go/scanner: line comments may end in EOF

R=rsc
CC=golang-dev
https://golang.org/cl/2908041

src/pkg/go/scanner/scanner.go

@@ -183,29 +183,25 @@ func (S *Scanner) scanComment() {
 
 	if S.ch == '/' {
 		//-style comment
-		for S.ch >= 0 {
+		S.next()
+		for S.ch != '\n' && S.ch >= 0 {
 			S.next()
-			if S.ch == '\n' {
-				// '\n' is not part of the comment for purposes of scanning
-				// (the comment ends on the same line where it started)
-				if col == 1 {
-					// comment starts at the beginning of the current line
-					S.interpretLineComment(S.src[offs:S.offset])
-				}
-				return
-			}
 		}
+		if col == 1 {
+			// comment starts at the beginning of the current line
+			S.interpretLineComment(S.src[offs:S.offset])
+		}
+		return
+	}
 
-	} else {
-		/*-style comment */
+	/*-style comment */
+	S.next()
+	for S.ch >= 0 {
+		ch := S.ch
 		S.next()
-		for S.ch >= 0 {
-			ch := S.ch
+		if ch == '*' && S.ch == '/' {
 			S.next()
-			if ch == '*' && S.ch == '/' {
-				S.next()
-				return
-			}
+			return
 		}
 	}
 

src/pkg/go/scanner/scanner_test.go

@@ -395,12 +395,14 @@ var lines = []string{
 	"var\n",
 
 	"foo$//comment\n",
+	"foo$//comment",
 	"foo$/*comment*/\n",
 	"foo$/*\n*/",
 	"foo$/*comment*/    \n",
 	"foo$/*\n*/    ",
 
 	"foo    $// comment\n",
+	"foo    $// comment",
 	"foo    $/*comment*/\n",
 	"foo    $/*\n*/",
 	"foo    $/*  */ /* \n */ bar$/**/\n",
@@ -410,7 +412,8 @@ var lines = []string{
 	"foo    $/*0*/ /*1*/ /*2*/    \n",
 	"foo	$/**/ /*-------------*/       /*----\n*/bar       $/*  \n*/baa$\n",
 	"foo    $/* an EOF terminates a line */",
-	"foo    $/* an EOF terminates a line *//*",
+	"foo    $/* an EOF terminates a line */ /*",
+	"foo    $/* an EOF terminates a line */ //",
 
 	"package main$\n\nfunc main() {\n\tif {\n\t\treturn /* */ }$\n}$\n",
 	"package main$",
@@ -626,8 +629,6 @@ var errors = []struct {
 	{"`", token.STRING, 0, "string not terminated"},
 	{"/**/", token.COMMENT, 0, ""},
 	{"/*", token.COMMENT, 0, "comment not terminated"},
-	{"//\n", token.COMMENT, 0, ""},
-	{"//", token.COMMENT, 0, "comment not terminated"},
 	{"077", token.INT, 0, ""},
 	{"078.", token.FLOAT, 0, ""},
 	{"07801234567.", token.FLOAT, 0, ""},