[Transforms] Down-level transformations for Async Functions #9175

rbuckton · 2016-06-15T01:07:21Z

This change adds support for transforming a subset of generator function features to a down-level representation to support async functions when targeting ES5 or ES3.

…mer-es6-generators

…er-es6-generators

…led.

…lines.

rbuckton · 2016-06-16T00:26:15Z

CC: @vladima, @mhegazy, @yuit, @sandersn, @weswigham, @DanielRosenwasser

weswigham · 2016-06-17T05:42:01Z

src/compiler/factory.ts

@@ -139,7 +139,7 @@ namespace ts {
        return node;
    }

-    export function createTempVariable(recordTempVariable: (node: Identifier) => void, location?: TextRange): Identifier {
+    export function createTempVariable(recordTempVariable: ((node: Identifier) => void) | undefined, location?: TextRange): Identifier {


Why not recordTempVariable?: (node: Identifier) => void?

To catch mistakes. Its acceptable to not record the temp variable, but you almost always want to. The only cases where we don't are when we're creating a temp parameter, or we are going to add the temp variable name to a VariableDeclarationList ourselves.

weswigham · 2016-06-17T07:43:39Z

We need to handle directive prologues ("use strict";) when transforming async functions - I looked at the output of the tests/cases/conformance/async/es6/await[Binary,Call]Expression_es6 tests on this branch (which conveniently always have a string as their first statement!) and noticed that we move prologues into the generator function we synthesize - this is likely incorrect (even if it's our current behavior) if the consumer is using custom prologues (if they were just using "use strict" they may never notice). In any case, generators, also, need to special case retaining prologues as the first statement in the original outer function declaration (though, maybe not applicable right now since generators only arise as a consequence of async functions).

Also, would it be possible to just see the results of those same conformance tests running vs es5/es3? I know you added a bunch of new tests, but simply replicating the tests/cases/conformance/async/es6 directory for es5 and maybe es3 would be pertinent with this change. (And allow useful comparisons) #Resolved

weswigham · 2016-06-17T08:19:35Z

I don't think there's any issues, but I couldn't find a test to confirm - I don't see any tests (existing or otherwise) covering constructs such as class extends (await whatever) (which should be valid within an async function). Given we check our emit for await pretty much everywhere else, we should probably add tests in an extends clause.

weswigham · 2016-06-17T09:04:02Z

tests/baselines/reference/exportEqualsAmd.js

@@ -4,6 +4,6 @@ export = { ["hi"]: "there" };
 //// [exportEqualsAmd.js]
 define(["require", "exports"], function (require, exports) {
    "use strict";
-    return (_a = {}, _a["hi"] = "there", _a);
+    return _a = {}, _a["hi"] = "there", _a;


Is the removal of the parenthesis in this test output and the one below intentional? #Resolved

Yes. The node factories will automatically add parenthesis if they are needed. As a result, many places where we explicitly added parentheses now instead leverage this behavior. In this instance, the createReturn factory does not need to parenthesize, so they are not added.

…ity to treat some statements as if they were prologue directives.

…urning global promise, pass this to __generator

…referencing 'arguments' in a generator.

rbuckton · 2016-06-28T01:06:37Z

@yuit, @weswigham: Please take another look following the recent commits.
@mhegazy, @vladima, @DanielRosenwasser: Any comments?

olee · 2016-07-22T20:33:24Z

Does this PR being merged mean we can use async/await now with transpilation to < ES6?

sandersn · 2016-07-22T20:34:52Z

It's merged with the transforms branch, not master. It won't ship until transforms merges into master.

cime · 2016-09-01T13:00:35Z

Anything new on this one? When will it be available in typescript@next?

mhegazy · 2016-09-01T19:10:22Z

should start showing up in typescript@next next week.

nippur72 · 2016-09-18T09:23:34Z

those using tslib and noEmitHelpers must install tslib from github as the npm package is not updated yet (and thus does not contain __generator).

jkobylec · 2016-10-14T23:50:39Z

I got excited enough by @mghegazy's comment earlier that I went ahead and installed typescript@next on my project to start refactoring some of my more labyrinthine promise usage into async/await. And did not bother to check whether transforms had actually been merged into master 😄

And I was like, whoa, this already works when targeting ES5! But then I realized the output is still using ES6 generators, which just happen to work in Chrome and the iOS 10 webview I was testing in 🤐

mhegazy · 2016-10-15T00:34:30Z

And I was like, whoa, this already works when targeting ES5! But then I realized the output is still using ES6 generators, which just happen to work in Chrome and the iOS 10 webview I was testing in

@jkobylec i do not think this is accurate. Emitting async functions for ES3/ES5 is supported in typescript@next.

here is a demonstration.

c:\test>tsc --v
Version 2.1.0-dev.20161014

c:\test>type a.ts
async function test() {
    await bar();
}

c:\test>tsc --target ES5 --lib es5,es2015.promise a.ts
a.ts(2,11): error TS2304: Cannot find name 'bar'.

c:\test>type a.js
var __awaiter =...
var __generator = ...

function test() {
    return __awaiter(this, void 0, void 0, function () {
        return __generator(this, function (_a) {
            switch (_a.label) {
                case 0: return [4 /*yield*/, bar()];
                case 1:
                    _a.sent();
                    return [2 /*return*/];
            }
        });
    });
}

Also i would recommend creating a new issue instead of commenting on a closed PR. thanks.

