semi reports missing semicolon on export default class

// test.js
export default class {};

// config.json
{
    "env": {
      "es6": true
    },
    "ecmaFeatures": {
      "modules": true
    },
    "rules": {
        "semi": 2
    }
}

$ eslint --reset --no-eslintrc --config config.json test.js

test.js
  2:23  error  Missing semicolon  semi

✖ 1 problem (1 error, 0 warnings)

Looks like similar cases were addressed in #2178 and this one was missed.

[btmills]

Working on this. It’s quite the bear. In the meantime, this is my interpretation of the spec, broken down by the productions of ExportDeclaration:

export * FromClause ;

Semicolon belongs to ExportDeclaration.

export * from 'foo';

export ExportClause FromClause ;

Semicolon belongs to ExportDeclaration.

export { foo } from 'foo';

export ExportClause ;

Semicolon belongs to ExportDeclaration.

export { foo };

export VariableStatement

Semicolon belongs to VariableStatement.

export var foo;

export Declaration

Declaration : HoistableDeclaration

No semicolon.

export function foo () { }
export function* foo () { }

Declaration : ClassDeclaration

No semicolon.

export class Foo () { }

Declaration : LexicalDeclaration

Semicolon belongs to LexicalDeclaration.

export let foo;
export const foo = 42;

export default HoistableDeclaration

No semicolon.

export default function () { }
export default function* foo() { }

export default ClassDeclaration

No semicolon.

export default class { }

export default AssignmentExpression ;

Semicolon belongs to ExportDeclaration.

export default foo || bar;
export default (foo) => foo.bar();
export default foo = 42;
export default foo += 42;

tl;dr:

• ExportAllDeclaration may have a semicolon.
• ExportNamedDeclaration whose declaration is null may have a semicolon.
• ExportNamedDeclaration with a child declaration does not have a semicolon, though its child may.
• ExportDefaultDeclaration may have a semicolon only if its declaration is an expression.

(end tl;dr)

I find this interesting, from ESTree:

interface ExportNamedDeclaration <: Node {
    type: "ExportNamedDeclaration";
    declaration: Declaration | null;
    specifiers: [ ExportSpecifier ];
    source: Literal | null;
}

Note: Having declaration populated with non-empty specifiers or non-null source results in an invalid state.

If declaration and (specifiers, source) are mutually exclusive, why are they the same node?

Edit: ExportDefaultDeclaration may have a semicolon if its child is an expression.

[voithos]

@lo1tuma Ah, you’re right! That’s… unexpected. Thanks!