Type inference bug with method references in OpenJDK 16+ discovered

[Michael Mirwaldt]

Hi Guoxiong,
thanks for trying out my example project, reproducing the bug even under
linux and creating a bug ticket for that.
I hope, my example project helps you to find out what goes wrong with
type inference here and fix that bug.
Best regards,
Michael Mirwaldt

Am 22.06.2021 um 12:04 schrieb Guoxiong Li:
> Hi Michael,
>
> Thanks for reporting this bug.
>
> I reproduced this bug on linux by using the following commands
> and the error messages are similar to yours.
>
> ```
> java -m jdk.compiler/com.sun.tools.javac.Main $(find src/main/java
> -name "*.java")
> java -classpath src/main/java net.mirwaldt.bug.Main
> ```
>
> And I also reproduced it by using the maven to compile.(also on linux)
>
> ```
> mvn clean compile
> java -classpath target/classes/ net.mirwaldt.bug.Main
> ```
>
> It seems that you misuse some commands.
>
> Anyway, it is a reproduced bug.
> Filed https://bugs.openjdk.java.net/browse/JDK-8269121
> <https://bugs.openjdk.java.net/browse/JDK-8269121> in the JBS.
>
> Best Regards,
> -- Guoxiong
>
>
> On Mon, Jun 21, 2021 at 5:49 AM Michael Mirwaldt
> <michael.mirwaldt at gmx.de <mailto:michael.mirwaldt at gmx.de>> wrote:
>
>     Hi,
>     I wanted to report a bug in the type inference with references in
>     OpenJDK 16 and 17-ea.
>     I have created a sample project on
>     https://github.com/mmirwaldt/TypeInferenceBugOfMethodReferences/
>     <https://github.com/mmirwaldt/TypeInferenceBugOfMethodReferences/>
>     <https://github.com/mmirwaldt/TypeInferenceBugOfMethodReferences/
>     <https://github.com/mmirwaldt/TypeInferenceBugOfMethodReferences/>>
>     to reproduce the bug. Just run Main and notice the exception.
>     However, a friend told me that the bug only occurs with compiling
>     directly by javac but not by maven compile.
>     We don't know why. Moreover, it seems to be dependent on the operating
>     system:
>     I haven't been able to reproduce the bug on linux (CentOS 7, OpenJDK
>     16.0.1) yet. Windows 10 and Mac show that bug, though.
>     Can you please have a look on it, try it out and help me creating
>     a bug
>     ticket if you can confirm it's a bug?
>     I mean it must be a bug if the type inference somehow infers the wrong
>     type of a method reference which leads to an exception at runtime,
>     doesn't it?
>     Type inference should either infer the right type or cause a compiler
>     error if it cannot infer the type or isn't sure about it in order
>     to ask
>     the developer for an explicit declaration. Is that right?
>     I am sorry I cannot help you finding the bug in the code of the
>     compiler
>     which infers types. I would if I could.
>     All the best,
>     Michael Mirwaldt
>
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