jkobylec · 2016-10-15T00:56:40Z

My assumption was that the incorporation into master was still in progress
which is why I didn't open a new issue, but seems like the behavior I'm
encountering may be an oddity in my build tool chain I'll need to track
down, then. Apologies if I caused any alarm.
On Fri, Oct 14, 2016 at 5:35 PM Mohamed Hegazy notifications@github.com
wrote:

And I was like, whoa, this already works when targeting ES5! But then I
realized the output is still using ES6 generators, which just happen to
work in Chrome and the iOS 10 webview I was testing in

@jkobylec https://github.com/jkobylec i do not think this is accurate.
Emitting async functions for ES3/ES5 is supported in typescript@next.

here is a demonstration.

c:\test>tsc --v
Version 2.1.0-dev.20161014

c:\test>type a.ts
async function test() {
await bar();
}

c:\test>tsc --target ES5 --lib es5,es2015.promise a.ts
a.ts(2,11): error TS2304: Cannot find name 'bar'.

c:\test>type a.js
var __awaiter =...
var __generator = ...

function test() {
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0: return [4 /yield/, bar()];
case 1:
_a.sent();
return [2 /return/];
}
});
});
}

Also i would recommend creating a new issue instead of commenting on a
closed PR. thanks.

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rbuckton added 15 commits February 29, 2016 11:04

Early support for generators.

d506e92

Merge branch 'transforms-transformer-module' into transforms-transfor…

88b38f8

…mer-es6-generators

Merge branch 'transforms-transformer-module' into transforms-transfor…

aaf3ab7

…mer-es6-generators

Fixed labels

c267691

merge branch 'transforms-fixMoreSourceMaps' into transforms-transform…

83b4cbb

…er-es6-generators

Fix issues after merge

4ae83fa

Merge branch 'transforms' into transforms-generators

e85d3e6

Cleanup, only support generators for async functions, added emit helper.

0948f73

Adds progress indicators to the runtests-parallel build task.

8190666

Fixed typo

3681e3c

Fixes an issue with runtests-parallel when global mocha is not instal…

4afb8c4

…led.

Fixes runtests-parallel not reporting failure for failed tests.

aa4662e

Cleanup, fix linter errors, follow hoisted declarations.

27931d5

Added tests and fixed related emit issues.

ea61f2b

Merge branch 'transforms' into transforms-generators

9073572

rbuckton added the Domain: Transforms Relates to the public transform API label Jun 15, 2016

msftclas added the cla-not-required label Jun 15, 2016

rbuckton added 3 commits June 15, 2016 11:04

Merge branch 'transforms' into transforms-generators

5e31b25

Merge branch 'transforms' into transforms-generators

4eb2a82

Add support for external helpers module, cleanup, and accept new base…

278a350

…lines.

weswigham reviewed Jun 17, 2016
View reviewed changes

rbuckton added 7 commits June 27, 2016 13:48

Move 'use strict' directive out of generator for async function.

393ee28

Added es5 conformance tests for await in binary.

5b2e11c

Added es5 conformance tests for async function declarations. Add abil…

48a9562

…ity to treat some statements as if they were prologue directives.

Added es5 conformance tests for awaiting a call

0c647c3

Added additional es5 conformance tests, better emit for functions ret…

203dab4

…urning global promise, pass this to __generator

Added es5 conformance tests for async arrow functions, add error for …

644e4da

…referencing 'arguments' in a generator.

Additional comments per PR feedback.

9e3d6f8

MattiasBuelens mentioned this pull request Jul 1, 2016

ES6 Generator support #1564

Closed

frederickfogerty mentioned this pull request Jul 17, 2016

Move global DSL type definitions into an index file. philcockfield/ui-harness#93

Closed

rbuckton added 3 commits July 18, 2016 15:43

Merge branch 'transforms' into transforms-generators

252cc25

Accept baselines plus new linter warnings.

c832444

Updated comment

c285767

rbuckton merged commit d4ad7f3 into transforms Jul 20, 2016

rbuckton deleted the transforms-generators branch July 20, 2016 19:12

rbuckton restored the transforms-generators branch July 20, 2016 19:12

weswigham deleted the transforms-generators branch August 11, 2016 01:44

tony19 mentioned this pull request Oct 2, 2016

Add support for http2 Polymer/polyserve#98

Merged

atsu85 referenced this pull request in aurelia/template-lint Oct 9, 2016

feat(rework): new layout

a59b362

DickvdBrink mentioned this pull request Oct 19, 2016

Support async/await in ES5 #5211

Closed

kitsonk mentioned this pull request Nov 15, 2016

Migrate to TypeScript 2.1 dojo/meta#111

Closed

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[Transforms] Down-level transformations for Async Functions #9175

[Transforms] Down-level transformations for Async Functions #9175

rbuckton commented Jun 15, 2016

rbuckton commented Jun 16, 2016

weswigham Jun 17, 2016

rbuckton Jun 17, 2016

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rbuckton Jun 22, 2016

rbuckton commented Jun 28, 2016

olee commented Jul 22, 2016

sandersn commented Jul 22, 2016

cime commented Sep 1, 2016

mhegazy commented Sep 1, 2016

nippur72 commented Sep 18, 2016

jkobylec commented Oct 14, 2016

mhegazy commented Oct 15, 2016

jkobylec commented Oct 15, 2016

[Transforms] Down-level transformations for Async Functions #9175

[Transforms] Down-level transformations for Async Functions #9175

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