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ivy: accessing undefined ViewChild properly with elvis operator in template breaks #34087
Description
🐞 bug report
Affected Package
The issue is caused by package @angular/core
Is this a regression?
Yes, works fine in v8
Description
If I add a ViewChild decorator to an undefined component in a template and try and access it using the elvis operator in a template then the expression breaks and nothing is outputted in the template.
🔬 Minimal Reproduction
Where foo is:
https://github.com/mattlewis92/ivy-view-child-accesssor-bug/blob/master/src/app/app.component.ts#L11
🔥 Exception or Error
There is no error, it fails silently to render:
🌍 Your Environment
Angular Version:
Angular CLI: 9.0.0-rc.3
Node: 12.10.0
OS: darwin x64
Angular: 9.0.0-rc.3
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Package Version
-----------------------------------------------------------
@angular-devkit/architect 0.900.0-rc.3
@angular-devkit/build-angular 0.900.0-rc.3
@angular-devkit/build-optimizer 0.900.0-rc.3
@angular-devkit/build-webpack 0.900.0-rc.3
@angular-devkit/core 9.0.0-rc.3
@angular-devkit/schematics 9.0.0-rc.3
@ngtools/webpack 9.0.0-rc.3
@schematics/angular 9.0.0-rc.3
@schematics/update 0.900.0-rc.3
rxjs 6.5.3
typescript 3.6.4
webpack 4.41.2
Anything else relevant?
Nope
Activity
AndrewKushnir commentedon Dec 4, 2019
Hi @mattlewis92, thanks for reporting this issue.
I performed the investigation and found out that the code generated by Ivy Compiler in a
templatefunction looks correct (compiled locally):and it looks like parentheses are removed after further processing (presumably in CLI):
Which changes the logic and makes the code return
null(and render nothing) instead of rendering 'bam' string.@filipesilva do you know if this is an optimization step in CLI that might affect this?
AndrewKushnir commentedon Dec 4, 2019
FYI @alxhub performed further investigation and fixed the problem in PR #34221 👍
The problem was that I looked at the JIT output and the problem was present in AOT output (which is now aligned with JIT).
Thank you.
mattlewis92 commentedon Dec 4, 2019
Amazing, thank you for looking into it so quickly! ❤️
fix(ivy): properly parenthesize ternary expressions when emitted
fix(ivy): properly parenthesize ternary expressions when emitted (#34221
angular-automatic-lock-bot commentedon Jan 6, 2020
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