Expander warns about unbound variables.

* eval.c (eval_exception): New static function.
(eval_error): Reduced to wrapper around eval_exception.
(eval_warn): New function.
(me_op): Bind the rest symbol in a shadowing env to suppress
watnings about unbound rest.
(do_expand): Throw a warning when a bindable symbol is
traversed that has no binding.
(expand): Don't install atoms as last_form_expanded.

* lib.c (warning_s, restart_s, continue_s): New symbol
variables.
(obj_init): Initialize new symbol variables.

* lib.h (warning_s, restart_s, continue_s): Declared.

* lisplib.c (except_set_entries): New entries for
ignwarn and macro-time-ignwarn.

* parser.c (repl_warning): New static function.
(repl): Use repl_warning function as a handler for
warning exceptions: to print their message and then
continue by throwing a continue exception.

* parser.y (warning_continue): New static function.
(parse_once): Use warning_continue to ignore warnings.
In other words, we suppress warnings from Lisp that is
mixed into TXR pattern language code, because this
produces too many false positives.

* share/txr/stdlib/except.tl (ignwarn, macro-time-ignwarn):
New macros.

* share/txr/stdlib/place.tl (call-update-expander,
call-clobber-expander, call-delete-expander): Ignore warnings
around calls to sys:expand, because of some gensym-related
false positives (we expand code into which we inserted some
gensyms, without having inserted the constructs which
bind them.

* tests/011/macros-2.txr: Suppress unbound variable
warnings from a test case.

* tests/012/ifa.tl: Bind unbound x y variables in one
test case.

* tests/012/struct.tl: Suppress unbound variable
warnings in some test cases.

* uwind.c (uw_throw): If a warning is unhandled, then
print its message with a "warning" prefix and then
throw a continue exception.
(uw_register_subtype): Eliminate the check for sub
already being a subtype of sup. This allows us to
officially register new types against t.
(uw_late_init): Register continue exception type as a
subtype of the restart type.
Formally register warning type.

* txr.1: Documented ignwarn.

1 files changed, 9 insertions, 0 deletions

diff --git a/parser.y b/parser.y
index a6950e8f..c39b3a8f 100644
--- a/parser.y
+++ b/parser.y
@@ -1740,9 +1740,15 @@ void yybadtoken(parser_t *parser, int tok, val context)
         yyerrorf(scnr, lit("unexpected character ~a"), chr(tok), nao);
 }
 
+static val warning_continue(val exc, val arg)
+{
+  uw_throw(continue_s, nil);
+}
+
 int parse_once(val stream, val name, parser_t *parser)
 {
   int res = 0;
+  uw_frame_t uw_handler;
 #if CONFIG_DEBUG_SUPPORT
   debug_state_t ds = debug_set_state(opt_dbg_expansion ? 0 : -1,
                                      opt_dbg_expansion);
@@ -1753,6 +1759,7 @@ int parse_once(val stream, val name, parser_t *parser)
   parser->stream = stream;
   parser->name = name;
 
+  uw_push_handler(&uw_handler, cons(warning_s, nil), func_n2(warning_continue));
 
   uw_catch_begin(cons(error_s, nil), esym, eobj);
 
@@ -1774,6 +1781,8 @@ int parse_once(val stream, val name, parser_t *parser)
 
   uw_catch_end;
 
+  uw_pop_frame(&uw_handler);
+
   return res;
 }