unuse-sym: fix in face of use-sym-as.

* lib.c (unuse_sym): A used symbol may now appear in a package
under a different name. So if we don't find a symbol under
the symbol's name, or find a different symbol, we must try
a reverse hash search before giving up.

* txr.1: Add notes to use-sym-as that unuse-sym must be
used to undo its effect. Add notes to unuse-sym discussing
similarities and differences versus unintern.

* tests/012/use-as.tl: New test cases.

1 files changed, 10 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index d7a7ce66..e5d01387 100644
--- a/lib.c
+++ b/lib.c
@@ -7359,6 +7359,16 @@ val unuse_sym(val symbol, val package_in)
   val visible = cdr(found_visible);
   val hidden = cdr(found_hidden);
 
+  if (!found_visible || visible != symbol) {
+    name = hash_revget(package->pk.symhash, symbol, eq_f, identity_f);
+    if (name) {
+      found_visible = gethash_e(self, package->pk.symhash, name);
+      found_hidden = gethash_e(self, package->pk.hidhash, name);
+      visible = cdr(found_visible);
+      hidden = cdr(found_hidden);
+    }
+  }
+
   if (!found_visible || visible != symbol)
     return nil;