* src/lread.c (read1): Phase out old-style backquotes a bit more.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/lread.c b/src/lread.c
index 3a77a62b27f..c73f7f32e51 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2683,7 +2683,17 @@ read1 (readcharfun, pch, first_in_list)
       }
 
     case '`':
-      if (first_in_list)
+      /* Transition from old-style to new-style:
+         If we see "(`" it used to mean old-style, which usually works
+         fine because ` should almost never appear in such a position
+         for new-style.  But occasionally we need "(`" to mean new
+         style, so we try to distinguish the two by the fact that we
+         can either write "( `foo" or "(` foo", where the first
+         intends to use new-style whereas the second intends to use
+         old-style.  For Emacs-25, we should completely remove this
+         first_in_list exception (old-style can still be obtained via
+         "(\`" anyway).  */
+      if (first_in_list && (c = READCHAR, UNREAD (c), c == ' '))
         {
           Vold_style_backquotes = Qt;
           goto default_label;