gradle-errorprone-plugin
This plugin configures JavaCompile
tasks to use the Error Prone compiler.
Requirements
This plugin requires using at least Gradle 5.2.
While JDK 8 is supported, it is recommended to use at least a JDK 9 compiler. See note below about JDK 8 support.
Usage
plugins {
id("net.ltgt.errorprone") version "<plugin version>"
}
Note: snippets in this guide use features from the latest Gradle version, so beware if copy/pasting.
This plugin creates a configuration named errorprone
, and configures the <sourceSet>AnnotationProcessor
configuration for each source set to extend it. This allows configuring Error Prone dependencies from a single place.
Error Prone needs to be added as a dependency in this configuration:
repositories {
mavenCentral()
}
dependencies {
errorprone("com.google.errorprone:error_prone_core:$errorproneVersion")
}
CAUTION: Using a dynamic or changing version for Error Prone, such as latest.release
or 2.+
, means that your build could fail at any time, if a new version of Error Prone adds or enables new checks that your code would trigger.
Error Prone can then be configured on the JavaCompile
tasks:
tasks.withType(JavaCompile).configureEach {
options.errorprone.disableWarningsInGeneratedCode = true
}
with Kotlin DSL
import net.ltgt.gradle.errorprone.errorprone
tasks.withType<JavaCompile>().configureEach {
options.errorprone.disableWarningsInGeneratedCode.set(true)
}
and can also be disabled altogether:
tasks.named("compileTestJava").configure {
options.errorprone.enabled = false
}
with Kotlin DSL
tasks.named<JavaCompile>("compileTestJava") {
options.errorprone.isEnabled.set(false)
}
Note that this plugin only enables Error Prone on tasks for source sets (i.e. compileJava
for the main
source set, compileTestJava
for the test
source set, and compileIntegTestJava
for a custom integTest
source set). If you're creating custom JavaCompile
tasks, then you'll have to configure them manually to enable Error Prone:
tasks.register("compileCustom", JavaCompile) {
source "src/custom/"
include "**/*.java"
classpath = configurations.custom
sourceCompatibility = "8"
targetCompatibility = "8"
destinationDir = file("$buildDir/classes/custom")
// Error Prone must be available in the annotation processor path
options.annotationProcessorPath = configurations.errorprone
// Enable Error Prone
options.errorprone.enabled = true
// It can then be configured for the task
options.errorprone.disableWarningsInGeneratedCode = true
}
with Kotlin DSL
tasks.register<JavaCompile>("compileCustom") {
source("src/custom/")
include("**/*.java")
classpath = configurations["custom"]
sourceCompatibility = "8"
targetCompatibility = "8"
destinationDir = file("$buildDir/classes/custom")
// Error Prone must be available in the annotation processor path
options.annotationProcessorPath = configurations["errorprone"]
// Enable Error Prone
options.errorprone.isEnabled.set(true)
// It can then be configured for the task
options.errorprone.disableWarningsInGeneratedCode.set(true)
}
In Android projects, tasks cannot be configured until afterEvaluate
due to how the Android Plugin for Gradle works:
afterEvaluate {
tasks.withType(JavaCompile).configureEach {
options.errorprone.disableWarningsInGeneratedCode = true
}
}
with Kotlin DSL
afterEvaluate {
tasks.withType<JavaCompile>().configureEach {
options.errorprone.disableWarningsInGeneratedCode.set(true)
}
}
JDK 8 support
Error Prone requires at least a JDK 9 compiler. When using a JDK 8 compiler, you can configure a dependency on the Error Prone javac in the errorproneJavac
configuration:
dependencies {
errorproneJavac("com.google.errorprone:javac:9+181-r4173-1")
}
and the plugin will configure the JavaCompile
tasks to use a forking compiler and will override the compiler by prepending the dependencies to the bootstrap classpath (using a -Xbootclasspath/p:
JVM argument).
Starting with Gradle 6.7, you can configure JavaCompile
tasks to use a specific JDK compiler, independently of the JDK used to run Gradle itself. The plugin will use the toolchain version, if any is specified, to configure the task. This allows you to enforce compilation with JDK 8 (properly configured for Error Prone!) while running Gradle with e.g. JDK 11, or the reverse: enforce compilation with JDK 11 while running Gradle with JDK 8.
