAN ')'
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"unexpected ) in channel type"},
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% loadsys package imports LCHAN ','
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"unexpected comma in channel type"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' if_stmt ';' LELSE
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"unexpected semicolon or newline before else"},
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% loadsys package imports LTYPE LNAME LINTERFACE '{' LNAME ',' LNAME
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"name list not allowed in interface type"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LFOR LVAR LNAME '=' LNAME
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"var declaration not allowed in for initializer"},
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% loadsys package imports LVAR LNAME '[' ']' LNAME '{'
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"unexpected { at end of statement"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LVAR LNAME '[' ']' LNAME '{'
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"unexpected { at end of statement"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LDEFER LNAME ';'
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"argument to go/defer must be function call"},
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% loadsys package imports LVAR LNAME '=' LNAME '{' LNAME ';'
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"need trailing comma before newline in composite literal"},
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% loadsys package imports LVAR LNAME '=' comptype '{' LNAME ';'
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"need trailing comma before newline in composite literal"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LFUNC LNAME
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"nested func not allowed"},
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% loadsys package imports LFUNC LNAME '(' ')' '{' LIF if_header loop_body LELSE ';'
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"else must be followed by if or statement block"},
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}
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@ -3,6 +3,7 @@
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// license that can be found in the LICENSE file.
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//go:generate go tool yacc go.y
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//go:generate go run yaccerrors.go
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//go:generate go run mkbuiltin.go runtime unsafe
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package gc
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@ -1782,11 +1783,6 @@ func pragcgo(text string) {
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type yy struct{}
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var yymsg []struct {
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yystate, yychar int
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msg string
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}
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func (yy) Lex(v *yySymType) int {
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return int(yylex(v))
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}
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@ -122,10 +122,6 @@ func yyerrorl(line int, fmt_ string, args ...interface{}) {
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}
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}
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var yystate int
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var yychar_subr int
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var yyerror_lastsyntax int
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func Yyerror(fmt_ string, args ...interface{}) {
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@ -139,8 +135,11 @@ func Yyerror(fmt_ string, args ...interface{}) {
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if strings.HasPrefix(fmt_, "syntax error") {
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nsyntaxerrors++
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yystate := theparser.(*yyParserImpl).state()
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yychar := theparser.Lookahead()
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if Debug['x'] != 0 {
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fmt.Printf("yyerror: yystate=%d yychar=%d\n", yystate, yychar_subr)
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fmt.Printf("yyerror: yystate=%d yychar=%d\n", yystate, yychar)
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}
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// An unexpected EOF caused a syntax error. Use the previous
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@ -166,8 +165,8 @@ func Yyerror(fmt_ string, args ...interface{}) {
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}
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// look for parse state-specific errors in list (see go.errors).
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for i := 0; i < len(yymsg); i++ {
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if yymsg[i].yystate == yystate && yymsg[i].yychar == yychar_subr {
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for i := range yymsg {
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if yymsg[i].yystate == yystate && yymsg[i].yychar == yychar {
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yyerrorl(int(lexlineno), "syntax error: %s", yymsg[i].msg)
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return
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}
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@ -857,6 +857,7 @@ type yyParser interface {
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type yyParserImpl struct {
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lookahead func() int
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state func() int
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}
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func (p *yyParserImpl) Lookahead() int {
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@ -866,6 +867,7 @@ func (p *yyParserImpl) Lookahead() int {
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func yyNewParser() yyParser {
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p := &yyParserImpl{
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lookahead: func() int { return -1 },
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state: func() int { return -1 },
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}
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return p
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}
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@ -942,9 +944,11 @@ func (yyrcvr *yyParserImpl) Parse(yylex yyLexer) int {
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yystate := 0
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yychar := -1
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yytoken := -1 // yychar translated into internal numbering
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yyrcvr.state = func() int { return yystate }
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yyrcvr.lookahead = func() int { return yychar }
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defer func() {
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// Make sure we report no lookahead when not parsing.
