Hi ! I will try to repost my question :confused: `...

# android

[Gabriele Rugani]

Hi !
I will try to repost my question 😕

What could happen if I would use different libraries with different kotlin version ?

Do you update your project's kotlin language's version only when all the imported libraries are updated ?

[ephemient]

https://kotlinlang.org/docs/components-stability.html
https://kotlinlang.org/docs/language-committee-guidelines.html#availability-of-the-standard-library

[Gabriele Rugani]

Thanks ! I will read all the documentation 🙂
I asked because gradle tell to me:

Runtime JAR files in the classpath should have the same version. These
files were found in the classpath:

and

w: Consider providing an explicit dependency on kotlin-reflect 1.5 to
prevent strange errorsw: Some runtime JAR files in the classpath have
an incompatible version. Consider removing them from the classpath

[ephemient]

use kotlin-bom to keep versions aligned, that can happen if you have dependencies on older kotlin-reflect that you yourself aren't directly depending on

[Gabriele Rugani]

I don't already read the links, but what happen if a library that I'm import, uses an old version of kotlin (such as 1.3) and I have set the 1.5 in the project ?
In this case I suppose gradle gives me an error, but in which way the project can build and run ? What happen ff the library uses a method that doesnt exist anymore in 1.5 ?
Maybe the answer is in the documentation that you sent to me, sorry !
(Maybe I misunderstanding the gradle's error)

[ephemient]

if you're using Kotlin/JVM, it works fine. the standard library is backwards-compatible and does not remove stable APIs from the ABI. (sometimes they may be removed from the API, but in a way that preserves ABI compatibliity)

[ephemient]

the problem is that all of the standard library should be aligned - that includes kotlin-stdlib (which your build pulls in automatically) and kotlin-reflect (which it doesn't). if you used

dependencies {
    implementation(platform(kotlin("bom"))) // Kotlin Gradle DSL
    implementation platform("org.jetbrains.kotlin:kotlin-bom:$kotlin_version") // Groovy Gradle DSL (probably, I don't use it)
}

then Gradle will make sure all the standard library artifact versions are aligned, regardless of which ones are included transitively

[ephemient]

there is no forwards compatibility - you can't use a library compiled with a newer major release of Kotlin without issues - but there is a promise of backwards compatibility, at least for Kotlin/JVM. (does not apply to multiplatform)

[ephemient]

please read the documentation to understand what is in scope and what isn't.

[Gabriele Rugani]

Thanks ! You are the best ! I will read ! I am ashamed of my ignorance..

[Colton Idle]

@ephemient I didn't know that kotlin had a bom! Cool thanks

[ephemient]

bom discoverability is definitely an issue in the maven ecosystem… something that could be better in gmm https://blog.gradle.org/alignment-with-gradle-module-metadata

[Gabriele Rugani]

Hi @ephemient , good morning !
I read the two link:
In the first one I understand that: "Many of these components were officially released as Stable which means that they are evolved in the backward-compatible way following the principles of Comfortable Updates and Keeping the Language Modern"
In the second link: "The Kotlin Language Committee has to approve every incompatible change before it lands in a stable version."

But I'm wondering, how an "incompatible change" can be backward-compatible ?

[ephemient]

there are source-level incompatible changes that are binary-level compatible

[Gabriele Rugani]

Thanks 🙂
I add this code line into app's gradle:

implementation(platform("org.jetbrains.kotlin:kotlin-bom"))

but when I execute the clean task the warning appears:

