Fix Delete matching keys that contain a backslash

parser.go

@@ -109,12 +109,11 @@ func findKeyStartConfig(config Config, data []byte, key string) (int, error) {
 	if data[i] == '{' || data[i] == '[' {
 		i += 1
 	}
+	// key is compared as is against the unescaped JSON keys, the same way
+	// searchKeys matches the path for Get, Set and EachKey. It must not be
+	// unescaped itself, and must not share stackbuf with the JSON keys.
 	var stackbuf [unescapeStackBufSize]byte // stack-allocated array for allocation-free unescaping of small strings
 
-	if ku, err := unescapeConfig(config, StringToBytes(key), stackbuf[:]); err == nil {
-		key = bytesToString(&ku)
-	}
-
 	for i < ln {
 		switch data[i] {
 		case '"', '\'':

parser_test.go

@@ -264,6 +264,40 @@ var deleteTests = []DeleteTest{
 		path: []string{"test"},
 		data: `}`,
 	},
+	{
+		// The path is matched against the unescaped JSON key, as in Get.
+		desc: "Delete key with simple escape",
+		json: `{"a\\b":1,"c":2}`,
+		path: []string{"a\\b"},
+		data: `{"c":2}`,
+	},
+	{
+		desc: "Delete key with Unicode escape",
+		json: `{"c":2,"a\u00B0b":1}`,
+		path: []string{"a\u00B0b"},
+		data: `{"c":2}`,
+	},
+	{
+		// The backslash in the path must not make an earlier escaped key
+		// of the same length match: this used to delete everything from
+		// "\"q" to the end, "keep" included.
+		desc: "Delete escaped key must not match an earlier escaped key",
+		json: `{"\"q":1,"keep":0,"a\\b":2}`,
+		path: []string{"a\\b"},
+		data: `{"\"q":1,"keep":0}`,
+	},
+	{
+		desc: "Delete nested escaped key must not match an earlier escaped key",
+		json: `{"x":{"D:\\xyzw":1,"C:\\temp":2}}`,
+		path: []string{"x", "C:\\temp"},
+		data: `{"x":{"D:\\xyzw":1}}`,
+	},
+	{
+		desc: "Delete with a path that is only equal to the escaped form of a key",
+		json: `{"a\u00B0b":1}`,
+		path: []string{"a\\u00B0b"},
+		data: `{"a\u00B0b":1}`,
+	},
 }
 
 var setTests = []SetTest{