fix: add generic info for methods with thisArg of built-in classes by e-cloud · Pull Request #12784 · microsoft/TypeScript

Scott (e-cloud) · 2016-12-09T03:47:41Z

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Note: need guide to write tests

Microsoft Contribution License Agreements (msftclas) · 2016-12-09T03:47:46Z

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Scott (e-cloud) · 2016-12-09T03:48:57Z

Daniel Rosenwasser (@DanielRosenwasser) Mohamed Hegazy (@mhegazy) can you have a review and give some guide on how to write corresponding tests?

Microsoft GitHub User (msftgits) · 2016-12-09T17:14:54Z

Hi, I am closing and re-opening this PR to bump the CLA bot. Sorry for the inconvenience!

Microsoft Contribution License Agreements (msftclas) · 2016-12-09T17:14:59Z

Hi Scott (@e-cloud), I'm your friendly neighborhood Microsoft Pull Request Bot (You can call me MSBOT). Thanks for your contribution!
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Scott (e-cloud) · 2016-12-15T02:06:51Z

Mohamed Hegazy (@mhegazy) can you take a review?

Nathan Shively-Sanders (sandersn) · 2016-12-16T18:14:01Z

The change looks good. To write tests, add a file named something like thisTypeInLib.ts in the directory tests/cases/compiler. In the file, put code from the bug you reported in #12548.

Run gulp runtests-parallel then look in tests/baselines/local to make sure that no .errors.txt file exists and also that the .types file is correct. Then run gulp baseline-accept to put the baselines in the reference directory, ready to commit.

After you get that workflow going, you should add tests for all the functions you improved too.
These instructions are explained better in CONTRIBUTING.md; I'm just summarising from memory.

Scott (e-cloud) · 2016-12-17T11:23:51Z

Nathan Shively-Sanders (@sandersn), new test is added. And i find out the new version of tslint breaks down the linting task.

Nathan Shively-Sanders (sandersn) · 2016-12-21T23:42:07Z

+        options.every(function (val, index) {
+            return val === this.options[index];
+        }, this);
+    }


could you also add tests for ReadonlyArray and the other U?.*Array types?

Nathan Shively-Sanders (sandersn) · 2016-12-21T23:43:39Z

+    }
+
+    test(options: string[]) {
+        options.some(function (val, index) {


can you also add tests for find, findIndex, forEach, map?

I'm afraid that it would be problem. As the default compile target seems to be es5. Then it prompts that find not exist in xxx[]. Should we create a test project for it?

You can change the target with a line at the beginning: // @target: es6

your guidance is helpful

Nathan Shively-Sanders (sandersn)

Can you add tests for the other array methods and array types?

Mohamed Hegazy (mhegazy) · 2016-12-22T00:50:55Z

should not this be two overloads:

find(predicate: (this: undefined, value: T, index: number, obj: Array<T>) => boolean): T | undefined;
find<U>(predicate: (this: U, value: T, index: number, obj: Array<T>) => boolean, thisArg : U): T | undefined;

the spec seems to indicate that, here is what MDN has to say: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find

Mohamed Hegazy (mhegazy) · 2016-12-22T00:51:22Z

Also there are other find functions for TypedArrays that should be updated as well.. e.g. Int32Array

Scott (e-cloud) · 2016-12-22T01:29:25Z

Mohamed Hegazy (@mhegazy) what do you mean by:

should not this be two overloads:
find(predicate: (this: undefined, value: T, index: number, obj: Array<T>) => boolean): T | undefined;
find<U>(predicate: (this: U, value: T, index: number, obj: Array<T>) => boolean, thisArg : U): T | >undefined; 
the spec seems to indicate that, here is what MDN has to say: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find

Can you describe it more clearly?

Mohamed Hegazy (mhegazy) · 2016-12-22T18:15:18Z

From MDN:

If a thisArg parameter is provided to find, it will be used as the this for each invocation of the callback. If it is not provided, then undefined is used.

if this is not defined on a function it is inferred to be any. but the behavior at runtime is that if thisArg is not specified as parameter, the this for the callback is undefined.

