coding.c: (Fdefine_coding_system_internal): Make an utf-8 base coding-system ASCII compatible only when it does not produce BOM on encoding (Bug#10383).

1 files changed, 2 insertions, 2 deletions

diff --git a/src/coding.c b/src/coding.c
index e15d725af3a..2db5385c932 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -9999,8 +9999,6 @@ usage: (define-coding-system-internal ...)  */)
     {
       Lisp_Object bom;
 
-      CODING_ATTR_ASCII_COMPAT (attrs) = Qt;
-
       if (nargs < coding_arg_utf8_max)
         goto short_args;
 
@@ -10014,6 +10012,8 @@ usage: (define-coding-system-internal ...)  */)
           CHECK_CODING_SYSTEM (val);
         }
       ASET (attrs, coding_attr_utf_bom, bom);
+      if (NILP (bom))
+        CODING_ATTR_ASCII_COMPAT (attrs) = Qt;
 
       category = (CONSP (bom) ? coding_category_utf_8_auto
                   : NILP (bom) ? coding_category_utf_8_nosig