Avoid undefined behavior in signed left shift.

[bpt/emacs.git] / src / regex.c

diff --git a/src/regex.c b/src/regex.c
index 2449240..622db70 100644 (file)
--- a/src/regex.c
+++ b/src/regex.c
@@ -713,7 +713,8 @@ typedef enum
 static int
 extract_number (re_char *source)
 {
-  return (SIGN_EXTEND_CHAR (source[1]) << 8) + source[0];
+  unsigned leading_byte = SIGN_EXTEND_CHAR (source[1]);
+  return (leading_byte << 8) + source[0];
 }
 
 /* Same as EXTRACT_NUMBER, except increment SOURCE to after the number.