Scott (e-cloud) · 2016-12-24T10:03:59Z

Mohamed Hegazy (@mhegazy) I see what you mean now.

I have some tries and find out some problems.

TL;DR

Use the forEach of Array<T> in the testfile as example.
with the test code:

class A {
    options: string[];

    addOptions(options: string[]) {
        if (!this.options) {
            this.options = [];
        }
        options.forEach(function (item) {
            this.options.push(item);
        }, this);
        return this;
    }

    testUndefined(options: string[]) {
        options.forEach(function (item) {
            this.options.push(item);
        }); // case1
        options.forEach(function (item) {
            this.options.push(item);
        }, undefined); // case2
        options.forEach(function (item) {
            this.options.push(item);
        }, null); // case3
    }
}

in lib/es5.d.ts

version 1

forEach(callbackfn: (this: undefined, value: T, index: number, array: T[]) => void): void;
forEach<Z>(callbackfn: (this: Z, value: T, index: number, array: T[]) => void, thisArg: Z): void;

erros from thisTypeInNativeThisAssignableMethods.errors.txt:

        testUndefined(options: string[]) {
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'undefined'.
            }); // case1
            options.forEach(function (item) {
                this.options.push(item);
            }, undefined); // case2
            options.forEach(function (item) {
                this.options.push(item);
            }, null); // case3
        }

only case1 will be recognized as error, others are legal rather than error.

version 2

    forEach(callbackfn: (this: undefined, value: T, index: number, array: T[]) => void): void;
    forEach(callbackfn: (this: undefined, value: T, index: number, array: T[]) => void, thisArg: undefined): void;
    forEach<Z>(callbackfn: (this: Z, value: T, index: number, array: T[]) => void, thisArg: Z): void;

erros from thisTypeInNativeThisAssignableMethods.errors.txt:

        testUndefined(options: string[]) {
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'undefined'.
            }); // case1
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'undefined'.
            }, undefined); // case2
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'undefined'.
            }, null); // case3
        }

now all are recognized as undefined, even case3's this should be null.

version 3

    forEach(callbackfn: (this: undefined, value: T, index: number, array: T[]) => void): void;
    forEach(callbackfn: (this: null, value: T, index: number, array: T[]) => void, thisArg: null): void;
    forEach(callbackfn: (this: undefined, value: T, index: number, array: T[]) => void, thisArg: undefined): void;
    forEach<Z>(callbackfn: (this: Z, value: T, index: number, array: T[]) => void, thisArg: Z): void;

erros from thisTypeInNativeThisAssignableMethods.errors.txt:

        testUndefined(options: string[]) {
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'undefined'.
            }); // case1
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'null'.
            }, undefined); // case2
            options.forEach(function (item) {
                this.options.push(item);
                     ~~~~~~~
!!! error TS2339: Property 'options' does not exist on type 'null'.
            }, null); // case3
        }

It seems the nulled-this interface takes precedence. And if the undefined version is placed before null version, the errors are same as version 2

In short

undefined and null is recognized as same. And when undefined is assigned as generic type, it's inferred as any.

Personally, I'm ok with version 2 for temporary solution. Mohamed Hegazy (@mhegazy) do you agree to make three interfaces for all involved methods?

Scott (e-cloud) · 2016-12-24T12:43:44Z

Another thing worths mentioning is that the from static method of all array constructor. They should support iterable parameter and the generic info of Array like is not proper. I just find it accidentally just because from's mapfn also supports thisArg.

Scott (e-cloud) · 2017-01-05T03:15:14Z

Mohamed Hegazy (@mhegazy) Nathan Shively-Sanders (@sandersn) I've rewrite the PR to accomplish the solution commented above.

Note: I use several regexps to globally update the interfaces. Manually updating per interface would be nightmare.

Nathan Shively-Sanders (sandersn) · 2017-01-05T18:00:34Z

Note that option 1 works correctly with // strictNullChecks: true. However, option 2 is OK with me since it provides better errors with strict null checks off. Mohamed Hegazy (@mhegazy), are you OK with this solution as well?

