Object literal shorthand generator methods have incorrect range

[btmills]

Perhaps this is intentional, but the range given to object literal shorthand generator methods includes only the method body {}. Since they key is part of the parent property and overlapping, non-ancestral ranges might get confusing, I'm not sure that the FunctionExpression's range should include all of *foo(arg1) {}, but it seems like the range should expand to at least (arg1) {}.

Related: eslint/eslint#1677

//test.js
var inspect = require('util').inspect,
    espree = require('espree');

var source = [
    "({",
    "    *foo(arg1) {}",
    "})"
].join("\n");

var ast = espree.parse(source, {
    range: true,
    tokens: true,
    ecmaFeatures: {
        generators: true,
        objectLiteralShorthandMethods: true
    }
});

console.log(inspect(ast.body[0].expression.properties[0]));
console.log(inspect(ast.body[0].expression.properties[0].value.params[0]));
console.log(inspect(ast.tokens));

$  node test.js
{ type: 'Property',
  key: { type: 'Identifier', name: 'foo', range: [ 8, 11 ] },
  value:
   { type: 'FunctionExpression',
     id: null,
     params: [ [Object] ],
     defaults: [],
     body: { type: 'BlockStatement', body: [], range: [Object] },
     rest: null,
     generator: true,
     expression: false,
     range: [ 18, 20 ] },
  kind: 'init',
  method: true,
  shorthand: false,
  computed: false,
  range: [ 7, 20 ] }
{ type: 'Identifier', name: 'arg1', range: [ 12, 16 ] }
[ { type: 'Punctuator', value: '(', range: [ 0, 1 ] },
  { type: 'Punctuator', value: '{', range: [ 1, 2 ] },
  { type: 'Punctuator', value: '*', range: [ 7, 8 ] },
  { type: 'Identifier', value: 'foo', range: [ 8, 11 ] },
  { type: 'Punctuator', value: '(', range: [ 11, 12 ] },
  { type: 'Identifier', value: 'arg1', range: [ 12, 16 ] },
  { type: 'Punctuator', value: ')', range: [ 16, 17 ] },
  { type: 'Punctuator', value: '{', range: [ 18, 19 ] },
  { type: 'Punctuator', value: '}', range: [ 19, 20 ] },
  { type: 'Punctuator', value: '}', range: [ 21, 22 ] },
  { type: 'Punctuator', value: ')', range: [ 22, 23 ] } ]

Edit: Add arg1 to output.

[nzakas]

Interesting point. The conundrum here is that this behavior matches Esprima's, so even if it's the wrong thing, there's a large compatibly issue to consider.

This definitely seems weird, it's just a matter of figuring out of its a bug to fix or not.

[btmills]

Agreed; I wouldn't advocate breaking compatibility unnecessarily. However, I might be able to make the case that this would be a bug in Esprima:

Now that I edited the test script above to output arg1, it shows a strange scenario in which one can traverse, starting at the FunctionExpression (range 18-20), down into a child, arg1 (range 12-16), that lies outside the range of its parent. I can't think of any other instance off the top of my head where that would be the case.

[nzakas]

I think a good case can be made that this is a bug. Would you mind filing an issue with Esprima to start the discussion?

[btmills]

Upon further investigation, this applies to non-generator shorthand methods as well.

Esprima issue: https://code.google.com/p/esprima/issues/detail?id=625

[btmills]

The Esprima issue has been moved to jquery/esprima#1029.