From 7728e093378d1ef0e7fb0e633ed26c036f896766 Mon Sep 17 00:00:00 2001
From: Dianne Skoll <dianne@skoll.ca>
Date: Thu, 30 May 2024 12:27:35 -0400
Subject: [PATCH] Don't allow duplicate arg names in function definitions.

---
 src/err.h     |  4 +++-
 src/userfns.c | 11 +++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/err.h b/src/err.h
index a0388bc6..f957d2ee 100644
--- a/src/err.h
+++ b/src/err.h
@@ -122,6 +122,7 @@
 #define E_TIME_TWICE        102
 #define E_DURATION_NO_AT    103
 #define E_EXPECTING_WEEKDAY 104
+#define E_REPEATED_ARG      105
 
 #ifdef MK_GLOBALS
 #undef EXTERN
@@ -244,7 +245,8 @@ EXTERN char *ErrMsg[]
     "String too long",
     "Time specified twice",
     "Cannot specify DURATION without specifying AT",
-    "Expecting weekday name"
+    "Expecting weekday name",
+    "Duplicate argument name"
 }
 #endif /* MK_GLOBALS */
 ;
diff --git a/src/userfns.c b/src/userfns.c
index a8a27788..a267ebea 100644
--- a/src/userfns.c
+++ b/src/userfns.c
@@ -100,6 +100,7 @@ int DoFset(ParsePtr p)
     int c;
     UserFunc *func;
     Var *v;
+    Var *local;
     int orig_namelen;
 
     DynamicBuffer buf;
@@ -168,6 +169,16 @@ int DoFset(ParsePtr p)
 		DestroyUserFunc(func);
 		return E_BAD_ID;
 	    }
+            /* If we've already seen this local variable, error */
+            local = func->locals;
+            while(local) {
+                if (!StrinCmp(DBufValue(&buf), local->name, VAR_NAME_LEN)) {
+                    DBufFree(&buf);
+                    DestroyUserFunc(func);
+                    return E_REPEATED_ARG;
+                }
+                local = local->next;
+            }
 	    v = NEW(Var);
 	    if (!v) {
 		DBufFree(&buf);