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yystate = -1
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yychar = -1
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yytoken = -1
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}()
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194
src/cmd/internal/gc/yaccerrors.go
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194
src/cmd/internal/gc/yaccerrors.go
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ignore
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// This program implements the core idea from
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//
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// Clinton L. Jeffery, Generating LR syntax error messages from examples,
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// ACM TOPLAS 25(5) (September 2003). http://doi.acm.org/10.1145/937563.937566
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//
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// It reads Bison's summary of a grammar followed by a file
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// like go.errors, replacing lines beginning with % by the
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// yystate and yychar that will be active when an error happens
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// while parsing that line.
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//
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// Unlike the system described in the paper, the lines in go.errors
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// give grammar symbol name lists, not actual program fragments.
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// This is a little less programmer-friendly but doesn't require being
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// able to run the text through lex.c.
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package main
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import (
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"bufio"
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"fmt"
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"io"
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"log"
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"os"
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"strconv"
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"strings"
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)
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func xatoi(s string) int {
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n, err := strconv.Atoi(s)
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if err != nil {
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log.Fatal(err)
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}
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return n
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}
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func trimParen(s string) string {
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s = strings.TrimPrefix(s, "(")
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s = strings.TrimSuffix(s, ")")
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return s
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}
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type action struct {
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token string
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n int
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}
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var shift = map[int][]action{}
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var reduce = map[int][]action{}
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type rule struct {
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lhs string
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size int
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}
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var rules = map[int]rule{}
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func readYaccOutput() {
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r, err := os.Open("y.output")
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if err != nil {
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log.Fatal(err)
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}
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defer r.Close()
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var state int
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scanner := bufio.NewScanner(r)
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for scanner.Scan() {
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f := strings.Fields(scanner.Text())
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nf := len(f)
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if nf >= 4 && f[1] == "terminals," && f[3] == "nonterminals" {
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// We're done.
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break
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}
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if nf >= 2 && f[0] == "state" {
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state = xatoi(f[1])
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continue
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}
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if nf >= 3 && (f[1] == "shift" || f[1] == "goto") {
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shift[state] = append(shift[state], action{f[0], xatoi(f[2])})
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continue
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}
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if nf >= 3 && f[1] == "reduce" {
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reduce[state] = append(reduce[state], action{f[0], xatoi(f[2])})
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continue
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}
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if nf >= 3 && strings.HasSuffix(f[0], ":") && strings.HasPrefix(f[nf-1], "(") && strings.HasSuffix(f[nf-1], ")") {
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n := xatoi(trimParen(f[nf-1]))
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size := nf - 2
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if size == 1 && f[1] == "." {
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size = 0
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}
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rules[n] = rule{strings.TrimSuffix(f[0], ":"), size}
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continue
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}
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}
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}
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func runMachine(w io.Writer, s string) {
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f := strings.Fields(s)
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// Run it through the LR machine and print the induced "yystate, yychar,"
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// at the point where the error happens.
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var stack []int
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state := 0
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i := 1
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tok := ""
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Loop:
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if tok == "" && i < len(f) {
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tok = f[i]
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i++
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}
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for _, a := range shift[state] {
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if a.token == tok {
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if false {
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fmt.Println("SHIFT ", tok, " ", state, " -> ", a)
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}
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stack = append(stack, state)
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state = a.n
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tok = ""
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goto Loop
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}
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}
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for _, a := range reduce[state] {
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if a.token == tok || a.token == "." {
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stack = append(stack, state)
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rule, ok := rules[a.n]
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if !ok {
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log.Fatal("missing rule")
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}
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stack = stack[:len(stack)-rule.size]
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state = stack[len(stack)-1]
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stack = stack[:len(stack)-1]
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if tok != "" {
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i--
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}
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tok = rule.lhs
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if false {
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fmt.Println("REDUCE ", stack, " ", state, " ", tok, " rule ", rule)
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}
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goto Loop
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}
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}
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// No shift or reduce applied - found the error.
