1340147 - Wrong function name assigned to default export function

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect, P3)

Description

[André Bargull [:anba]]

Test case, m.js:
---
import f from './q.js';

print("NAME: ", f.name);
---

q.js:
---
export default function() { };
---


Expected: Prints "NAME: default"
Actual: Prints "NAME: *default*"


Spec: 
14.1.20 Runtime Semantics: InstantiateFunctionObject
Production |FunctionDeclaration : function(FormalParameters){FunctionBody}|, step 3

https://tc39.github.io/ecma262/#sec-function-definitions-runtime-semantics-instantiatefunctionobject

Comment 1

[André Bargull [:anba]]

Try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e783125a34fa483b6fc10204d5be15699e793c9d

Comment 2

[André Bargull [:anba]]

Attachment: bug1340147.patch

As far as I can tell, it doesn't really matter if the internal binding for default exports is named "*default*" or "default", because both names cannot be used for normal bindings (var, let, const, etc.). That means we can simply switch the name of the internal binding from "*default*" (the name used in the spec) to "default" without breaking anything. And now the existing code to name functions (and classes) just works (TM) and default exported functions and classes will be correctly named "default" instead of "*default*".

Additionally I've fixed another bug which was revealed when I enabled the test262 tests: We didn't implement naming anonymous functions in default export expressions <https://tc39.github.io/ecma262/#sec-exports-runtime-semantics-evaluation>.

Comment 3

[Jon Coppeard (:jonco)]

Comment on attachment 8930043 [details] [diff] [review]
bug1340147.patch

Review of attachment 8930043 [details] [diff] [review]:
-----------------------------------------------------------------

Thank you for the fix, this is great.

Comment 4

[André Bargull [:anba]]

Try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=de0a3a0dc4e40076356c589e23860fa74f1a2e64

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/65d596a31eb9
Correctly name default function exports as "default". r=jonco

Comment 6

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/65d596a31eb9