(specbind): If binding a per-buffer variable which

doesn't have a buffer-local value in the current buffer, change
the global value by changing the value of the symbol bound in all
buffers not having their own value, to make it consistent with
what happens with other buffer-local variables.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/eval.c b/src/eval.c
index 8d8b9b14d42..41085cdef5c 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2899,16 +2899,31 @@ specbind (symbol, value)
           || BUFFER_OBJFWDP (XSYMBOL (symbol)->value))
         {
           Lisp_Object current_buffer, binding_buffer;
+          
           /* For a local variable, record both the symbol and which
              buffer's value we are saving.  */
           current_buffer = Fcurrent_buffer ();
           binding_buffer = current_buffer;
+          
           /* If the variable is not local in this buffer,
              we are saving the global value, so restore that.  */
           if (NILP (Flocal_variable_p (symbol, binding_buffer)))
             binding_buffer = Qnil;
           specpdl_ptr->symbol
             = Fcons (symbol, Fcons (binding_buffer, current_buffer));
+
+          /* If SYMBOL is a per-buffer variable which doesn't have a
+             buffer-local value here, make the `let' change the global
+             value by changing the value of SYMBOL in all buffers not
+             having their own value.  This is consistent with what
+             happens with other buffer-local variables.  */
+          if (NILP (binding_buffer)
+              && BUFFER_OBJFWDP (XSYMBOL (symbol)->value))
+            {
+              ++specpdl_ptr;
+              Fset_default (symbol, value);
+              return;
+            }
         }
       else
         specpdl_ptr->symbol = symbol;