How do I make the Kotlin compiler treat warnings as errors?

Question

I have a Kotlin project where I'd like to have Kotlin warnings treated as errors. How can I do that?

In what build system, or IDE? the answer might be different. (I've never seen this option available, but to be sure be clear about in what build system this would be applicable) — Jayson Minard, Jan 02 '16 at 03:34
Do you have the source of this project on Github? Are you using Gradle and Intellij? — Jared Burrows, Jan 02 '16 at 05:42
@JaredBurrows https://github.com/jeffcharles/visitor-detector. A very early and still in development version. Yes and yes to Gradle and Intellij. — Jeffrey Charles, Jan 04 '16 at 01:54

Alexander Udalov · Accepted Answer · 2017-10-24T15:46:50.043

47

Since Kotlin 1.2, the command line argument -Werror is supported. In Gradle, it's named allWarningsAsErrors:

compileKotlin {
    kotlinOptions.allWarningsAsErrors = true
}

edited Oct 24 '17 at 15:46

answered Sep 15 '17 at 17:27

Alexander Udalov

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4

Which block of `build.gradle` does this need to be added to? – karl Dec 13 '17 at 23:22
1

@karl I think this should be on the top level. Please refer to the official documentation: https://kotlinlang.org/docs/reference/using-gradle.html#compiler-options – Alexander Udalov Dec 20 '17 at 12:37
4

Thanks. From the docs, for future reference: for an Android project, the task name will include the build variant (i.e. `compileDebugKotlin`), but you can add it to all tasks by using `tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all { kotlinOptions { ... } }` – karl Dec 20 '17 at 20:20
5

For Android: inside `allprojects` block of project level `build.gradle` file, add: `tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all { kotlinOptions.allWarningsAsErrors = true }` – Piotr Aleksander Chmielowski Sep 02 '19 at 19:54

score 11 · Answer 2 · answered May 12 '20 at 09:38

11

With recent versions of the Android Gradle plug-in, one can simply do this:

android {
    kotlinOptions {
        kotlinOptions.allWarningsAsErrors = true
    }

    ...
}

answered May 12 '20 at 09:38

Enselic

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Jayson Minard · Answer 3 · 2022-03-12T05:19:04.840

9

This does not appear to be currently available in the Kotlin command-line help, or arguments available to the Kotlin compiler:

K2JVMCompilerArguments.java

and

CommonCompilerArguments.java

But some people in Gradle do things like this to scan logging of the compiler to know when a warning was generated. How to fail gradle build on Javadoc warnings

Within the IDE Plugins available for Kotlin (Intellij IDEA and Eclipse) there is no such option.

You should file a feature request (or check if one already exists) in YouTrack which has all the issue tracking for the Kotlin project. And if you do so, please post the issue here so it can be tracked.

edited Mar 12 '22 at 05:19

answered Jan 02 '16 at 03:37

Jayson Minard

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Feature request filed at https://youtrack.jetbrains.com/issue/KT-10563 – Jeffrey Charles Jan 04 '16 at 02:04
Writing something in Gradle in the meantime is a reasonable idea. It's not high enough priority for me to justify the effort for that right now but I'll consider it in the future. – Jeffrey Charles Jan 04 '16 at 02:09
they schedule this improvement to 1.2? why there is no any VOTE button there – William Leung Mar 10 '17 at 09:49

score 2 · Answer 4 · answered Jan 17 '20 at 13:30

2

If you are using android use this instead. In Android we don't have compileKotlin but rather compileDebugKotlin, compileReleaseKotlin, etc. So we have to loop through them and add this configuration to all of them.

tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
    kotlinOptions {
        kotlinOptions.allWarningsAsErrors = true
    }
}

answered Jan 17 '20 at 13:30

Alireza Ahmadi

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For AndroidStudio 3.5, I put the above block within `allprojects` block at top level of ./app/build.gradle file, and that worked for me. – Daniel Mar 13 '20 at 18:38

score 2 · Answer 5 · answered Feb 19 '20 at 10:07

2

With the Kotlin DSL:

tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
    kotlinOptions {
        kotlinOptions.allWarningsAsErrors = true
    }
}

answered Feb 19 '20 at 10:07

LiorH

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score 0 · Answer 6 · answered Feb 01 '23 at 16:46

0

Extending LiorH's answer, here's kotlin DSL if you want to enable the warnings as errors only for release builds:

tasks.withType<KotlinCompile>().configureEach {
    kotlinOptions.allWarningsAsErrors = name.contains("Release")
}

answered Feb 01 '23 at 16:46

Zaffy

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How do I make the Kotlin compiler treat warnings as errors?

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