Scott (e-cloud) · 2017-01-06T14:55:50Z

Nathan Shively-Sanders (@sandersn) It seems to fail many tests. Should I update the other baseline files? It would be a lot of files.

Nathan Shively-Sanders (sandersn) · 2017-01-10T17:09:11Z

Yes, the baseline changes are expected: when you add overloads, it changes the symbols and types to reflect those additional overloads, even if the types resulting from the call doesn't change.

Scott (e-cloud) · 2017-01-11T02:12:56Z

Mohamed Hegazy (@mhegazy) Nathan Shively-Sanders (@sandersn) hey, guys. All checks have passed now. How about have a review again?

Scott (e-cloud) · 2017-01-24T08:00:07Z

Mohamed Hegazy (@mhegazy) request for review

Ali Taheri Moghaddar (alitaheri) · 2017-01-24T11:16:51Z

You have a yarn.lock file checked in. Should it be there?

Scott (e-cloud) · 2017-01-24T11:27:33Z

Yes, accident. 😭

when enabling `noImplicitThis`, if assing this argument for methods like `array.forEach` will cause compilation error. This commit fixes it. fix microsoft#12548

Scott (e-cloud) · 2017-03-09T08:39:47Z

Nathan Shively-Sanders (@sandersn) ，I've rebased on master just now. Can you guys give some review and feedback? Coz it's been a while since starting the PR.

The tests failed because of the latest problematic @types/node module. The tests passed locally when i switch @types/node to v6.x.

Mohamed Hegazy (mhegazy) · 2017-03-09T17:24:25Z

I have a fix in master now for the build break. can you give it another try.

Scott (e-cloud) · 2017-03-10T01:31:09Z

tests pass now.

Nathan Shively-Sanders (sandersn) · 2017-03-10T17:17:36Z

Thanks Scott (@e-cloud)!

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Scott (e-cloud) force-pushed the fix/generic-this-arg branch 2 times, most recently from 4339c9a to c42a029 Compare December 17, 2016 11:22

Nathan Shively-Sanders (sandersn) reviewed Dec 21, 2016

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Nathan Shively-Sanders (sandersn) requested changes Dec 21, 2016

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Scott (e-cloud) force-pushed the fix/generic-this-arg branch from c42a029 to 6872883 Compare January 5, 2017 03:10

Scott (e-cloud) force-pushed the fix/generic-this-arg branch from b046380 to b6998a4 Compare January 11, 2017 01:24

Scott (e-cloud) force-pushed the fix/generic-this-arg branch from b6998a4 to 4756b6a Compare January 22, 2017 12:00

Scott (e-cloud) force-pushed the fix/generic-this-arg branch from 4756b6a to 222b828 Compare January 24, 2017 12:05

Scott (e-cloud) force-pushed the fix/generic-this-arg branch from 222b828 to 5c26e62 Compare February 8, 2017 12:17

Scott (e-cloud) added 3 commits March 9, 2017 11:52

fix: add generic info for methods with thisArg of built-in classes

cedad97

when enabling `noImplicitThis`, if assing this argument for methods like `array.forEach` will cause compilation error. This commit fixes it. fix microsoft#12548

test: add tests for this type in native-this-assignable methods

18154fe

test: adjust test case completionEntryForUnionMethod

5f5aa20

Scott (e-cloud) force-pushed the fix/generic-this-arg branch from 5c26e62 to 1b7c11a Compare March 9, 2017 05:52

Mohamed Hegazy (mhegazy) approved these changes Mar 9, 2017

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Nathan Shively-Sanders (sandersn) approved these changes Mar 9, 2017

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test(baseline): update references affected

09fcf5b

Scott (e-cloud) force-pushed the fix/generic-this-arg branch from 1b7c11a to 09fcf5b Compare March 10, 2017 01:16

Nathan Shively-Sanders (sandersn) merged commit bdb6a8a into microsoft:master Mar 10, 2017

Mohamed Hegazy (mhegazy) mentioned this pull request May 23, 2017

Fix Array interface (#10886) #11294

Closed

Mohamed Hegazy (mhegazy) mentioned this pull request Jun 4, 2017

Array cleanup #16223

Merged

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