How to add -Xlint:unchecked to Gradle *from command line*?

Question

Our old code bases use deprecated and unchecked APIs from time to time, and we get these in the output:

Note: C:\path\to\MyClass.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

Ok, so how do I recompile with with -Xlint:unchecked from the command line, without changing build.gradle? Many other answers show how to fix it by adding this to build.gradle (or similar to build.gradle.kts):

gradle.projectsEvaluated {
   tasks.withType(JavaCompile) {
        options.compilerArgs << "-Xlint:unchecked" << "-Xlint:deprecation"
    }
}

but that requires editing files (creating git diffs) and is just a pain in the... Is there some way, environment variable, command-line option or something to add compiler args without touching the build.gradle* files?

Answer 1

As far as I know, this is not possible. You definitely need to configure the respective CompileOptions of the JavaExec tasks using the Gradle API. The easiest way to do this is in fact the build.gradle file. If you just want to keep the changes to build.gradle to a minimum, consider using a project property:

if (hasProperty('compilerArgs')) {
    gradle.projectsEvaluated {
        tasks.withType(JavaCompile) {
            compilerArgs.split().each { arg ->
                options.compilerArgs << arg
            }
        }
    }
}

This way you won't need to change your build.gradle from now on to change your compiler arguments, as you may simply pass them using gradle <tasks> -PcompilerArgs="<arg1> <arg2>". Project properties may also be defined using environment variables.

An alternative without touching the build.gradle at all is the use of initialization scripts. These scripts in your home directory apply to any Gradle build performed using your account, so you may add some restrictions if you have other projects that should not be effected. A simple initialization script for your use case could be:

allprojects {
    gradle.projectsEvaluated {
        tasks.withType(JavaCompile) {
            options.compilerArgs << "-Xlint:unchecked" << "-Xlint:deprecation"
        }
    }
}

You may combine this with the approach from my first snippet to only apply the changes based on a command line argument.

You need to put this into a file

• specified on the command line using -I or --init-script
• called init.gradle in the USER_HOME/.gradle/ directory
• that ends with .gradle in the USER_HOME/.gradle/init.d/ directory
• that ends with .gradle in the GRADLE_HOME/init.d/ directory

Of course, those changes need to be applied to any user / any machine.