Alternatively, or for previous versions of Gradle, you can configure JavaCompile
tasks to use such a JDK while still using JDK 8 for running Gradle:
tasks.withType(JavaCompile).configureEach {
options.fork(javaHome: project.getProperty("jdk11home"))
}
with Kotlin DSL
tasks.withType<JavaCompile>().configureEach {
options.fork = true
options.forkOptions.javaHome = project.getProperty("jdk11home")
}
The plugin will try to detect those cases and won't configure the bootstrap classpath in this case, but to play safe it will actually ignore any task that forks and defines either a javaHome
or an executable
(this also means that it won't configure the bootstrap classpath if you're e.g. running Gradle with a more recent JDK and forking the compilation tasks to use JDK 8).
If you need it, you can configure the bootstrap classpath manually for those tasks that the plugin would have skipped:
someTask.configure {
// …
inputs.files(configurations.errorproneJavac).withNormalizer(ClasspathNormalizer)
doFirst {
options.forkOptions.jvmArgs += "-Xbootclasspath/p:${configurations.errorproneJavac.asPath}"
}
}
with Kotlin DSL
someTask.configure {
// …
inputs.files(configurations.errorproneJavac).withNormalizer(ClasspathNormalizer::class)
doFirst {
options.forkOptions.jvmArgs.add("-Xbootclasspath/p:${configurations["errorproneJavac"].asPath}")
}
}
(if you're using forkOptions.executable
, then use -J-Xbootclasspath/p:
instead.)
Migration from versions 0.0.x
If you relied on the default Error Prone dependency (which you shouldn't have, see warning above about changing versions), you'll have to configure it explicitly (see above). If you need to support building with JDK 8, you'll need to configure the Error Prone javac dependency (see above).
Contrary to versions 0.0.x, later versions use a DSL to configure Error Prone, and passing Error Prone-specific arguments to options.compilerArgs
won't work. As an easy migration step, you can pass those arguments to options.errorprone.errorproneArgs
instead:
tasks.withType(JavaCompile).configureEach {
- options.compilerArgs << "-Xlint:all" << "-Werror" << "-XepDisableWarningsInGeneratedCode"
- options.compilerArgs << "-Xep:NullAway:ERROR" << "-XepOpt:NullAway:AnnotatedPackages=net.ltgt"
+ options.compilerArgs << "-Xlint:all" << "-Werror"
+ options.errorprone.errorproneArgs.add("-XepDisableWarningsInGeneratedCode")
+ options.errorprone.errorproneArgs.addAll("-Xep:NullAway:ERROR", "-XepOpt:NullAway:AnnotatedPackages=com.uber")
}
The next (optional) step would be to move to using the DSL:
tasks.withType(JavaCompile).configureEach {
options.compilerArgs << "-Xlint:all" << "-Werror"
- options.errorprone.errorproneArgs.add("-XepDisableWarningsInGeneratedCode")
- options.errorprone.errorproneArgs.addAll("-Xep:NullAway:ERROR", "-XepOpt:NullAway:AnnotatedPackages=com.uber")
+ options.errorprone {
+ disableWarningsInGeneratedCode = true
+ error("NullAway")
+ option("NullAway:AnnotatedPackages", "net.ltgt")
+ }
}
Finally, the net.ltgt.errorprone-base
plugin is removed without replacement. In most cases, it can be replaced by disabling or enabling Error Prone on selected tasks.
Custom Error Prone checks
This requires Error Prone 2.3.0 or later.
Custom Error Prone checks can be added to the errorprone
configuration too:
dependencies {
errorprone("com.uber.nullaway:nullaway:$nullawayVersion")
}
or alternatively to the <sourceSet>AnnotationProcessor
configuration, if they only need to be enabled for a given source set:
dependencies {
annotationProcessor("com.google.guava:guava-beta-checker:$betaCheckerVersion")
}
and can then be configured on the tasks; for example:
tasks.withType(JavaCompile).configureEach {
options.errorprone {
option("NullAway:AnnotatedPackages", "net.ltgt")
}
}
tasks.named("compileJava").configure {
// The check defaults to a warning, bump it up to an error for the main sources
options.errorprone.error("NullAway")
}
with Kotlin DSL
tasks.withType<JavaCompile>().configureEach {
options.errorprone {
option("NullAway:AnnotatedPackages", "net.ltgt")
}
}
tasks.named("compileJava", JavaCompile::class) {
// The check defaults to a warning, bump it up to an error for the main sources
options.errorprone.error("NullAway")
}
Configuration
As noted above, this plugin adds an errorprone
extension to the JavaCompile.options
. It can be configured either as a property (options.errorprone.xxx = …
) or script block (options.errorprone { … }
).
