KT-22210 Use meaningful parameter names instead of p0

[sdeleuze]

In IntelliJ IDEA, when you enable the option that displays implicit parameter names, you get weird p0 parameters in id() and plugin(). Meaningful parameter names would be better.

[JLLeitschuh]

Is this because gradle is compiled without the -parameters compiler flag? This sounds like something that needs to be fixed in the core gradle repository.

https://docs.oracle.com/javase/tutorial/reflect/member/methodparameterreflection.html

I can open a pull request if this seems like an appropriate fix.

[eskatos]

#437 (comment)
Upon further inspection this seems to be caused by Kotlin interface delegation (... : Project by project { ...) not preserving the parameter names in the generated bytecode.

Parameter names show up correctly for non delegated members, for instance, notice the version parameter below:

[AlexCzar]

@eskatos I searched Kotlin's issue tracker but couldn't find this specific problem. Was it reported?

[eskatos]

@AlexCzar not that I know of, feel free to report it upstream, I'll get back to it next week if you don't beat me to it.

It doesn't happen when no .kts file is involved.
I didn't try and reproduce outside of the Kotlin DSL yet.

[eskatos]

Reported upstream: https://youtrack.jetbrains.com/issue/KT-22210

[bamboo]

Moved to backlog so we can decide if we should tackle it ourselves.

[eskatos]

Two candidate solutions until Gradle is built with Java 8 and -parameters:

• have a parameter names index in the Gradle distribution and enhance the Gradle API Jar before passing it to the Kotlin compiler in the Kotlin DSL build
• building all Gradle modules with Java 8 and -parameters, publish them and use them instead of gradleApi() in the Kotlin DSL build

[bamboo]

Tracked it down to https://youtrack.jetbrains.com/issue/KT-25193

[JLLeitschuh]

Good find!

[eskatos]

A workaround is mentioned in https://youtrack.jetbrains.com/issue/KT-25193#comment=27-2957572

As a temporary workaround, you can use the compiler argument -Xuse-old-class-files-reading.

Description of that argument is Use old class files reading implementation (may slow down the build and should be used in case of problems with the new implementation)

See https://github.com/JetBrains/kotlin/blob/094cb6be1d351022a1d6a8cdcd1c30f74a6c82e3/compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt#L148-L153

[eskatos]

Made an attempt with -java-parameters and -Xuse-old-class-files-reading in 28cc2ec without success, doesn't work from the cli nor in the ide.

[eskatos]

Adding -Xuse-old-class-files-reading to the small reproducer build works: https://github.com/bamboo/kotlin-parameter-names

To make all this work we'd need the Gradle API jar bytecode to include parameter names.

[JLLeitschuh]

🎆 🎉 👍 🎉 🎆