(Fformat): Detect invalid format letters for floats.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/editfns.c b/src/editfns.c
index 3b71d592bd1..51cf0c0b789 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -3259,7 +3259,12 @@ usage: (format STRING &rest OBJECTS)  */)
         else if (FLOATP (args[n]) && *format != 's')
           {
             if (! (*format == 'e' || *format == 'f' || *format == 'g'))
-              args[n] = Ftruncate (args[n], Qnil);
+              {
+                if (*format != 'd' && *format != 'o' && *format != 'x'
+                    && *format != 'i' && *format != 'X' && *format != 'c')
+                  error ("Invalid format operation %%%c", *format);
+                args[n] = Ftruncate (args[n], Qnil);
+              }
 
             /* Note that we're using sprintf to print floats,
                so we have to take into account what that function