Merge pull request #10 from brunoga/pointer_map_fix

Correctly handle 2 values with different types but same pointers.

deep.go

@@ -30,6 +30,8 @@ func MustCopy[T any](src T) T {
 	return dst
 }
 
+type pointersMap map[uintptr]map[string]reflect.Value
+
 func copy[T any](src T, skipUnsupported bool) (T, error) {
 	v := reflect.ValueOf(src)
 
@@ -41,7 +43,7 @@ func copy[T any](src T, skipUnsupported bool) (T, error) {
 		return t, nil
 	}
 
-	dst, err := recursiveCopy(v, make(map[uintptr]reflect.Value),
+	dst, err := recursiveCopy(v, make(pointersMap),
 		skipUnsupported)
 	if err != nil {
 		var t T
@@ -51,7 +53,7 @@ func copy[T any](src T, skipUnsupported bool) (T, error) {
 	return dst.Interface().(T), nil
 }
 
-func recursiveCopy(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopy(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	switch v.Kind() {
 	case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
@@ -93,7 +95,7 @@ func recursiveCopy(v reflect.Value, pointers map[uintptr]reflect.Value,
 	}
 }
 
-func recursiveCopyArray(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopyArray(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	dst := reflect.New(v.Type()).Elem()
 
@@ -110,7 +112,7 @@ func recursiveCopyArray(v reflect.Value, pointers map[uintptr]reflect.Value,
 	return dst, nil
 }
 
-func recursiveCopyInterface(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopyInterface(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	if v.IsNil() {
 		// If the interface is nil, just return it.
@@ -120,7 +122,7 @@ func recursiveCopyInterface(v reflect.Value, pointers map[uintptr]reflect.Value,
 	return recursiveCopy(v.Elem(), pointers, skipUnsupported)
 }
 
-func recursiveCopyMap(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopyMap(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	if v.IsNil() {
 		// If the slice is nil, just return it.
@@ -143,22 +145,31 @@ func recursiveCopyMap(v reflect.Value, pointers map[uintptr]reflect.Value,
 	return dst, nil
 }
 
-func recursiveCopyPtr(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopyPtr(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	// If the pointer is nil, just return it.
 	if v.IsNil() {
 		return v, nil
 	}
 
+	typeName := v.Type().String()
+
 	// If the pointer is already in the pointers map, return it.
 	ptr := v.Pointer()
-	if dst, ok := pointers[ptr]; ok {
-		return dst, nil
+	if dstMap, ok := pointers[ptr]; ok {
+		if dst, ok := dstMap[typeName]; ok {
+			return dst, nil
+		}
 	}
 
 	// Otherwise, create a new pointer and add it to the pointers map.
 	dst := reflect.New(v.Type().Elem())
-	pointers[ptr] = dst
+
+	if pointers[ptr] == nil {
+		pointers[ptr] = make(map[string]reflect.Value)
+	}
+
+	pointers[ptr][typeName] = dst
 
 	// Proceed with the copy.
 	elem := v.Elem()
@@ -172,7 +183,7 @@ func recursiveCopyPtr(v reflect.Value, pointers map[uintptr]reflect.Value,
 	return dst, nil
 }
 
-func recursiveCopySlice(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopySlice(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	if v.IsNil() {
 		// If the slice is nil, just return it.
@@ -195,7 +206,7 @@ func recursiveCopySlice(v reflect.Value, pointers map[uintptr]reflect.Value,
 	return dst, nil
 }
 
-func recursiveCopyStruct(v reflect.Value, pointers map[uintptr]reflect.Value,
+func recursiveCopyStruct(v reflect.Value, pointers pointersMap,
 	skipUnsupported bool) (reflect.Value, error) {
 	dst := reflect.New(v.Type()).Elem()
 

deep_test.go

@@ -340,3 +340,18 @@ func BenchmarkCopy_Deep(b *testing.B) {
 		MustCopy(src)
 	}
 }
+
+func TestTrickyMemberPointer(t *testing.T) {
+	type Foo struct {
+		N int
+	}
+	type Bar struct {
+		F *Foo
+		P *int
+	}
+
+	foo := Foo{N: 1}
+	bar := Bar{F: &foo, P: &foo.N}
+
+	doCopyAndCheck(t, bar, false)
+}