Ivy ngFor wont over ride variable in scope

[e-davidson]

🐞 bug report

Affected Package

The issue is caused by the new Ivy renderer.

Is this a regression?

Yes, it is working as expected when ivy isn't enabled.

Description

the variable name used for the variable in the ngFor loop can no longer be the same as the variable you're using within the ngFor from the component.

🔬 Minimal Reproduction

using @angular/cli@8.0.0-rc.4 create a new project.
Add a property to the AppComponent someClass: any;

Add the following to the html template of the component.

<div *ngFor='let someClass of someClass.children' >

</div>

enable ivy
run ng build --aot

It doesn't matter the type of someClass. Let it be any.
It appears that ivy can't differentiate between the someClass in let someClass and someClass in someClass.children.

The code won't compile unless you change the name to something different.
Like this.

<div *ngFor='let someClass2 of someClass.children' >

</div>

https://stackblitz.com/edit/angular-eurwqh

I'm not sure how to get stack blitz to run with the --aot flag. So here's a git repo with the same code. https://github.com/e-davidson/angular-ivy-issue

🔥 Exception or Error

ERROR in : Error: Could not resolve [object Object] / undefined
    at Scope.resolve (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:549:23)
    at tcbResolve (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:827:34)
    at C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:755:74
    at astToTypescript (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\expression.js:47:24)
    at astToTypescript (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\expression.js:59:28)
    at Object.astToTypescript (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\expression.js:54:20)
    at tcbExpression (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:755:29)
    at processAttribute (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:802:28)
    at Array.forEach ()
    at tcbGetInputBindingExpressions (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:792:30)
    at TcbDirectiveOp.execute (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:300:28)
    at Scope.executeOp (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:622:26)
    at Scope.render (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:561:22)
    at Object.generateTypeCheckBlock (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_block.js:43:37)
    at TypeCheckFile.addTypeCheckBlock (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\type_check_file.js:47:41)
    at TypeCheckContext.addTemplate (C:\Users\edavidson\src\temp\MatSortUpdateIssue\MatSortUpdateIssue\node_modules\@angular\compiler-cli\src\ngtsc\typecheck\src\context.js:98:36)

🌍 Your Environment

Angular Version:

Angular CLI: 8.0.0-rc.4
Node: 12.3.1
OS: win32 x64
Angular: 8.0.0-rc.5
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.800.0-rc.4
@angular-devkit/build-angular     0.800.0-rc.4
@angular-devkit/build-optimizer   0.800.0-rc.4
@angular-devkit/build-webpack     0.800.0-rc.4
@angular-devkit/core              8.0.0-rc.4
@angular-devkit/schematics        8.0.0-rc.4
@angular/cli                      8.0.0-rc.4
@ngtools/json-schema              1.2.0
@ngtools/webpack                  8.0.0-rc.4
@schematics/angular               8.0.0-rc.4
@schematics/update                0.800.0-rc.4
ng-packagr                        5.2.0
rxjs                              6.5.2
typescript                        3.4.5
webpack                           4.30.0

[Airblader]

I'd say this should throw an error so that developers stop shadowing names.

[JoostK]

This may be fixed by #30669

[kara]

@e-davidson Could you try again with the next release (8.1.0-beta.0)? It should have the fix in #30669

[e-davidson]

@kara
I tried it and it is fixed.
Then you.

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