In backquote subshells, double quotes seem to disappear

[Niols]

Consider the script:

echo `echo "`

It's not clear to me whether this should be accepted (with the command echo " inside the subshell) or rejected (because of unterminated quotes). Dash rejects it complaining about unterminated quotes.

Morbig does accept it, but the double quotes seem to have disappeared. Whether it should be accepted or not, the output is wrong. Here is the simple json:

[
  "Command_SimpleCommand",
  [
    "SimpleCommand_CmdName_CmdSuffix",
    [
      "CmdName_Word",
      [ "Word", "echo", [ [ "WordName", "echo" ] ] ]
    ],
    [
      "CmdSuffix_Word",
      [
        "Word",
        "`echo \"`",
        [
          [
            "WordSubshell",
            [ "SubShellKindBackQuote" ],
            [
              "Program_LineBreak_CompleteCommands_LineBreak",
              [ "LineBreak_Empty" ],
              [
                "CompleteCommands_CompleteCommand",
                [
                  "CompleteCommand_CList",
                  [
                    "CList_AndOr",
                    [
                      "AndOr_Pipeline",
                      [
                        "Pipeline_PipeSequence",
                        [
                          "PipeSequence_Command",
                          [
                            "Command_SimpleCommand",
                            [
                              "SimpleCommand_CmdName",
                              [
                                "CmdName_Word",
                                [
                                  "Word",
                                  "echo",
                                  [ [ "WordName", "echo" ] ]
                                ]
                              ]
                            ]
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ],
              [ "LineBreak_Empty" ]
            ]
          ]
        ]
      ]
    ]
  ]
]