cmd/compile: remove old lexer and parser

Change-Id: I7306d28930dc4538a3bee31ff5d22f3f40681ec5
Reviewed-on: https://go-review.googlesource.com/32020
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -487,23 +487,6 @@ func colasdefn(left []*Node, defn *Node) {
 	}
 }
 
-func colas(left, right []*Node, lno int32) *Node {
-	n := nod(OAS, nil, nil) // assume common case
-	n.Colas = true
-	n.Lineno = lno     // set before calling colasdefn for correct error line
-	colasdefn(left, n) // modifies left, call before using left[0] in common case
-	if len(left) == 1 && len(right) == 1 {
-		// common case
-		n.Left = left[0]
-		n.Right = right[0]
-	} else {
-		n.Op = OAS2
-		n.List.Set(left)
-		n.Rlist.Set(right)
-	}
-	return n
-}
-
 // declare the arguments in an
 // interface field declaration.
 func ifacedcl(n *Node) {

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

@@ -27,8 +27,6 @@ var imported_unsafe bool
 
 var (
 	buildid string
-
-	flag_newparser bool
 )
 
 var (
@@ -181,7 +179,6 @@ func Main() {
 	obj.Flagcount("live", "debug liveness analysis", &debuglive)
 	obj.Flagcount("m", "print optimization decisions", &Debug['m'])
 	flag.BoolVar(&flag_msan, "msan", false, "build code compatible with C/C++ memory sanitizer")
-	flag.BoolVar(&flag_newparser, "newparser", true, "use new parser")
 	flag.BoolVar(&nolocalimports, "nolocalimports", false, "reject local (relative) imports")
 	flag.StringVar(&outfile, "o", "", "write output to `file`")
 	flag.StringVar(&myimportpath, "p", "", "set expected package import `path`")
@@ -320,11 +317,7 @@ func Main() {
 		block = 1
 		iota_ = -1000000
 		imported_unsafe = false
-		if flag_newparser {
-			parseFile(infile)
-		} else {
-			oldParseFile(infile)
-		}
+		parseFile(infile)
 		if nsyntaxerrors != 0 {
 			errorexit()
 		}