handle non-null, but empty NestingMap in a set

plans/objchange/objchange.go

@@ -333,8 +333,9 @@ func setElementCompareValue(schema *configschema.Block, v cty.Value, isConfig bo
 	}
 
 	for name, blockType := range schema.BlockTypes {
-		switch blockType.Nesting {
+		elementType := blockType.Block.ImpliedType()
 
+		switch blockType.Nesting {
 		case configschema.NestingSingle, configschema.NestingGroup:
 			attrs[name] = setElementCompareValue(&blockType.Block, v.GetAttr(name), isConfig)
 
@@ -361,7 +362,7 @@ func setElementCompareValue(schema *configschema.Block, v cty.Value, isConfig bo
 					attrs[name] = cty.SetVal(elems)
 
 				// NestingList cases
-				case blockType.Block.ImpliedType().HasDynamicTypes():
+				case elementType.HasDynamicTypes():
 					attrs[name] = cty.TupleVal(elems)
 				default:
 					attrs[name] = cty.ListVal(elems)
@@ -369,19 +370,19 @@ func setElementCompareValue(schema *configschema.Block, v cty.Value, isConfig bo
 			} else {
 				switch {
 				case blockType.Nesting == configschema.NestingSet:
-					attrs[name] = cty.SetValEmpty(blockType.Block.ImpliedType())
+					attrs[name] = cty.SetValEmpty(elementType)
 
 				// NestingList cases
-				case blockType.Block.ImpliedType().HasDynamicTypes():
+				case elementType.HasDynamicTypes():
 					attrs[name] = cty.EmptyTupleVal
 				default:
-					attrs[name] = cty.ListValEmpty(blockType.Block.ImpliedType())
+					attrs[name] = cty.ListValEmpty(elementType)
 				}
 			}
 
 		case configschema.NestingMap:
 			cv := v.GetAttr(name)
-			if cv.IsNull() || !cv.IsKnown() {
+			if cv.IsNull() || !cv.IsKnown() || cv.LengthInt() == 0 {
 				attrs[name] = cv
 				continue
 			}
@@ -390,8 +391,9 @@ func setElementCompareValue(schema *configschema.Block, v cty.Value, isConfig bo
 				kv, ev := it.Element()
 				elems[kv.AsString()] = setElementCompareValue(&blockType.Block, ev, isConfig)
 			}
+
 			switch {
-			case blockType.Block.ImpliedType().HasDynamicTypes():
+			case elementType.HasDynamicTypes():
 				attrs[name] = cty.ObjectVal(elems)
 			default:
 				attrs[name] = cty.MapVal(elems)

plans/objchange/objchange_test.go

@@ -799,6 +799,61 @@ func TestProposedNewObject(t *testing.T) {
 				}),
 			}),
 		},
+		"empty nested map in set": {
+			&configschema.Block{
+				BlockTypes: map[string]*configschema.NestedBlock{
+					"foo": {
+						Nesting: configschema.NestingSet,
+						Block: configschema.Block{
+							BlockTypes: map[string]*configschema.NestedBlock{
+								"bar": {
+									Nesting: configschema.NestingMap,
+									Block: configschema.Block{
+										Attributes: map[string]*configschema.Attribute{
+											"baz": {
+												Type:     cty.String,
+												Optional: true,
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			cty.ObjectVal(map[string]cty.Value{
+				"foo": cty.SetVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"bar": cty.MapValEmpty(cty.Object(map[string]cty.Type{
+							"baz": cty.String,
+						})),
+					}),
+				}),
+			}),
+			cty.ObjectVal(map[string]cty.Value{
+				"foo": cty.SetVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"bar": cty.MapVal(map[string]cty.Value{
+							"bing": cty.ObjectVal(map[string]cty.Value{
+								"baz": cty.StringVal("true"),
+							}),
+						}),
+					}),
+				}),
+			}),
+			cty.ObjectVal(map[string]cty.Value{
+				"foo": cty.SetVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"bar": cty.MapVal(map[string]cty.Value{
+							"bing": cty.ObjectVal(map[string]cty.Value{
+								"baz": cty.StringVal("true"),
+							}),
+						}),
+					}),
+				}),
+			}),
+		},
 	}
 
 	for name, test := range tests {