[Glimmer 2] invalid inlineclassNameBindings inlink-to yields an exception

[GavinJoyce]

The invalid classNameBindings below behaves inconsistently in htmlbars and glimmer (see https://github.com/GavinJoyce/glammer/blob/master/app/templates/issue1.hbs).

{{#link-to 'index' classNameBindings="someProperty"}}

htmlbars:

no warning, the follow is rendered:

<a id="ember369" href="/" class="  ember-view">Click me to go to the index</a>

glimmer:

an exception is thrown when rendering:

Cannot read property '0' of null (in hasHelper)

Some questions:

• Should glimmer 2 behave the same as htmlbars?
• Should we issue a warning in development mode?

[rwjblue]

We should issue a helpful assertion. Ideally in both engines.

[GavinJoyce]

Thanks, I can take this on

[GavinJoyce]

TL;DR: it looks like we're generating an incorrect spec

---

For the template:

{{foo-bar classNameBindings="someInitiallyTrueProperty isBig:big:small"}}

Here's the processed AST (with loc info removed):

{
  "type": "Program",
  "body": [
    {
      "type": "MustacheStatement",
      "path": {
        "type": "PathExpression",
        "data": false,
        "original": "foo-bar",
        "parts": [
          "foo-bar"
        ]
      },
      "params": [],
      "hash": {
        "type": "Hash",
        "pairs": [
          {
            "type": "HashPair",
            "key": "class",
            "value": {
              "type": "SubExpression",
              "path": {
                "type": "PathExpression",
                "original": "concat",
                "parts": [
                  "concat"
                ],
                "data": false
              },
              "params": [
                {
                  "type": "SubExpression",
                  "path": {
                    "type": "PathExpression",
                    "original": "if",
                    "parts": [
                      "if"
                    ],
                    "data": false
                  },
                  "params": [
                    {
                      "type": "PathExpression",
                      "original": "someInitiallyTrueProperty",
                      "parts": [
                        "someInitiallyTrueProperty"
                      ],
                      "data": false
                    },
                    {
                      "type": "SubExpression",
                      "path": {
                        "type": "StringLiteral",
                        "value": "-normalize-class",
                        "original": "-normalize-class"
                      },
                      "params": [
                        {
                          "type": "StringLiteral",
                          "value": "someInitiallyTrueProperty",
                          "original": "someInitiallyTrueProperty"
                        },
                        {
                          "type": "PathExpression",
                          "original": "someInitiallyTrueProperty",
                          "parts": [
                            "someInitiallyTrueProperty"
                          ],
                          "data": false
                        }
                      ],
                      "hash": {
                        "type": "Hash",
                        "pairs": []
                      }
                    }
                  ],
                  "hash": {
                    "type": "Hash",
                    "pairs": []
                  }
                },
                {
                  "type": "StringLiteral",
                  "value": " ",
                  "original": " "
                },
                {
                  "type": "SubExpression",
                  "path": {
                    "type": "PathExpression",
                    "original": "if",
                    "parts": [
                      "if"
                    ],
                    "data": false
                  },
                  "params": [
                    {
                      "type": "PathExpression",
                      "original": "isBig",
                      "parts": [
                        "isBig"
                      ],
                      "data": false
                    },
                    {
                      "type": "StringLiteral",
                      "value": "big",
                      "original": "big"
                    },
                    {
                      "type": "StringLiteral",
                      "value": "small",
                      "original": "small"
                    }
                  ],
                  "hash": {
                    "type": "Hash",
                    "pairs": []
                  }
                },
                {
                  "type": "StringLiteral",
                  "value": " ",
                  "original": " "
                }
              ],
              "hash": {
                "type": "Hash",
                "pairs": []
              }
            }
          }
        ]
      },
      "escaped": true
    }
  ],
  "blockParams": []
}

This then produces the following spec which looks incorrect (there's nothing about -normalize-class in it):

{
  "statements": [
    [
      "append",
      [
        "helper",
        [
          "foo-bar"
        ],
        null,
        {
          "class": [
            "helper",
            [
              "concat"
            ],
            [
              [
                "helper",
                [
                  "if"
                ],
                [
                  [
                    "get",
                    [
                      "someInitiallyTrueProperty"
                    ]
                  ],
                  [
                    "helper",
                    null,
                    [
                      "someInitiallyTrueProperty",
                      [
                        "get",
                        [
                          "someInitiallyTrueProperty"
                        ]
                      ]
                    ],
                    null
                  ]
                ],
                null
              ],
              " ",
              [
                "helper",
                [
                  "if"
                ],
                [
                  [
                    "get",
                    [
                      "isBig"
                    ]
                  ],
                  "big",
                  "small"
                ],
                null
              ],
              " "
            ],
            null
          ]
        }
      ],
      false
    ]
  ],
  "locals": [],
  "named": [],
  "yields": [],
  "blocks": [],
  "meta": {
    "moduleName": "-top-level"
  }
}

Here are the equivalent htmlbars statements:

statements: [
  ["inline","foo-bar",[],["class",["subexpr","concat",[["subexpr","if",[["get","someInitiallyTrueProperty",[],0,0,0,0],["subexpr","-normalize-class",["someInitiallyTrueProperty",["get","someInitiallyTrueProperty",[],0,0,0,0]],[],[],0,0]],[],[],0,0]," ",["subexpr","if",[["get","isBig",[],0,0,0,0],"big","small"],[],[],0,0]," "],[],[],0,0]],["loc",[null,[1,0],[1,73]]],0,0]
]

[GavinJoyce]

Failing test: #14019
Related PR where the glimmer -normalize-class helper was added: #13724

[GavinJoyce]

@chadhietala perhaps you might be able to add some insight here?

[chadhietala]

Let me take a look 🙇

[GavinJoyce]

This was fixed in #14028.