Add `macroexp--dynamic-variable-p`

This predicate can be used for discriminating between lexically and
dynamically bound variables during macro-expansion (only).
It is restricted to internal use for the time being.

* lisp/emacs-lisp/bytecomp.el (byte-compile-initial-macro-environment):
Use macroexpand--all-toplevel.
* lisp/emacs-lisp/macroexp.el (macroexp-dynamic-variable-p): New.
(macroexp--expand-all): Maintain macroexp--dynvars.
(macroexpand-all): Rebind macroexp--dynvars.
(macroexpand--all-toplevel): New.
(internal-macroexpand-for-load): Use macroexpand--all-toplevel.
* src/eval.c (eval_sub): Transfer defvar declarations from
Vinternal_interpreter_environment into macroexp--dynvars during
lazy macro-expansion.
* src/lread.c (readevalloop): Rebind macroexp--dynvars around
read-and-evaluate operations.
(syms_of_lread): Define macroexp--dynvars.
* test/lisp/emacs-lisp/macroexp-resources/vk.el: New file.
* test/lisp/emacs-lisp/macroexp-tests.el (macroexp-tests--run-emacs)
(macroexp-tests--eval-in-subprocess)
(macroexp-tests--byte-compile-in-subprocess)
(macroexp--tests-dynamic-variable-p): Add tests.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/eval.c b/src/eval.c
index fe29564aa2d..ddf455e4d78 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2608,6 +2608,19 @@ eval_sub (Lisp_Object form)
              interpreted using lexical-binding or not.  */
           specbind (Qlexical_binding,
                     NILP (Vinternal_interpreter_environment) ? Qnil : Qt);
+
+          /* Make the macro aware of any defvar declarations in scope. */
+          Lisp_Object dynvars = Vmacroexp__dynvars;
+          for (Lisp_Object p = Vinternal_interpreter_environment;
+               !NILP (p); p = XCDR(p))
+            {
+              Lisp_Object e = XCAR (p);
+              if (SYMBOLP (e))
+                dynvars = Fcons(e, dynvars);
+            }
+          if (!EQ (dynvars, Vmacroexp__dynvars))
+            specbind (Qmacroexp__dynvars, dynvars);
+
           exp = apply1 (Fcdr (fun), original_args);
           exp = unbind_to (count1, exp);
           val = eval_sub (exp);