Task :buildSrc:compileKotlin
w: Runtime JAR files in the classpath should have the same version. These files were found in the classpath:
    C:/Users/""/.gradle/wrapper/dists/gradle-6.7.1-all/2moa8rlfac5eqlcfgk98k0deb/gradle-6.7.1/lib/kotlin-stdlib-1.3.72.ja
r (version 1.3)
    C:/Users/""/.gradle/wrapper/dists/gradle-6.7.1-all/2moa8rlfac5eqlcfgk98k0deb/gradle-6.7.1/lib/kotlin-stdlib-common-1.
3.72.jar (version 1.3)
    C:/Users/""/.gradle/wrapper/dists/gradle-6.7.1-all/2moa8rlfac5eqlcfgk98k0deb/gradle-6.7.1/lib/kotlin-stdlib-jdk7-1.3.
72.jar (version 1.3)
    C:/Users/""/.gradle/wrapper/dists/gradle-6.7.1-all/2moa8rlfac5eqlcfgk98k0deb/gradle-6.7.1/lib/kotlin-stdlib-jdk8-1.3.
72.jar (version 1.3)
    C:/Users/""/.gradle/wrapper/dists/gradle-6.7.1-all/2moa8rlfac5eqlcfgk98k0deb/gradle-6.7.1/lib/kotlin-reflect-1.3.72.j
ar (version 1.3)
    C:/Users/""/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jdk8/1.5.0/65fbc439df2e4aad1f376976
2d54534f1b564090/kotlin-stdlib-jdk8-1.5.0.jar (version 1.5)
    C:/Users/""/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jdk7/1.5.0/f61904618ea7be07a66e0545
ffe8dc2c70a19b77/kotlin-stdlib-jdk7-1.5.0.jar (version 1.5)
    C:/Users/""/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-reflect/1.4.31/63db9d66c3d20f7b8f66196e7ba
86969daae8b8a/kotlin-reflect-1.4.31.jar (version 1.4)
    C:/Users/""/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib/1.5.0/29dae2501ca094416d15af0e21470
cb634780444/kotlin-stdlib-1.5.0.jar (version 1.5)
    C:/Users/""/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-common/1.5.0/4080d69efca5e39e9b4972
f125e40f1607bd6460/kotlin-stdlib-common-1.5.0.jar (version 1.5)
w: Consider providing an explicit dependency on kotlin-reflect 1.5 to prevent strange errors
w: Some runtime JAR files in the classpath have an incompatible version. Consider removing them from the classpath

I'm not understanding anything.. 😥

[ephemient]

wait, are you doing this inside Gradle buildSrc or plugin?

[ephemient]

because you cannot use newer Kotlin version there, due to Gradle issues. inside build.gradle.kts or any buildscript in a project using Gradle Kotlin DSL, you can only use the same version of Kotlin that is bundled in Gradle

[ephemient]

https://github.com/gradle/gradle/issues/16345

[Gabriele Rugani]

The error is only in buildSrccompileKotlin, there aren't error during the compilation of other's app module.

I have imported the

implementation(platform("org.jetbrains.kotlin:kotlin-bom"))

in the app's gradle.

In the buildSrc I have devoloped a task to get the jacoco-plugin coverage, and I'm importing the last gradle version:

apply plugin: 'java-gradle-plugin'
apply plugin: 'kotlin' 

buildscript {
    ext.gradle_version = '4.2.1'
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.0"
        classpath "com.android.tools.build:gradle:$gradle_version"
    }
}

repositories {
    google()
    jcenter()
}

dependencies {
    // Android gradle plugin will allow us to access Android specific features
    implementation "com.android.tools.build:gradle:$gradle_version"
    implementation "com.android.tools.build:gradle-api:$gradle_version"
}

gradlePlugin {
    plugins {
        create("AndroidCoveragePlugin") {
            id = "AndroidCoveragePlugin"
            implementationClass = "com.myApp.buildtools.AndroidCoveragePlugin"
        }
    }
}

Inside agp 4.2.1 there aren't kotlin 1.5.0 ?

[ephemient]

no

[ephemient]

Lint does bundle yet another Kotlin version, but it's in a different classloader

[Gabriele Rugani]

Gradle is tested with Kotlin 1.3.21 through 1.4.0.
.....
Which it means I can't resolve the issue, if I would keep the project to the last kotlin version. In this case I have to live with the warning, and I have to hope that the gradle plugin continue to working well.

[ephemient]

no, that's not what it means.

[ephemient]

at least upgrade to Gradle 6.8.or 6.9 - they embed Kotlin 1.4, although still using 1.3 syntax in build.gradle.kts for compatibility reasons

[ephemient]

Gradle 7 build scripts can use Kotlin 1.4 in full

[Gabriele Rugani]

I have upgraded to gradle 6.8 and I have set the plugin to the kotlin version 1.4.32 and I have add the kotlin-reflect 1.4.32.
Now it works without warning ! Thanks @ephemient!