interpreter: correct semantics of special var args.

In this patch we eliminate the special operator
sys:with-dyn-rebinds, and implement correct semantics for
dynamically scoped variables that occur in argument
lists.

* eval.c (with_dyn_rebinds_s): Symbol variable removed.
(bind_args): Handle special variables dynamically:
for each symbol that appears, check whether it is a special
and treat accordingly by allocating a new dynamic environment
if necessary, and binding in that environment.
This adds overhead, which is why I moved away from this
approach in the past. But now that there is a compiler,
overhead in the interpreter matters less. Correct semantics
is more important.
(expand_params): Greatly simplified for not having to wrap the
sys:with-dyn-rebinds operator around the body.
(funcall_interp): Since bind_args can now extend the dynamic
environment, it is necessary to save and restore dyn_env
around it. Another call to bind_args occurs in op_catch;
that already saves and restores dyn_env.
(op_with_dyn_rebinds): Static function removed.
(do_expand): with-dyn-rebinds-s case removed.
(eval_init): Removed interning of sys:with-dyn-rebinds
symbol and registration of special op.

* protsym.c: Regenerated.

* compiler.tl (compiler compile): Remove case which handles
sys:with-dyn-rebinds.

1 files changed, 6 insertions, 6 deletions

diff --git a/protsym.c b/protsym.c
index 5c0db635..87e2ff42 100644
--- a/protsym.c
+++ b/protsym.c
@@ -128,9 +128,9 @@ extern val ushort_s, uw_protect_s, val_s, var_k, var_s;
 extern val vars_k, vec_list_s, vec_s, vecref_s, vector_lit_s;
 extern val vm_closure_s, vm_desc_s, void_s, warning_s, wchar_s;
 extern val weak_keys_k, weak_vals_k, when_s, while_s, while_star_s;
-extern val whole_k, wild_s, with_dyn_rebinds_s, word_char_k, wrap_k;
-extern val wstr_d_s, wstr_s, year_s, zap_s, zarray_s;
-extern val zeroplus_s, zone_s;
+extern val whole_k, wild_s, word_char_k, wrap_k, wstr_d_s;
+extern val wstr_s, year_s, zap_s, zarray_s, zeroplus_s;
+extern val zone_s;
 
 #if CONFIG_DEBUG_SUPPORT
 extern val debug_quit_s;
@@ -259,9 +259,9 @@ val *protected_sym[] = {
   &vars_k, &vec_list_s, &vec_s, &vecref_s, &vector_lit_s,
   &vm_closure_s, &vm_desc_s, &void_s, &warning_s, &wchar_s,
   &weak_keys_k, &weak_vals_k, &when_s, &while_s, &while_star_s,
-  &whole_k, &wild_s, &with_dyn_rebinds_s, &word_char_k, &wrap_k,
-  &wstr_d_s, &wstr_s, &year_s, &zap_s, &zarray_s,
-  &zeroplus_s, &zone_s,
+  &whole_k, &wild_s, &word_char_k, &wrap_k, &wstr_d_s,
+  &wstr_s, &year_s, &zap_s, &zarray_s, &zeroplus_s,
+  &zone_s,
 
 #if CONFIG_DEBUG_SUPPORT
   &debug_quit_s,