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.

1 files changed, 8 insertions, 11 deletions

diff --git a/src/lisp.h b/src/lisp.h
index aefdaeaf12f..f0c0c5a14a5 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2679,18 +2679,15 @@ struct Lisp_Buffer_Objfwd
    in the buffer structure itself.  They are handled differently,
    using struct Lisp_Buffer_Objfwd.)
 
-   The `realvalue' slot holds the variable's current value, or a
-   forwarding pointer to where that value is kept.  This value is the
-   one that corresponds to the loaded binding.  To read or set the
-   variable, you must first make sure the right binding is loaded;
-   then you can access the value in (or through) `realvalue'.
-
-   `where' is the buffer for which the loaded binding was found.  If
-   it has changed, to make sure the right binding is loaded it is
+   The `valcell' slot holds the variable's current value (unless `fwd'
+   is set).  This value is the one that corresponds to the loaded binding.
+   To read or set the variable, you must first make sure the right binding
+   is loaded; then you can access the value in (or through) `valcell'.
+
+   `where' is the buffer for which the loaded binding was found.
+   If it has changed, to make sure the right binding is loaded it is
    necessary to find which binding goes with the current buffer, then
-   load it.  To load it, first unload the previous binding, then copy
-   the value of the new binding into `realvalue' (or through it).
-   Also update LOADED-BINDING to point to the newly loaded binding.
+   load it.  To load it, first unload the previous binding.
 
    `local_if_set' indicates that merely setting the variable creates a
    local binding for the current buffer.  Otherwise the latter, setting