(read1): Accept `single space' syntax like (? x).

1 files changed, 7 insertions, 0 deletions

diff --git a/src/lread.c b/src/lread.c
index 071bf679015..70f0a3f2f9b 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2258,6 +2258,13 @@ read1 (readcharfun, pch, first_in_list)
         if (c < 0)
           end_of_file_error ();
 
+        /* Accept `single space' syntax like (list ? x) where the
+           whitespace character is SPC or TAB.
+           Other literal whitespace like NL, CR, and FF are not accepted,
+           as there are well-established escape sequences for these.  */
+        if (c == ' ' || c == '\t')
+          return make_number (c);
+
         if (c == '\\')
           c = read_escape (readcharfun, 0, &discard);
         else if (BASE_LEADING_CODE_P (c))