1 files changed, 14 insertions, 9 deletions
diff --git a/libgo/go/text/scanner/scanner.go b/libgo/go/text/scanner/scanner.go
index 565650edf9c..e0d86e343da 100644
--- a/libgo/go/text/scanner/scanner.go
+++ b/libgo/go/text/scanner/scanner.go
@@ -5,7 +5,8 @@
 // Package scanner provides a scanner and tokenizer for UTF-8-encoded text.
 // It takes an io.Reader providing the source, which then can be tokenized
 // through repeated calls to the Scan function.  For compatibility with
-// existing tools, the NUL character is not allowed.
+// existing tools, the NUL character is not allowed. If the first character
+// in the source is a UTF-8 encoded byte order mark (BOM), it is discarded.
 //
 // By default, a Scanner skips white space and Go comments and recognizes all
 // literals as defined by the Go language specification.  It may be
@@ -208,11 +209,6 @@ func (s *Scanner) Init(src io.Reader) *Scanner {
 	return s
 }
 
-// TODO(gri): The code for next() and the internal scanner state could benefit
-//            from a rethink. While next() is optimized for the common ASCII
-//            case, the "corrections" needed for proper position tracking undo
-//            some of the attempts for fast-path optimization.
-
 // next reads and returns the next Unicode character. It is designed such
 // that only a minimal amount of work needs to be done in the common ASCII
 // case (one test to check for both ASCII and end-of-buffer, and one test
@@ -316,7 +312,11 @@ func (s *Scanner) Next() rune {
 // character of the source.
 func (s *Scanner) Peek() rune {
 	if s.ch < 0 {
+		// this code is only run for the very first character
 		s.ch = s.next()
+		if s.ch == '\uFEFF' {
+			s.ch = s.next() // ignore BOM
+		}
 	}
 	return s.ch
 }
@@ -389,15 +389,20 @@ func (s *Scanner) scanNumber(ch rune) (rune, rune) {
 		if ch == 'x' || ch == 'X' {
 			// hexadecimal int
 			ch = s.next()
+			hasMantissa := false
 			for digitVal(ch) < 16 {
 				ch = s.next()
+				hasMantissa = true
+			}
+			if !hasMantissa {
+				s.error("illegal hexadecimal number")
 			}
 		} else {
 			// octal int or float
-			seenDecimalDigit := false
+			has8or9 := false
 			for isDecimal(ch) {
 				if ch > '7' {
-					seenDecimalDigit = true
+					has8or9 = true
 				}
 				ch = s.next()
 			}
@@ -408,7 +413,7 @@ func (s *Scanner) scanNumber(ch rune) (rune, rune) {
 				return Float, ch
 			}
 			// octal int
-			if seenDecimalDigit {
+			if has8or9 {
 				s.error("illegal octal number")
 			}
 		}