Can't find Composer Class when Building

Question

I'm trying to add compose to my existing project and getting the following exception when building

e: java.lang.IllegalStateException: Cannot find the Composer class
    at androidx.compose.plugins.kotlin.compiler.lower.AbstractComposeLowering.<init>(AbstractComposeLowering.kt:156)
    at androidx.compose.plugins.kotlin.compiler.lower.ComposerLambdaMemoization.<init>(ComposerLambdaMemoization.kt:146)
    at androidx.compose.plugins.kotlin.ComposeIrGenerationExtension.generate(ComposeIrGenerationExtension.kt:55)
    at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade$doGenerateFiles$1.invoke(JvmBackendFacade.kt:37)
    at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade$doGenerateFiles$1.invoke(JvmBackendFacade.kt:24)
    at org.jetbrains.kotlin.psi2ir.Psi2IrTranslator.postprocess(Psi2IrTranslator.kt:93)
    at org.jetbrains.kotlin.psi2ir.Psi2IrTranslator.generateModuleFragment(Psi2IrTranslator.kt:78)
    at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade.doGenerateFiles(JvmBackendFacade.kt:51)
    at org.jetbrains.kotlin.backend.jvm.JvmIrCodegenFactory.generateModule(JvmIrCodegenFactory.kt:37)
    at org.jetbrains.kotlin.codegen.KotlinCodegenFacade.compileCorrectFiles(KotlinCodegenFacade.java:35)
    at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.generate(KotlinToJVMBytecodeCompiler.kt:635)
    at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli(KotlinToJVMBytecodeCompiler.kt:194)
    at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:163)
    at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:51)
    at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:86)
    at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:44)
    at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:104)
    at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:346)
    at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:102)
    at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally(IncrementalCompilerRunner.kt:240)
    at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.access$compileIncrementally(IncrementalCompilerRunner.kt:39)
    at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner$compile$2.invoke(IncrementalCompilerRunner.kt:81)
    at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compile(IncrementalCompilerRunner.kt:93)
    at org.jetbrains.kotlin.daemon.CompileServiceImplBase.execIncrementalCompiler(CompileServiceImpl.kt:606)
    at org.jetbrains.kotlin.daemon.CompileServiceImplBase.access$execIncrementalCompiler(CompileServiceImpl.kt:99)
    at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:1645)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.

I have the following in my build.gradle

implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.72")
//...
implementation("androidx.ui:ui-framework:0.1.0-dev10")
implementation("androidx.ui:ui-tooling:0.1.0-dev10")
implementation("androidx.ui:ui-layout:0.1.0-dev10")
implementation("androidx.ui:ui-material:0.1.0-dev10")
//..
buildFeatures {
    compose = true
}

The project is also configured to use java 8

Answer 1

https://developer.android.com/jetpack/compose/setup do not forget the snippets

 composeOptions {
        kotlinCompilerVersion '1.4.21'
        kotlinCompilerExtensionVersion '1.0.0-alpha10'
 }

Answer 2

You also need to add

    composeOptions {
        kotlinCompilerVersion "1.3.70-dev-withExperimentalGoogleExtensions-20200424"
        kotlinCompilerExtensionVersion "0.1.0-dev10"
    }

to your app build.gradle

Answer 3

In my case it was because the compose plugin was installed but the library dependencies were not yet added to my commonMain source set.

kotlin {
    sourceSets {
        val commonMain by getting {
            dependencies {
                api(compose.runtime)
                api(compose.foundation)
                api(compose.material)
            }
        }
    }
}