In a *.gradle.kts
script, the Kotlin extensions need to be imported:
import net.ltgt.gradle.errorprone.errorprone
Properties
Please note that all properties are lazy, so while you can use =
in place of .set(…)
in the Groovy DSL, you cannot use <<
or +=
to add to lists for instance.
Property | Description |
---|---|
enabled |
(isEnabled with Kotlin DSL) Allows disabling Error Prone altogether for the task. Error Prone will still be in the annotation processor path, but -Xplugin:ErrorProne won't be passed as a compiler argument. Defaults to true for source set tasks, false otherwise. |
disableAllChecks |
Disable all Error Prone checks; maps to -XepDisableAllChecks . This will be the first argument, so checks can then be re-enabled on a case-by-case basis. Defaults to false . |
disableAllWarnings |
Maps to -XepDisableAllWarnings (since ErrorProne 2.4.0). Defaults to false . |
allErrorsAsWarnings |
Maps to -XepAllErrorsAsWarnings . Defaults to false . |
allDisabledChecksAsWarnings |
Enables all Error Prone checks, checks that are disabled by default are enabled as warnings; maps to -XepDisabledChecksAsWarnings . Defaults to false . |
disableWarningsInGeneratedCode |
Disables warnings in classes annotated with javax.annotation.processing.Generated or @javax.annotation.Generated ; maps to -XepDisableWarningsInGeneratedCode . Defaults to false . |
ignoreUnknownCheckNames |
Maps to -XepIgnoreUnknownCheckNames . Defaults to false . |
ignoreSuppressionAnnotations |
Maps to -XepIgnoreSuppressionAnnotations (since Error Prone 2.3.3). Defaults to false . |
compilingTestOnlyCode |
(isCompilingTestOnlyCode with Kotlin DSL) Maps to -XepCompilingTestOnlyCode . Defaults to false . (defaults to true for a source set inferred as a test source set) |
excludedPaths |
A regular expression pattern (as a string) of file paths to exclude from Error Prone checking; maps to -XepExcludedPaths . Defaults to null . |
checks |
A map of check name to CheckSeverity , to configure which checks are enabled or disabled, and their severity; maps each entry to -Xep:<key>:<value> , or -Xep:<key> if the value is CheckSeverity.DEFAULT . Defaults to an empty map. |
checkOptions |
A map of check options to their value; maps each entry to -XepOpt:<key>=<value> . Use an explicit "true" value for a boolean option. Defaults to an empty map. |
errorproneArgs |
Additional arguments passed to Error Prone. Defaults to an empty list. |
errorproneArgumentProviders |
A list of CommandLineArgumentProvider for additional arguments passed to Error Prone. Defaults to an empty list. |
Methods
Method | Description |
---|---|
enable(checkNames...) |
Adds checks with their default severity. Useful in combination with disableAllChecks to selectively re-enable checks. Equivalent to check(checkName, CheckSeverity.DEFAULT) for each check name. |
disable(checkNames...) |
Disable checks. Equivalent to check(checkName, CheckSeverity.OFF) for each check name. |
warn(checkNames...) |
Adds checks with warning severity. Equivalent to check(checkName, CheckSeverity.WARNING) for each check name. |
error(checkNames...) |
Adds checks with error severity. Equivalent to check(checkName, CheckSeverity.OFF) for each check name. |
check(checkName to severity...) |
(Kotlin DSL only) Adds pairs of check name to severity. Equivalent to checks.put(first, second) for each pair. |
check(checkName, severity) |
Adds a check with a given severity. The severity can be passed as a provider for lazy configuration. Equivalent to checks.put(checkName, severity) . |
option(optionName) |
Enables a boolean check option. Equivalent to option(checkName, true) . |
option(optionName, value) |
Adds a check option with a given value. Value can be a boolean or a string, or a provider of string. Equivalent to checkOptions.put(name, value) . |
A check severity can take values: DEFAULT
, OFF
, WARN
, or ERROR
.
Note that the net.ltgt.gradle.errorprone.CheckSeverity
needs to be import
ed into your build scripts (see examples above).