you mean in case of naming conflicts?

yes, for this case it matters

but if there's no naming conflict it does not

here is an example of failure:        
       '@public' => '@app/public',
       '@runtime' => '@root/runtime',
       '@bower' => '@vendor/bower-asset',
       '@npm' => '@root/node_modules',
       '@web' => '/assets',
       '@app' => 'D:\\git-local\\yiisoft\\app',

umm.... would that cause a failure?

public depend the app

and app its define after

app no exist for @public

Order doesn't matter

application fails

Hmmmm

Build

[Mon Jun  1 14:31:22 2020] PHP Fatal error:  Uncaught InvalidArgumentException: Invalid path alias: @app/public in D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php:141
Stack trace:
#0 D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php(70): Yiisoft\Aliases\Aliases->get('@app/public')
#1 D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php(18): Yiisoft\Aliases\Aliases->set('@public', '@app/public')
#2 D:\git-local\yiisoft\app\vendor\yiisoft\factory\src\Definitions\ArrayBuilder.php(35): Yiisoft\Aliases\Aliases->__construct(Array)
#3 D:\git-local\yiisoft\app\vendor\yiisoft\factory\src\Definitions\ArrayDefinition.php(71): Yiisoft\Factory\Definitions\ArrayBuilder->build(Object(Yiisoft\Di\Container), Object(Yiisoft\Factor
y\Definitions\ArrayDefinition))
#4 D:\git-local\yiisoft\app\vendor\yiisoft\di\src\Container.php(214): Yiisoft\Factory\Definitions\ArrayDefinition->resolve(Object(Yiisoft\Di\Container))
#5 D:\git-local\yiisoft\app\vendor\yiisoft\di\src\Container.php(155): Yiisoft\Di\Container->buildInternal('Yiisoft\\Alias in D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php on
line 141
[Mon Jun  1 14:31:22 2020] 127.0.0.1:59744 [500]: GET / - Uncaught InvalidArgumentException: Invalid path alias: @app/public in D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php
:141
Stack trace:
#0 D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php(70): Yiisoft\Aliases\Aliases->get('@app/public')
#1 D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php(18): Yiisoft\Aliases\Aliases->set('@public', '@app/public')
#2 D:\git-local\yiisoft\app\vendor\yiisoft\factory\src\Definitions\ArrayBuilder.php(35): Yiisoft\Aliases\Aliases->__construct(Array)
#3 D:\git-local\yiisoft\app\vendor\yiisoft\factory\src\Definitions\ArrayDefinition.php(71): Yiisoft\Factory\Definitions\ArrayBuilder->build(Object(Yiisoft\Di\Container), Object(Yiisoft\Factor
y\Definitions\ArrayDefinition))
#4 D:\git-local\yiisoft\app\vendor\yiisoft\di\src\Container.php(214): Yiisoft\Factory\Definitions\ArrayDefinition->resolve(Object(Yiisoft\Di\Container))
#5 D:\git-local\yiisoft\app\vendor\yiisoft\di\src\Container.php(155): Yiisoft\Di\Container->buildInternal('Yiisoft\\Alias in D:\git-local\yiisoft\app\vendor\yiisoft\aliases\src\Aliases.php on
line 141
[Mon Jun  1 14:31:22 2020] 127.0.0.1:59744 Closing
[Mon Jun  1 14:31:22 2020] 127.0.0.1:59748 Accepted

writing a unit test for alias...

Try dd($container->get(\Yiisoft\Aliases\Aliases::class));

in commons work fine.

yep, it doesn't work like that

weird