bugfix: quasilit read/print consistency, part 2.

In this patch commit I'm addressing the issue introduced in
part 1 that expressions in @(output) blocks are still using
(sys:expr ...) wrapping, but are passed down to an evaluator
which now expects unwrapped expressions now.

As part of this change, I'm changing the representation of
@expr from (sys:expr . expr) to (sys:expr expr).

* eval.c (format_field): Adjust access to sys:expr
expression based on new representation.
(transform_op): Likewise.

* lib.c (obj_print_impl): Likewise.

* match.c (dest_bind): Likewise.
(do_txeval): Likewise.
(do_output_line): Likewise, in some compat code.  Here is the
fix for the issue: when calling tx_subst_vars, we pass a list
of one element containing the expression, not wrapped in
sys:expr. Previously, we passed a one-element list containing
the sys:expr.

* parser.y (o_elem): If a list occurs in the syntax, represent
it as (sys:expr list) rather than (sys:expr . list).
(list): Do the same for @ n_expr syntax.
(expand_meta, make_expr): Harmonize with the representation
change.

1 files changed, 3 insertions, 3 deletions

diff --git a/eval.c b/eval.c
index 6fe12132..51fcdb4b 100644
--- a/eval.c
+++ b/eval.c
@@ -2249,7 +2249,7 @@ val format_field(val obj, val modifier, val filter, val eval_fun)
     } else if ((!opt_compat || opt_compat > 128) &&
                consp(item) && car(item) == expr_s)
     {
-      item = cdr(item);
+      item = cadr(item);
       goto eval;
     } else if (consp(item) && car(item) == dwim_s) {
       val arg_expr = second(item);
@@ -3034,8 +3034,8 @@ static val transform_op(val forms, val syms, val rg)
     val fi = first(forms);
     val re = rest(forms);
 
-    if (fi == expr_s && meta_meta_p(re))
-      return cons(syms, rlcp(meta_meta_strip(re), forms));
+    if (fi == expr_s && meta_meta_p(car(re)))
+      return cons(syms, rlcp(meta_meta_strip(car(re)), forms));
 
     /* This handles improper list forms like (a b c . @42)
        when the recursion hits the @42 part. */