(struct ...) with duped keys will use last value.

CHANGELOG.md

@@ -2,6 +2,8 @@
 All notable changes to this project will be documented in this file.
 
 ## Unreleased - ???
+- A struct/table literal/constructor with duplicate keys will use the last value given.
+  Previously, this was inconsistent between tables and structs, literals and constructor functions.
 - Add debugger to core. The debugger functions are only available
   in a debug repl, and are prefixed by a `.`.
 - Add `sort-by` and `sorted-by` to core.

src/core/parse.c

@@ -437,21 +437,23 @@ static Janet close_array(JanetParser *p, JanetParseState *state) {
 
 static Janet close_struct(JanetParser *p, JanetParseState *state) {
     JanetKV *st = janet_struct_begin(state->argn >> 1);
-    for (int32_t i = state->argn; i > 0; i -= 2) {
-        Janet value = p->args[--p->argcount];
-        Janet key = p->args[--p->argcount];
+    for (size_t i = p->argcount - state->argn; i < p->argcount; i += 2) {
+        Janet key = p->args[i];
+        Janet value = p->args[i + 1];
         janet_struct_put(st, key, value);
     }
+    p->argcount -= state->argn;
     return janet_wrap_struct(janet_struct_end(st));
 }
 
 static Janet close_table(JanetParser *p, JanetParseState *state) {
     JanetTable *table = janet_table(state->argn >> 1);
-    for (int32_t i = state->argn; i > 0; i -= 2) {
-        Janet value = p->args[--p->argcount];
-        Janet key = p->args[--p->argcount];
+    for (size_t i = p->argcount - state->argn; i < p->argcount; i += 2) {
+        Janet key = p->args[i];
+        Janet value = p->args[i + 1];
         janet_table_put(table, key, value);
     }
+    p->argcount -= state->argn;
     return janet_wrap_table(table);
 }
 

src/core/struct.c

@@ -123,7 +123,8 @@ void janet_struct_put(JanetKV *st, Janet key, Janet value) {
                 dist = otherdist;
                 hash = otherhash;
             } else if (status == 0) {
-                /* A key was added to the struct more than once */
+                /* A key was added to the struct more than once - replace old value */
+                kv->value = value;
                 return;
             }
         }

test/suite0.janet

@@ -328,5 +328,11 @@
 (assert (= true ;(map truthy? [0 "" true @{} {} [] '()])) "truthy values")
 (assert (= false ;(map truthy? [nil false])) "non-truthy values")
 
+# Struct and Table duplicate elements
+(assert (= {:a 3 :b 2} {:a 1 :b 2 :a 3}) "struct literal duplicate keys")
+(assert (= {:a 3 :b 2} (struct :a 1 :b 2 :a 3)) "struct constructor duplicate keys")
+(assert (deep= @{:a 3 :b 2} @{:a 1 :b 2 :a 3}) "table literal duplicate keys")
+(assert (deep= @{:a 3 :b 2} (table :a 1 :b 2 :a 3)) "table constructor duplicate keys")
+
 (end-suite)