warning: [unchecked] unchecked method invocation: method singletonMap in class Collections is applied to given types

[jaredsburrows]

Can suppress unchecked in the generated code to prevent warnings during compilation?

Issue:

warning: [unchecked] unchecked method invocation: method singletonMap in class Collections is applied to given types

Error:

$ gradlew assembleDEbug

> Task :compileDebugJavaWithJavac FAILED
/Users/<>/repo/android-gif-example/build/generated/source/kapt/debug/burrows/apps/example/gif/presentation/di/component/DaggerAppComponent.java:60: warning: [unchecked] unchecked method invocation: method singletonMap in class Collections is applied to given types
            singletonMap(MainActivity.class, (Provider) mainActivitySubcomponentBuilderProvider);
                        ^
  required: K,V
  found: Class<MainActivity>,Provider
  where K,V are type-variables:
    K extends Object declared in method <K,V>singletonMap(K,V)
    V extends Object declared in method <K,V>singletonMap(K,V)
/Users/<>/repo/android-gif-example/build/generated/source/kapt/debug/burrows/apps/example/gif/presentation/di/component/DaggerAppComponent.java:60: warning: [unchecked] unchecked conversion
            singletonMap(MainActivity.class, (Provider) mainActivitySubcomponentBuilderProvider);
                                             ^
  required: V
  found:    Provider
  where V,K are type-variables:
    V extends Object declared in method <K,V>singletonMap(K,V)
    K extends Object declared in method <K,V>singletonMap(K,V)
/Users/<>/repo/android-gif-example/build/generated/source/kapt/debug/burrows/apps/example/gif/presentation/di/component/DaggerAppComponent.java:60: warning: [unchecked] unchecked conversion
            singletonMap(MainActivity.class, (Provider) mainActivitySubcomponentBuilderProvider);
                        ^
  required: Map<Class<? extends Activity>,Provider<Factory<? extends Activity>>>
  found:    Map
error: warnings found and -Werror specified
1 error
3 warnings


FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 9s
17 actionable tasks: 16 executed, 1 up-to-date

Temp fix:

"-Xlint:-unchecked"

[ronshapiro]

Shouldn't we be specifying type parameters there (

dagger/java/dagger/internal/codegen/MapBindingExpression.java

Lines 134 to 140 in beeb29d

	private CodeBlock maybeTypeParameters(ClassName requestingClass) {
	TypeMirror bindingKeyType = binding.key().type();
	MapType mapType = MapType.from(binding.key());
	return isTypeAccessibleFrom(bindingKeyType, requestingClass.packageName())
	? CodeBlock.of("<$T, $T>", mapType.keyType(), mapType.valueType())
	: CodeBlock.of("");
	}

)?

Can you provide a failing example?

[jaredsburrows]

@ronshapiro A failing example? The code above fails with -Werror or will simply produce the following warnings and not fail the build.

The specific line is: singletonMap(MainActivity.class, (Provider) mainActivitySubcomponentBuilderProvider);.

[ronshapiro]

I meant a small repo that exhibits the issue (that we can test+verify a fix on)

[jaredsburrows]

@ronshapiro Oh sorry, I usually add that in the description. Here are the repro steps:

1. git clone https://github.com/jaredsburrows/android-gif-example
2. cd android-gif-example
3. Comment out or remove add("-Xlint:-unchecked") from https://github.com/jaredsburrows/android-gif-example/blob/master/gradle/compile.gradle.kts#L16
4. graldew assembleDebug

[jaredsburrows]

Any update on this?

[ronshapiro]

I see what's happening - there's a @Binds method that is being requested as a provider, which causes Dagger to cast to a rawtype.

Unfortunately, I don't know of a good way to fix this without suppressing warnings over far too much code.

[ronshapiro]

Actually, we may be able to check in MapBindingExpression if the type is the erasure but could be the accessible type. This should also probably happen in other places where BindingExpressions are composed too.

[gildor]

@ronshapiro Any updates? I suppose that would be better to suppress warning if it's hard/impossible to fix, after all this is generated code. This cause problem with real problems detection using -Werror option.
Also in my case I see additional warning:

unchecked call to put(K,V) as a member of the raw type MapBuilder

for the generated code of method getMapOfClassOfAndProviderOfFactoryOf2 that puts my dagger-android providers for activity to MapBuilder

[ronshapiro]

I'm leaning towards an approach like this one: #1248 (comment)

[gildor]

It's little bit unfortunate that it cannot be fixed on side of dagger, but approach form your comment still works and allows use -Werror