From 94e5a6b6ce7ad4b103e9d55c1aad2bd376f5da67 Mon Sep 17 00:00:00 2001
From: Eduardo Julian
Date: Thu, 17 Oct 2019 20:51:39 -0400
Subject: FIX old compiler could allow aliases to be defined more than once

---
 luxc/src/lux/analyser/lux.clj | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

(limited to 'luxc/src')

diff --git a/luxc/src/lux/analyser/lux.clj b/luxc/src/lux/analyser/lux.clj
index eb412bf0c..fee56b624 100644
--- a/luxc/src/lux/analyser/lux.clj
+++ b/luxc/src/lux/analyser/lux.clj
@@ -541,12 +541,15 @@
   (|do [output (analyse-function** analyse exo-type ?self ?arg ?body)]
     (return (&/|list output))))
 
+(defn ^:private ensure-undefined! [module-name local-name]
+  (|do [verdict (&&module/defined? module-name local-name)]
+    (&/assert! (not verdict)
+               (str "[Analyser Error] Cannot re-define " module-name &/+name-separator+ local-name))))
+
 (defn analyse-def* [analyse optimize eval! compile-def ?name ?value ?meta exported? & [?expected-type]]
   (|do [_ &/ensure-directive
         module-name &/get-module-name
-        ? (&&module/defined? module-name ?name)
-        _ (&/assert! (not ?)
-                     (str "[Analyser Error] Cannot re-define " (str module-name &/+name-separator+ ?name)))
+        _ (ensure-undefined! module-name ?name)
         =value (&/without-repl-closure
                 (&/with-scope ?name
                   (if ?expected-type
@@ -580,8 +583,9 @@
 
 (defn analyse-def-alias [?alias ?original]
   (|let [[r-module r-name] ?original]
-    (|do [_ (&&module/find-def r-module r-name)
-          module-name &/get-module-name
+    (|do [module-name &/get-module-name
+          _ (ensure-undefined! module-name ?alias)
+          _ (&&module/find-def r-module r-name)
           _ (&/without-repl-closure
              (&&module/define-alias module-name ?alias ?original))]
       (return &/$Nil))))
-- 
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