Member expression on number literal generates wrong output

[Gozala]

require("escodegen").generate({
            "type": "ExpressionStatement",
            "expression": {
                "type": "MemberExpression",
                "computed": false,
                "object": {
                    "type": "Literal",
                    "value": 4,
                    "raw": "4"
                },
                "property": {
                    "type": "Identifier",
                    "name": "foo"
                }
            }
        })
// => '4..foo;'

While it should output:

(4).foo;

[Gozala]

P.S.: I'm using version: '0.0.23'

[Constellation]

Thx for filing issue. But this is completely valid ECMAScript.
First dot is floating point and second dot is property lookup.
So you can also write as follows,

4.                .  foo;

You can check it in your JS engine OR http://esprima.org/demo/parse.html?code=4..foo

[Constellation]

Of cource, 4.foo; is syntax invalid :)

[Gozala]

Oh wow I have not realized that :) Thanks

[dannycochran]

@Constellation but why does it coerce it to 4..foo?

If you translate 4..foo back to an AST, the "raw" value of the Literal type is "4.", but the AST provided by @Gozala doesn't have that dot following the 4. It seems like the AST should actually be considered invalid, no?

[michaelficarra]

@dannycochran If the Literal AST node has a raw value (and it is lexically valid), it will be used. So the round-trip property still holds.

[dannycochran]

@michaelficarra but the AST changes roundtrip, no?

[michaelficarra]

Ah, I think I see what you mean. Thanks, @dannycochran. The fix here would be to compile to

4 .foo;

[dannycochran]

@michaelficarra -- I think that seems right, though I could also see the case for escodegen to throw an error and say an AST like the one provided by @Gozala is invalid.

it seems like ESTree should have a separate way of represeting 4 .foo and (4).foo, as it does for 4..foo

[michaelficarra]

@dannycochran I disagree. Those should be identical in an AST. The fact that they're not due to raw on Literal is the problem.