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fmt.Fprintf(w, "\t{%d, %s,\n", state, tok)
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}
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func processGoErrors() {
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r, err := os.Open("go.errors")
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if err != nil {
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log.Fatal(err)
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}
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defer r.Close()
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w, err := os.Create("yymsg.go")
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if err != nil {
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log.Fatal(err)
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}
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defer w.Close()
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fmt.Fprintf(w, "// DO NOT EDIT - generated with go generate\n\n")
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scanner := bufio.NewScanner(r)
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for scanner.Scan() {
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s := scanner.Text()
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// Treat % as first field on line as introducing a pattern (token sequence).
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if strings.HasPrefix(strings.TrimSpace(s), "%") {
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runMachine(w, s)
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continue
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}
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fmt.Fprintln(w, s)
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}
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}
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func main() {
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readYaccOutput()
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processGoErrors()
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}
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83
src/cmd/internal/gc/yymsg.go
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83
src/cmd/internal/gc/yymsg.go
Normal file
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@ -0,0 +1,83 @@
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// DO NOT EDIT - generated with go generate
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Example-based syntax error messages.
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// See yaccerrors.go.
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package gc
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var yymsg = []struct {
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yystate int
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yychar int
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msg string
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}{
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// Each line of the form % token list
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// is converted by bisonerrors into the yystate and yychar caused
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// by that token list.
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{332, ',',
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"unexpected comma during import block"},
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{89, ';',
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"missing import path; require quoted string"},
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{390, ';',
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"missing { after if clause"},
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{387, ';',
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"missing { after switch clause"},
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{279, ';',
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"missing { after for clause"},
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{498, LBODY,
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"missing { after for clause"},
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{17, '{',
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"unexpected semicolon or newline before {"},
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{111, ';',
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"unexpected semicolon or newline in type declaration"},
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{78, '}',
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"unexpected } in channel type"},
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{78, ')',
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"unexpected ) in channel type"},
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{78, ',',
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"unexpected comma in channel type"},
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{416, LELSE,
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"unexpected semicolon or newline before else"},
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{329, ',',
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"name list not allowed in interface type"},
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{279, LVAR,
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"var declaration not allowed in for initializer"},
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{25, '{',
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"unexpected { at end of statement"},
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{371, '{',
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"unexpected { at end of statement"},
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{122, ';',
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"argument to go/defer must be function call"},
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{398, ';',
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"need trailing comma before newline in composite literal"},
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{414, ';',
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"need trailing comma before newline in composite literal"},
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{124, LNAME,
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"nested func not allowed"},
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{650, ';',
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"else must be followed by if or statement block"},
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}
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@ -3212,6 +3212,7 @@ type $$Parser interface {
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type $$ParserImpl struct {
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lookahead func() int
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state func() int
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}
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func (p *$$ParserImpl) Lookahead() int {
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@ -3221,6 +3222,7 @@ func (p *$$ParserImpl) Lookahead() int {
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func $$NewParser() $$Parser {
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p := &$$ParserImpl{
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lookahead: func() int { return -1 },
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state: func() int { return -1 },
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}
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return p
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}
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|
@ -3297,9 +3299,11 @@ func ($$rcvr *$$ParserImpl) Parse($$lex $$Lexer) int {
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$$state := 0
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$$char := -1
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$$token := -1 // $$char translated into internal numbering
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$$rcvr.state = func() int { return $$state }
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$$rcvr.lookahead = func() int { return $$char }
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defer func() {
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// Make sure we report no lookahead when not parsing.
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$$state = -1
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$$char = -1
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$$token = -1
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}()
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@ -1,6 +1,3 @@
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// skip
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// TODO(rsc): Reenable. See issue 9968.
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// errorcheck
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// Copyright 2009 The Go Authors. All rights reserved.
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|
@ -18,4 +15,3 @@ type I interface {
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type J interface {
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h T; // ERROR "syntax|signature"
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}
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@ -1,6 +1,3 @@
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// skip
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// TODO(rsc): Reenable. See issue 9968.
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// errorcheck
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|
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// Copyright 2012 The Go Authors. All rights reserved.
|
||||
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