Compiler error message not clear for Valhalla EA 2

[Remi Forax]

> From: "Remi Forax" <forax at univ-mlv.fr>
> To: "David Alayachew" <davidalayachew at gmail.com>
> Cc: "valhalla-dev" <valhalla-dev at openjdk.org>
> Sent: Wednesday, October 29, 2025 9:30:22 AM
> Subject: Re: Compiler error message not clear for Valhalla EA 2

> This is an interesting case because i'm not sure the compiler should emit an
> error here.

> Currently the error occurs because as you said the call to super() is added
> after the call to throw.

> But throwing an exception in a constructor of an identity class is valid, and i
> do not see a reason why this behavior should not be the same in the case of a
> value class.

or perhaps javac should behave more like when there is an explicit call to 'return' 

value class V { 
V ( int v ) { 
return ; 
} 
} 

java: 'return' not allowed before explicit constructor invocation 

> regards,
> Rémi

regards, 
Rémi 

>> From: "David Alayachew" <davidalayachew at gmail.com>
>> To: "valhalla-dev" <valhalla-dev at openjdk.org>
>> Sent: Wednesday, October 29, 2025 5:30:23 AM
>> Subject: Re: Compiler error message not clear for Valhalla EA 2

>> The compiler error message goes away if I put a super(); as the first statement
>> in the constructor. But still, that error message could be clearer.

>> From: "David Alayachew" <davidalayachew at gmail.com>
>> To: "valhalla-dev" <valhalla-dev at openjdk.org>
>> Sent: Wednesday, October 29, 2025 5:27:55 AM
>> Subject: Compiler error message not clear for Valhalla EA 2

>> Hello [ mailto:valhalla-dev at openjdk.org | @valhalla-dev ] ,

>> While testing out the new Valhalla EA that came out a few days ago, I ran into
>> the following compiler error.

>> Here is a minified example.

>> public value class abc
>> {

>> public abc()
>> {
>> throw new UnsupportedOperationException();
>> }

>> public static void someHelperMethod()
>> {}

>> }

>> And here is the compiler error message.

>> $ java --enable-preview abc.java
>> abc.java:5: error: unreachable statement
>> {
>> ^
>> 1 error
>> error: compilation failed

>> That location is the opening curly brace of the constructor.

>> Can we have a more clear error message?

>> Thank you for your time and consideration.
>> David Alayachew
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/valhalla-dev/attachments/20251029/5f300c13/attachment-0001.htm>