Use returned values from super calls as 'this' #10762

DanielRosenwasser · 2016-09-07T22:01:55Z

This PR fixes #7574.

In ES2015, constructors which return a value (which is an object) implicitly substitute the value of this for any callers of super(). As a result, it is necessary to capture any potential return value of super() and replace it with this.

Some remaining work might be to do some refactoring on the emit code.

I'd suggest reading one commit at a time.

…ing 'super(...)'.

…r of a derived class.

…in constructors.

…eserved. This came up when a `super()` call was nested in another constructor body. Current logic in the transform says that if the last containing non-arrow function body is non-static, and the current parent isn't a call expression, the call target of a `super` call will become `_super.prototype` instead of `super`. If the state is not saved, the containing arrow function and parent are not saved, and the information for this check won't be accurate.

…class.

andreawyss · 2016-09-15T17:57:59Z

Awesome work!
I have verified, that with this branch of TypeScript, I can now in fact create CustomElements entirely in TypeScript. Thank You
FYI: @treshugart

…SuperCalls

… generated 'super()' calls.

DanielRosenwasser · 2016-09-27T21:52:27Z

I don't think our test harness gives an error for this right now.

@sandersn how have we been operating like this? In any case, it looks like GitHub just has a limitation and might not be showing that file. I seem to have it locally.

sandersn · 2016-09-27T22:01:33Z

It's only been since we made the tests run faster by not writing output for passing tests.

I have the PR open in codeflow too or I would not have noticed the missing file at all. But maybe it's missing at the API level, not just the UI level.

DanielRosenwasser · 2016-09-28T03:55:53Z

@sandersn are you sure you don't see a tests/cases/compiler/derivedClassConstructorWithExplicitReturns01.ts?

sandersn · 2016-09-28T15:50:22Z

When I check out the branch myself I see it, but I don't find it in the github list of files either. I guess it's a limitation of github proper, not just its UI.

rbuckton · 2016-09-30T00:12:02Z

@DanielRosenwasser after the removal of useCapturedThis did you see any changes in the test results?

…SuperCalls

DanielRosenwasser · 2016-09-30T03:35:04Z

@rbuckton nope, no changes.

DanielRosenwasser · 2016-09-30T07:08:59Z

Thanks @sandersn!

DanielRosenwasser added 21 commits September 1, 2016 18:15

Emit '_this' declaration for derived classes; initialize it when call…

9dbab97

…ing 'super(...)'.

Accepted baselines.

99f1df4

Transform other instances of 'this' to '_this' when in the constructo…

d778e78

…r of a derived class.

Accepted baselines for all tests apart from one with source map changes.

c21cc24

Accepted baselines for sourcemap test.

9c6e148

Always tack on a return statement for '_this' in derived classes.

cd5e76b

Accepted baselines.

30ec599

Ensure prologue directives occur first.

bab6d6f

Accepted baselines.

ce953ce

Consolidate '_this' declaration and assignments for first statements …

d6e548b

…in constructors.

Accepted baselines.

d8846dd

Always perform this captures after default & rest parameters.

86088d0

Accepted baselines.

dd27139

Added a test for branched returns at the end of a constructor.

f3dcaae

Accepted baselines.

1be4cee

Don't emit a return statement at the end in most useful cases.

c87a773

Accepted baselines.

d144665

Added test for '_this'.

b476815

Accepted baselines.

230737f

Mark constructors as this-capturing if they are defined in a derived …

b11db57

…class.

msftclas added the cla-not-required label Sep 7, 2016

DanielRosenwasser added 3 commits September 7, 2016 15:42

Merge branch 'master' into useReturnedThisFromSuperCalls

25f9555

Accepted baselines.

3a5fb0c

Added missing semicolons.

f11c646

DanielRosenwasser mentioned this pull request Sep 9, 2016

Design Meeting Notes, 9/9/2016 #10826

Closed

andreawyss mentioned this pull request Sep 15, 2016

Allows to pass to reactify the tagName instead of the CustomElement webcomponents/react-integration#38

Closed

DanielRosenwasser added 2 commits September 19, 2016 17:47

Merge remote-tracking branch 'origin/master' into useReturnedThisFrom…

a63a0d8

…SuperCalls

Accepted baselines.

138e18c

DanielRosenwasser added 7 commits September 27, 2016 11:44

Remove usage of 'useCapturedThis'.

4a5830d

Collapse 'super()' capture/returns into a single return statement for…

c668644

… generated 'super()' calls.

Accepted baselines.

1fbdb86

Restore arrow function.

e0c35f2

Reuse the 'captureThisForNode' function.

f8fbc22

Removed pointlessish overloads.

fb4b503

Moved code around, fixed indent, reworded comment.

b5a1031

DanielRosenwasser force-pushed the useReturnedThisFromSuperCalls branch from 36a5c42 to b5a1031 Compare September 27, 2016 21:45

Consolidated 'super()' transformation logic into one function.

c29ec6f

Merge remote-tracking branch 'origin/master' into useReturnedThisFrom…

02b9917

…SuperCalls

rbuckton approved these changes Sep 30, 2016

View reviewed changes

DanielRosenwasser merged commit bcdf1dc into master Sep 30, 2016

DanielRosenwasser deleted the useReturnedThisFromSuperCalls branch September 30, 2016 07:08

HerringtonDarkholme mentioned this pull request Nov 10, 2016

Incorrect transpiled constructor of derived classes #12123

Closed

DanielRosenwasser mentioned this pull request Nov 23, 2016

#931 - Use Flow for Development skatejs/skatejs#931

Closed

KiaraGrouwstra mentioned this pull request Nov 30, 2016

Add typescript supports fantasyland/fantasy-land#140

Closed

mhegazy added the Breaking Change Would introduce errors in existing code label Dec 2, 2016

mhegazy added this to the TypeScript 2.1 milestone Dec 2, 2016

vvakame mentioned this pull request Mar 17, 2017

Subclass extends Error is broken #14702

Closed

RyanCavanaugh mentioned this pull request Mar 27, 2017

a custom class extends to Object, invoke a member function will produce an error!!! #14869

Closed

DanielRosenwasser mentioned this pull request Sep 19, 2017

Runtime error when mixing into Object with es5 target #18564

Closed

bryanrsmith mentioned this pull request Feb 9, 2018

Unexpected super() return value when subclassing ES5 ctor function chakra-core/ChakraCore#4663

Closed

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Use returned values from super calls as 'this' #10762

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