unsupported lint option: redundantNullComparison

[mkondratek]

Hi!

I have encountered some problem related to lint options.

My Gradle check (compileJava actually) task result fails with:
warning: Unsupported lint option: redundantNullComparison; All options: [cast, debugSpew, cast:redundant, cast:unsafe] error: warnings found and -Werror specified

A part of build.gradle:

plugins {
  //...
  id 'org.checkerframework' version '0.4.14' apply false
}

subprojects {
  //...
  apply plugin: 'org.checkerframework'
  checkerFramework {
    excludeTests = true
    checkers = [
      'org.checkerframework.checker.formatter.FormatterChecker',
      'org.checkerframework.checker.guieffect.GuiEffectChecker',
      'org.checkerframework.checker.index.IndexChecker',
      'org.checkerframework.checker.nullness.NullnessChecker',
      'org.checkerframework.checker.optional.OptionalChecker',
      'org.checkerframework.checker.regex.RegexChecker',
    ]
    extraJavacArgs = [
            '-Alint=redundantNullComparison',
            '-AassumeAssertionsAreEnabled',
            "-Astubs=$rootDir/config/checker/",
            '-AsuppressWarnings=type.anno.before.modifier',
    ]
  }
}

org.checkerframework version: 0.4.14

[wmdietl]

Thanks for the report!
This can be reproduced on the command-line and isn't an issue of the gradle plugin.
I'll try transferring the issue to typetools/checker-framework...

The issue can be reproduced with only nullness and guieffect checkers.
Those are the only two that have supported lint options:
https://github.com/typetools/checker-framework/blob/master/checker/src/main/java/org/checkerframework/checker/guieffect/GuiEffectChecker.java#L9
https://github.com/typetools/checker-framework/blob/master/checker/src/main/java/org/checkerframework/checker/nullness/NullnessChecker.java#L19

The mechanism to select the type system doesn't seem to work, though, and isn't documented. I'll fix this.

[wmdietl]

@kelloggm I can't transfer the issue. Can you?

[kelloggm]

@wmdietl It seems like GitHub doesn't permit transfers between repositories that aren't owned by the same account. I've transferred it to my fork of the CF, but that's probably not what you had in mind :)

It might be better to open a new issue on the CF itself and close this one.

[wmdietl]

That seems good enough...

The fix is here
typetools#3239
and I'll add a reference to this issue.

[wmdietl]

Each -processor is executed independently, so when we check the supported lint flags for one checker, we don't know whether there is another checker that might support that flag.

So it is unfortunately required that this invocation:

/checker/bin/javac -Alint=redundantNullComparison
 -processor nullness,guieffect  Repro.java
Repro.java:8: warning: [known.nonnull] redundant check; "o" is non-null
            if (o == null) {
                  ^
warning: Unsupported lint option: redundantNullComparison; All options: [cast, debugSpew, cast:redundant, cast:unsafe]
2 warnings

issues a warning.

Once the fix in typetools#3239 is merged (and the next time we made a release), you can use one of the following two ways to pass the flag only to the correct checker:

$ ./checker/bin/javac -Aorg.checkerframework.checker.nullness.NullnessChecker_lint=redundantNullComparison -processor nullness,guieffect  Repro.java
Repro.java:8: warning: [known.nonnull] redundant check; "o" is non-null
            if (o == null) {
                  ^
1 warning

$ ./checker/bin/javac -ANullnessChecker_lint=redunda
ntNullComparison -processor nullness,guieffect  Repro.java
Repro.java:8: warning: [known.nonnull] redundant check; "o" is non-null
            if (o == null) {
                  ^
1 warning