Preserve marks when traversing unknown values

When traversing an unknown value or a DynamicVal, the marks from that
initial value must be preserved for HCL Index and GetAttr operations.
This mirrors the behavior of GetAttr and Index when used directly the
underlying cty values.

Author: jbardin

ops.go

@@ -49,7 +49,7 @@ func Index(collection, key cty.Value, srcRange *Range) (cty.Value, Diagnostics)
 	ty := collection.Type()
 	kty := key.Type()
 	if kty == cty.DynamicPseudoType || ty == cty.DynamicPseudoType {
-		return cty.DynamicVal, nil
+		return cty.DynamicVal.WithSameMarks(collection), nil
 	}
 
 	switch {
@@ -87,9 +87,9 @@ func Index(collection, key cty.Value, srcRange *Range) (cty.Value, Diagnostics)
 		has, _ := collection.HasIndex(key).Unmark()
 		if !has.IsKnown() {
 			if ty.IsTupleType() {
-				return cty.DynamicVal, nil
+				return cty.DynamicVal.WithSameMarks(collection), nil
 			} else {
-				return cty.UnknownVal(ty.ElementType()), nil
+				return cty.UnknownVal(ty.ElementType()).WithSameMarks(collection), nil
 			}
 		}
 		if has.False() {
@@ -196,10 +196,10 @@ func Index(collection, key cty.Value, srcRange *Range) (cty.Value, Diagnostics)
 			}
 		}
 		if !collection.IsKnown() {
-			return cty.DynamicVal, nil
+			return cty.DynamicVal.WithSameMarks(collection), nil
 		}
 		if !key.IsKnown() {
-			return cty.DynamicVal, nil
+			return cty.DynamicVal.WithSameMarks(collection), nil
 		}
 
 		key, _ = key.Unmark()
@@ -291,13 +291,13 @@ func GetAttr(obj cty.Value, attrName string, srcRange *Range) (cty.Value, Diagno
 		}
 
 		if !obj.IsKnown() {
-			return cty.UnknownVal(ty.AttributeType(attrName)), nil
+			return cty.UnknownVal(ty.AttributeType(attrName)).WithSameMarks(obj), nil
 		}
 
 		return obj.GetAttr(attrName), nil
 	case ty.IsMapType():
 		if !obj.IsKnown() {
-			return cty.UnknownVal(ty.ElementType()), nil
+			return cty.UnknownVal(ty.ElementType()).WithSameMarks(obj), nil
 		}
 
 		idx := cty.StringVal(attrName)
@@ -319,7 +319,7 @@ func GetAttr(obj cty.Value, attrName string, srcRange *Range) (cty.Value, Diagno
 
 		return obj.Index(idx), nil
 	case ty == cty.DynamicPseudoType:
-		return cty.DynamicVal, nil
+		return cty.DynamicVal.WithSameMarks(obj), nil
 	case ty.IsListType() && ty.ElementType().IsObjectType():
 		// It seems a common mistake to try to access attributes on a whole
 		// list of objects rather than on a specific individual element, so

ops_test.go

@@ -249,6 +249,113 @@ func TestApplyPath(t *testing.T) {
 			cty.NilVal,
 			`Attempt to get attribute from null value: This value is null, so it does not have any attributes.`,
 		},
+
+		// Marks should be retained during index and getattr ops, even when
+		// types and values are unknown. This reflects the same behavior when
+		// using cty to directly call GetAttr and Index methods.
+		{
+			cty.DynamicVal.Mark("marked"),
+			(cty.Path)(nil).GetAttr("foo"),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.ObjectVal(map[string]cty.Value{
+				"foo": cty.StringVal("should be marked"),
+			}).Mark("marked"),
+			(cty.Path)(nil).GetAttr("foo"),
+			cty.StringVal("should be marked").Mark("marked"),
+			``,
+		},
+		{
+			cty.UnknownVal(cty.Object(map[string]cty.Type{
+				"foo": cty.DynamicPseudoType,
+			})).Mark("marked"),
+			(cty.Path)(nil).GetAttr("foo"),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.DynamicVal.Mark("marked"),
+			(cty.Path)(nil).Index(cty.StringVal("foo")),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.ObjectVal(map[string]cty.Value{
+				"foo": cty.StringVal("should be marked"),
+			}).Mark("marked"),
+			(cty.Path)(nil).Index(cty.StringVal("foo")),
+			cty.StringVal("should be marked").Mark("marked"),
+			``,
+		},
+		{
+			cty.UnknownVal(cty.Object(map[string]cty.Type{
+				"foo": cty.DynamicPseudoType,
+			})).Mark("marked"),
+			(cty.Path)(nil).Index(cty.StringVal("foo")),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.DynamicVal.Mark("marked"),
+			(cty.Path)(nil).Index(cty.NumberIntVal(0)),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.ListVal([]cty.Value{cty.StringVal("should be marked")}).Mark("marked"),
+			(cty.Path)(nil).Index(cty.NumberIntVal(0)),
+			cty.StringVal("should be marked").Mark("marked"),
+			``,
+		},
+		{
+			cty.UnknownVal(cty.List(cty.String)).Mark("marked"),
+			(cty.Path)(nil).Index(cty.NumberIntVal(0)),
+			cty.UnknownVal(cty.String).Mark("marked"),
+			``,
+		},
+
+		{
+			cty.DynamicVal.Mark("marked"),
+			(cty.Path)(nil).Index(cty.UnknownVal(cty.String)),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.ObjectVal(map[string]cty.Value{
+				"foo": cty.StringVal("should be marked"),
+			}).Mark("marked"),
+			(cty.Path)(nil).Index(cty.UnknownVal(cty.String)),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.UnknownVal(cty.Object(map[string]cty.Type{
+				"foo": cty.DynamicPseudoType,
+			})).Mark("marked"),
+			(cty.Path)(nil).Index(cty.UnknownVal(cty.String)),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.DynamicVal.Mark("marked"),
+			(cty.Path)(nil).Index(cty.UnknownVal(cty.Number)),
+			cty.DynamicVal.Mark("marked"),
+			``,
+		},
+		{
+			cty.ListVal([]cty.Value{cty.StringVal("should be marked")}).Mark("marked"),
+			(cty.Path)(nil).Index(cty.UnknownVal(cty.Number)),
+			cty.UnknownVal(cty.String).Mark("marked"),
+			``,
+		},
+		{
+			cty.UnknownVal(cty.List(cty.String)).Mark("marked"),
+			(cty.Path)(nil).Index(cty.UnknownVal(cty.Number)),
+			cty.UnknownVal(cty.String).Mark("marked"),
+			``,
+		},
 	}
 
 	for _, test := range tests {
@@ -257,7 +364,7 @@ func TestApplyPath(t *testing.T) {
 			t.Logf("testing ApplyPath\nstart: %#v\npath:  %#v", test.Start, test.Path)
 
 			for _, diag := range diags {
-				t.Logf(diag.Error())
+				t.Log(diag.Error())
 			}
 
 			if test.WantErr != "" {