Fix bug#30846, along with misc cleanups found along the way

* test/src/data-tests.el (data-tests-kill-all-local-variables): New test.

* src/buffer.c (swap_out_buffer_local_variables): Remove.
Fuse the body of its loop into that of reset_buffer_local_variables.
(Fkill_buffer, Fkill_all_local_variables): Don't call it any more.
(reset_buffer_local_variables): Make sure the buffer's local binding
is swapped out before removing it from the alist (bug#30846).
Call watchers before actually killing the var.

* src/data.c (Fmake_local_variable): Simplify.
Use swap_in_global_binding to swap out any local binding, instead of
a mix of find_symbol_value followed by messing with where&found.
Don't call swap_in_symval_forwarding since the currently swapped
binding is never one we've modified.
(Fkill_local_variable): Use swap_in_global_binding rather than messing
with where&found to try and trick find_symbol_value into doing the same.

* src/alloc.c (mark_localized_symbol): 'where' can't be a frame any more.

(cherry picked from commit 3ddff080341580eb6fc18d907181e9cc2301f62d)

1 files changed, 9 insertions, 27 deletions

diff --git a/src/data.c b/src/data.c
index 45b2bf73026..4bee194e296 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1188,7 +1188,7 @@ swap_in_global_binding (struct Lisp_Symbol *symbol)
 
   /* Indicate that the global binding is set up now.  */
   set_blv_where (blv, Qnil);
-  set_blv_found (blv, 0);
+  set_blv_found (blv, false);
 }
 
 /* Set up the buffer-local symbol SYMBOL for validity in the current buffer.
@@ -1257,7 +1257,6 @@ find_symbol_value (Lisp_Object symbol)
         swap_in_symval_forwarding (sym, blv);
         return blv->fwd ? do_symval_forwarding (blv->fwd) : blv_value (blv);
       }
-      /* FALLTHROUGH */
     case SYMBOL_FORWARDED:
       return do_symval_forwarding (SYMBOL_FWD (sym));
     default: emacs_abort ();
@@ -1366,7 +1365,7 @@ set_internal (Lisp_Object symbol, Lisp_Object newval, Lisp_Object where,
             tem1 = assq_no_quit (symbol,
                                  BVAR (XBUFFER (where), local_var_alist));
             set_blv_where (blv, where);
-            blv->found = 1;
+            blv->found = true;
 
             if (NILP (tem1))
               {
@@ -1381,7 +1380,7 @@ set_internal (Lisp_Object symbol, Lisp_Object newval, Lisp_Object where,
                 if (bindflag || !blv->local_if_set
                     || let_shadows_buffer_binding_p (sym))
                   {
-                    blv->found = 0;
+                    blv->found = false;
                     tem1 = blv->defcell;
                   }
                 /* If it's a local_if_set, being set not bound,
@@ -1796,7 +1795,7 @@ make_blv (struct Lisp_Symbol *sym, bool forwarded,
   blv->local_if_set = 0;
   set_blv_defcell (blv, tem);
   set_blv_valcell (blv, tem);
-  set_blv_found (blv, 0);
+  set_blv_found (blv, false);
   return blv;
 }
 
@@ -1946,30 +1945,17 @@ Instead, use `add-hook' and specify t for the LOCAL argument.  */)
           CALLN (Fmessage, format, SYMBOL_NAME (variable));
         }
 
-      /* Swap out any local binding for some other buffer, and make
-         sure the current value is permanently recorded, if it's the
-         default value.  */
-      find_symbol_value (variable);
+      if (BUFFERP (blv->where) && current_buffer == XBUFFER (blv->where))
+        /* Make sure the current value is permanently recorded, if it's the
+           default value.  */
+        swap_in_global_binding (sym);
 
       bset_local_var_alist
         (current_buffer,
          Fcons (Fcons (variable, XCDR (blv->defcell)),
                 BVAR (current_buffer, local_var_alist)));
-
-      /* Make sure symbol does not think it is set up for this buffer;
-         force it to look once again for this buffer's value.  */
-      if (current_buffer == XBUFFER (blv->where))
-        set_blv_where (blv, Qnil);
-      set_blv_found (blv, 0);
     }
 
-  /* If the symbol forwards into a C variable, then load the binding
-     for this buffer now.  If C code modifies the variable before we
-     load the binding in, then that new value will clobber the default
-     binding the next time we unload it.  */
-  if (blv->fwd)
-    swap_in_symval_forwarding (sym, blv);
-
   return variable;
 }
 
@@ -2031,11 +2017,7 @@ From now on the default value will apply in this buffer.  Return VARIABLE.  */)
   {
     Lisp_Object buf; XSETBUFFER (buf, current_buffer);
     if (EQ (buf, blv->where))
-      {
-        set_blv_where (blv, Qnil);
-        blv->found = 0;
-        find_symbol_value (variable);
-      }
+      swap_in_global_binding (sym);
   }
 
   return variable;