fixup! function/stdlib: LookupFunc precise handling of marks

cty/function/stdlib/collection.go

@@ -683,30 +683,36 @@ var LookupFunc = function.New(&function.Spec{
 		// leave default value marked
 		defaultVal := args[2]
 
+		var markses []cty.ValueMarks
+
 		// unmark collection, retain marks to reapply later
-		mapVar, marks := args[0].Unmark()
+		mapVar, mapMarks := args[0].Unmark()
+		markses = append(markses, mapMarks)
 
-		// disregard marks on the key
-		keyVal, _ := args[1].Unmark()
+		// include marks on the key in the result
+		keyVal, keyMarks := args[1].Unmark()
+		if len(keyMarks) > 0 {
+			markses = append(markses, keyMarks)
+		}
 		lookupKey := keyVal.AsString()
 
 		if !mapVar.IsWhollyKnown() {
-			return cty.UnknownVal(retType).WithMarks(marks), nil
+			return cty.UnknownVal(retType).WithMarks(markses...), nil
 		}
 
 		if mapVar.Type().IsObjectType() {
 			if mapVar.Type().HasAttribute(lookupKey) {
-				return mapVar.GetAttr(lookupKey).WithMarks(marks), nil
+				return mapVar.GetAttr(lookupKey).WithMarks(markses...), nil
 			}
 		} else if mapVar.HasIndex(cty.StringVal(lookupKey)) == cty.True {
-			return mapVar.Index(cty.StringVal(lookupKey)).WithMarks(marks), nil
+			return mapVar.Index(cty.StringVal(lookupKey)).WithMarks(markses...), nil
 		}
 
 		defaultVal, err = convert.Convert(defaultVal, retType)
 		if err != nil {
 			return cty.NilVal, err
 		}
-		return defaultVal.WithMarks(marks), nil
+		return defaultVal.WithMarks(markses...), nil
 	},
 })
 

cty/function/stdlib/collection_test.go

@@ -1080,14 +1080,14 @@ func TestLookup(t *testing.T) {
 			cty.NumberIntVal(5).Mark("c"),
 			cty.StringVal("5").Mark("c"),
 		},
-		{ // disregard marks on key
+		{ // propagate marks from key
 			cty.MapVal(map[string]cty.Value{
 				"boop": cty.StringVal("beep"),
 				"frob": cty.StringVal("honk"),
 			}),
 			cty.StringVal("boop").Mark("a"),
 			cty.StringVal("nope"),
-			cty.StringVal("beep"),
+			cty.StringVal("beep").Mark("a"),
 		},
 	}