Add back constraint that direct dict->list conversion is only done when no string representation exists.pyk_listdictstringrep

2 files changed, 16 insertions, 6 deletions

diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index 0852c8c..362efa2 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -1827,11 +1827,6 @@ SetListFromAny(
     List *listRepPtr;
     Tcl_Obj **elemPtrs;
 
-    /*
-     * Dictionaries are a special case; they may have stored a previous list
-     * representation
-     */
-
      listPtr = TclObjLookupTyped(objPtr, &tclListType);
      if (listPtr != NULL) {
 	Tcl_IncrRefCount(listPtr);
@@ -1844,7 +1839,15 @@ SetListFromAny(
 	return TCL_OK;
      }
 
-    if (objPtr->typePtr == &tclDictType) {
+    /*
+     * Dictionaries are a special case; they have a string representation such
+     * that *all* valid dictionaries are valid lists. Hence we can convert
+     * more directly. Only do this when there's no existing string rep; if
+     * there is, it is the string rep that's authoritative (because it could
+     * describe duplicate keys).
+     */
+
+    if (objPtr->typePtr == &tclDictType && !objPtr->bytes) {
 	Tcl_Obj *keyPtr, *valuePtr;
 	Tcl_DictSearch search;
 	int done, size;
diff --git a/tests/list.test b/tests/list.test
index dff5d50..661ddde 100644
--- a/tests/list.test
+++ b/tests/list.test
@@ -129,6 +129,13 @@ test list-4.1 {Bug 3173086} {
     string is list "{[list \\\\\}]}"
 } 1
 
+test list-5.1 {list/dict conversions without} {
+	 set a {a 1 a 2}
+	 dict get $a a
+	 lindex $a 1
+} 1
+	
+
 # cleanup
 ::tcltest::cleanupTests
 return