ExportDeclaration and semicolons/ASI

[mathiasbynens]

https://tc39.github.io/ecma262/#sec-automatic-semicolon-insertion explicitly mentions export statements:

Certain ECMAScript statements ([…] export declarations […]) must be terminated with semicolons. Such semicolons may always appear explicitly in the source text. For convenience, however, such semicolons may be omitted from the source text in certain situations. These situations are described by saying that semicolons are automatically inserted into the source code token stream in those situations.

Furthermore, table 43 (although purely illustrative) includes the semicolons in all of its examples: https://tc39.github.io/ecma262/#table-42

However, the ExportDeclaration grammar doesn’t include the semicolon for the following cases:

• export HoistableDeclaration, e.g. export function foo() {}
• export ClassDeclaration, e.g. export class Bar {}
• export default HoistableDeclaration, e.g. export default function baz() {}
• export default ClassDeclaration, e.g. export default class Qux {}

If the grammar is correct, then:

1. https://tc39.github.io/ecma262/#sec-automatic-semicolon-insertion should probably be changed to exclude export since it’s currently overgeneralizing
2. Table 43 should be changed to omit the semicolon after export default function f(){} and export default function(){}

cc @jmm

[allenwb]

Yes, the grammar is correct.

I suggest rewriting the first sentence of https://tc39.github.io/ecma262/#sec-automatic-semicolon-insertion to be:

Certain ECMAScript statements (empty statement, let, const, import, and >>some<< export declarations...

and yes, remove the two semicolon in Table 43 on the function exports.

[jmm]

@allenwb 👍 That's what the most recent commit in #285 says now (though not that exact wording).