"Cannot resolve symbol al" after `else if (! (l instanceof ArrayList al))`

[Jean-Noël Rouvignac]

Hello folks,

JDK 25 rampdown phase 1 is now behind us, congrats and thanks for all the
work done to get there!

I am reviving this use case to see if anyone agrees that this may be a bug?

Thank you,
Jean-Noel


On Wed, Apr 16, 2025 at 11:37 AM Jean-Noël Rouvignac <
jean-noel.rouvignac at pingidentity.com> wrote:

> Hello amber-dev folks!
>
> While using pattern matching for instanceof I noticed a small incoherent
> oddity.
>
> Take this code:
> ```
> static void ensureCapacity(List l) {
>   if (l instanceof LinkedList) {
>     throw new IllegalArgumentException("Use an efficient list
> implementation");
>   } else if (!(l instanceof ArrayList al)) {
>     return;
>   }
>   al.ensureCapacity(10);
>   System.out.println("done");
> }
>
> ensureCapacity(new ArrayList());
> ```
>
> The compiler rejects this code with: `Cannot resolve symbol 'al'`.
> (I have tested that code with JDK 24 in the playground (
> https://dev.java/playground) but also in my IDE with JDK 21)
>
> However #1, removing the `else` keyword makes the code successfully
> compile:
> ```
>   }
>   if (!(l instanceof ArrayList al)) {
>     return;
>   }
> ```
>
> However #2, adding an additional `else` keyword makes the code
> successfully compile:
> ```
>         } else if (!(l instanceof ArrayList al)) {
>             return;
>         } else {
>             al.ensureCapacity(10);
>             System.out.println("done");
>         }
> ```
>
> While option #1 and #2 are acceptable workarounds, it looks to me like
> there could be a bug in javac? Therefore I am bringing this to your
> attention so you can decide if it is a bug or not.
>
> I searched the JDK's bug tracker for this specific case, but could not
> find anything related.
>
> Thanks!
> Jean-Noël
>


-- 
<https://www.pingidentity.com/> <https://www.pingidentity.com/>[image: Ping
Identity] <https://www.pingidentity.com/>
Jean-Noel Rouvignac
Senior Principal Software Engineer
jean-noel.rouvignac at pingidentity.com

<https://www.pingidentity.com/en/events/youniverse.html>
<https://www.pingidentity.com/en/events/youniverse.html>
<https://www.pingidentity.com/en/events/youniverse.html>
<https://www.pingidentity.com/en/gartner-magic-quadrant-access-management.html?utm_medium=email>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/virtualsummit.html?utm_source=sales&utm_medium=email&utm_campaign=VFE-GLOBAL-2025.03.18-19-PingVirtualEvent>
<https://www.pingidentity.com/en/events/youniverse.html>
Connect with us: [image: Glassdoor logo]
<https://www.glassdoor.com/Overview/Working-at-Ping-Identity-EI_IE380907.11,24.htm>[image:
LinkedIn logo] <https://www.linkedin.com/company/21870>[image: Twitter logo]
<https://twitter.com/pingidentity>[image: YouTube logo]
<https://www.youtube.com/user/PingIdentityTV>[image: Blog logo]
<https://www.pingidentity.com/en/blog.html>
To view our privacy policy, click here
<https://www.pingidentity.com/en/legal/privacy.html>
To stop receiving these emails, click here
<https://4.pingidentity.com/PreferenceCenter.html>

-- 
_CONFIDENTIALITY NOTICE: This email may contain confidential and privileged 
material for the sole use of the intended recipient(s). Any review, use, 
distribution or disclosure by others is strictly prohibited.  If you have 
received this communication in error, please notify the sender immediately 
by e-mail and delete the message and any file attachments from your 
computer. Thank you._
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/amber-dev/attachments/20250607/93b32a14/attachment-0001.htm>