1219028 - Remove use of non-standard Function.prototype.isGenerator from devtools/.

Status: RESOLVED FIXED

(DevTools :: General, defect)

Description

[Tooru Fujisawa [:arai]]

https://hg.mozilla.org/mozilla-central/file/3af8b8e56340/devtools/shared/DevToolsUtils.js#l814

> exports.isGenerator = function (fn) {
>   return typeof fn === "function" && fn.isGenerator();
> };

Function.prototype.isGenerator is non-standard and we're going to remove it (bug 1119777).
looks like only ES6 generator is used there, so it could be written as following if fn always comes from same global.

> let GeneratorFunction = Object.getPrototypeOf(function*(){}).constructor;
> exports.isGenerator = function (fn) {
>   return fn instanceof GeneratorFunction;
> };

if fn may come from different global, following will be the alternative.

> exports.isGenerator = function (fn) {
>   if (typeof fn !== "function") {
>     return false;
>   }
>   let proto = Object.getPrototypeOf(fn);
>   if (!proto) {
>     return false;
>   }
>   let ctor = proto.constructor;
>   if (!ctor) {
>     return false;
>   }
>   return ctor.name == "GeneratorFunction";
> };

Comment 1

[Tooru Fujisawa [:arai]]

can legacy generator be passed to isGenerator function?
if yes and they're all in-tree things, we should fix it too.
if yes and they can be user input or something, we should fix everything at once when dropping legacy generator support.
if no, we can just apply one of the fix in comment #0 :)

Comment 2

[Nick Fitzgerald [:fitzgen] [⏰PST; UTC-8]]

(In reply to Tooru Fujisawa [:arai] from comment #1)
> can legacy generator be passed to isGenerator function?
> if yes and they're all in-tree things, we should fix it too.
> if yes and they can be user input or something, we should fix everything at
> once when dropping legacy generator support.
> if no, we can just apply one of the fix in comment #0 :)

We can ignore legacy generators, but must handler generators from other globals. r=me on the second implementation in comment 0. Thanks!

Comment 3

[Tooru Fujisawa [:arai]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/bda42988725cb4ed31f56abc9ff7717d91adf64a
Bug 1219028 - Remove use of non-standard Function.prototype.isGenerator from devtools/. r=fitzgen

Comment 4

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/bda42988725c