wip: Reduce test differences [ci-skip]

 - Handle UTF-16 surrogate pairs
 - Handle cycles in values
 - Handle cycles in types
 - Better errors
 - Handle case-folding of struct field names
 - Allow []byteTypeWithMethods
 - Fix struct field-order
 - Fix handling of interfaces storing pointers
 - Enforce a maximum decode depth
 - Validate struct tags

1 files changed, 38 insertions, 23 deletions

diff --git a/struct.go b/struct.go
index ad142d6..ee2bbf3 100644
--- a/struct.go
+++ b/struct.go
@@ -22,24 +22,24 @@ type structIndex struct {
 }
 
 func indexStruct(typ reflect.Type) structIndex {
-	byName := make(map[string][]structField)
-	var byPos []string
+	var byPos []structField
+	byName := make(map[string][]int)
 
-	indexStructInner(typ, nil, byName, &byPos)
+	indexStructInner(typ, nil, &byPos, byName, map[reflect.Type]struct{}{})
 
 	ret := structIndex{
 		byName: make(map[string]int),
 	}
 
-	for _, name := range byPos {
-		fields := byName[name]
-		delete(byName, name)
-		switch len(fields) {
+	for curPos, _field := range byPos {
+		name := _field.Name
+		fieldPoss := byName[name]
+		switch len(fieldPoss) {
 		case 0:
 			// do nothing
 		case 1:
 			ret.byName[name] = len(ret.byPos)
-			ret.byPos = append(ret.byPos, fields[0])
+			ret.byPos = append(ret.byPos, _field)
 		default:
 			// To quote the encoding/json docs (version 1.18.4):
 			//
@@ -56,27 +56,29 @@ func indexStruct(typ reflect.Type) structIndex {
 			//
 			//    3) Otherwise there are multiple fields, and all are ignored; no error
 			//       occurs.
-			leastLevel := len(fields[0].Path)
-			for _, field := range fields[1:] {
+			leastLevel := len(byPos[fieldPoss[0]].Path)
+			for _, fieldPos := range fieldPoss[1:] {
+				field := byPos[fieldPos]
 				if len(field.Path) < leastLevel {
 					leastLevel = len(field.Path)
 				}
 			}
 			var numUntagged, numTagged int
-			var untaggedIdx, taggedIdx int
-			for i, field := range fields {
+			var untaggedPos, taggedPos int
+			for _, fieldPos := range fieldPoss {
+				field := byPos[fieldPos]
 				if len(field.Path) != leastLevel {
 					continue
 				}
 				if field.Tagged {
 					numTagged++
-					taggedIdx = i
+					taggedPos = fieldPos
 					if numTagged > 1 {
 						break // optimization
 					}
 				} else {
 					numUntagged++
-					untaggedIdx = i
+					untaggedPos = fieldPos
 				}
 			}
 			switch numTagged {
@@ -85,12 +87,16 @@ func indexStruct(typ reflect.Type) structIndex {
 				case 0:
 					// do nothing
 				case 1:
-					ret.byName[name] = len(ret.byPos)
-					ret.byPos = append(ret.byPos, fields[untaggedIdx])
+					if curPos == untaggedPos {
+						ret.byName[name] = len(ret.byPos)
+						ret.byPos = append(ret.byPos, byPos[curPos])
+					}
 				}
 			case 1:
-				ret.byName[name] = len(ret.byPos)
-				ret.byPos = append(ret.byPos, fields[taggedIdx])
+				if curPos == taggedPos {
+					ret.byName[name] = len(ret.byPos)
+					ret.byPos = append(ret.byPos, byPos[curPos])
+				}
 			}
 		}
 	}
@@ -98,7 +104,13 @@ func indexStruct(typ reflect.Type) structIndex {
 	return ret
 }
 
-func indexStructInner(typ reflect.Type, prefix []int, byName map[string][]structField, byPos *[]string) {
+func indexStructInner(typ reflect.Type, prefix []int, byPos *[]structField, byName map[string][]int, seen map[reflect.Type]struct{}) {
+	if _, ok := seen[typ]; ok {
+		return
+	}
+	seen[typ] = struct{}{}
+	defer delete(seen, typ)
+
 	n := typ.NumField()
 	for i := 0; i < n; i++ {
 		path := append(append([]int(nil), prefix...), i)
@@ -123,25 +135,28 @@ func indexStructInner(typ reflect.Type, prefix []int, byName map[string][]struct
 		}
 		tagName, opts := parseTag(tag)
 		name := tagName
+		if !isValidTag(name) {
+			name = ""
+		}
 		if name == "" {
 			name = fTyp.Name
 		}
 
-		if embed {
+		if embed && tagName == "" {
 			t := fTyp.Type
 			if t.Kind() == reflect.Pointer {
 				t = t.Elem()
 			}
-			indexStructInner(t, path, byName, byPos)
+			indexStructInner(t, path, byPos, byName, seen)
 		} else {
-			byName[name] = append(byName[name], structField{
+			byName[name] = append(byName[name], len(*byPos))
+			*byPos = append(*byPos, structField{
 				Name:      name,
 				Path:      path,
 				Tagged:    tagName != "",
 				OmitEmpty: opts.Contains("omitempty"),
 				Quote:     opts.Contains("string") && isQuotable(fTyp.Type),
 			})
-			*byPos = append(*byPos, name)
 		}
 	}
 }