Scan Kotlin constants for JavaPsiFacade

so that constants in light classes can be resolved by JavaPsiFacade.

compiler-plugin/src/main/kotlin/com/google/devtools/ksp/KotlinSymbolProcessingExtension.kt

@@ -31,8 +31,14 @@ import com.google.devtools.ksp.processing.impl.NativePlatformInfoImpl
 import com.google.devtools.ksp.processing.impl.ResolverImpl
 import com.google.devtools.ksp.processing.impl.UnknownPlatformInfoImpl
 import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSDeclarationContainer
 import com.google.devtools.ksp.symbol.KSFile
+import com.google.devtools.ksp.symbol.KSPropertyDeclaration
+import com.google.devtools.ksp.symbol.KSVisitorVoid
+import com.google.devtools.ksp.symbol.Modifier
 import com.google.devtools.ksp.symbol.Origin
+import com.google.devtools.ksp.symbol.Visibility
 import com.google.devtools.ksp.symbol.impl.java.KSFileJavaImpl
 import com.google.devtools.ksp.symbol.impl.kotlin.KSFileImpl
 import com.intellij.openapi.project.Project
@@ -198,6 +204,42 @@ abstract class AbstractKotlinSymbolProcessingExtension(
             newFiles, deferredSymbols, bindingTrace, project, componentProvider, incrementalContext, options
         )
 
+        if (!initialized) {
+            // Visit constants so that JavaPsiFacade knows them.
+            // The annotation visitor in ResolverImpl covered newFiles already.
+            // Skip private and local members, which are not visible to Java files.
+            ksFiles.filterIsInstance<KSFileImpl>().filter { it !in dirtyFiles }.forEach {
+                try {
+                    it.accept(
+                        object : KSVisitorVoid() {
+                            private fun visitDeclarationContainer(container: KSDeclarationContainer) {
+                                container.declarations.filterNot {
+                                    it.getVisibility() == Visibility.PRIVATE
+                                }.forEach {
+                                    it.accept(this, Unit)
+                                }
+                            }
+
+                            override fun visitFile(file: KSFile, data: Unit) =
+                                visitDeclarationContainer(file)
+
+                            override fun visitClassDeclaration(classDeclaration: KSClassDeclaration, data: Unit) =
+                                visitDeclarationContainer(classDeclaration)
+
+                            override fun visitPropertyDeclaration(property: KSPropertyDeclaration, data: Unit) {
+                                if (property.modifiers.contains(Modifier.CONST)) {
+                                    property.getter // force resolution
+                                }
+                            }
+                        },
+                        Unit
+                    )
+                } catch (_: Exception) {
+                    // Do nothing.
+                }
+            }
+        }
+
         val providers = loadProviders()
         if (!initialized) {
             codeGenerator = CodeGeneratorImpl(

integration-tests/src/test/kotlin/com/google/devtools/ksp/test/KotlinConstsInJavaIT.kt

@@ -0,0 +1,42 @@
+package com.google.devtools.ksp.test
+
+import org.gradle.testkit.runner.BuildResult
+import org.gradle.testkit.runner.GradleRunner
+import org.gradle.testkit.runner.TaskOutcome
+import org.junit.Assert
+import org.junit.Assume
+import org.junit.Rule
+import org.junit.Test
+import java.io.File
+
+class KotlinConstsInJavaIT {
+    @Rule
+    @JvmField
+    val project: TemporaryTestProject = TemporaryTestProject("kotlin-consts-in-java")
+
+    private fun GradleRunner.buildAndCheck(vararg args: String, extraCheck: (BuildResult) -> Unit = {}) =
+        buildAndCheckOutcome(*args, outcome = TaskOutcome.SUCCESS, extraCheck = extraCheck)
+
+    private fun GradleRunner.buildAndCheckOutcome(
+        vararg args: String,
+        outcome: TaskOutcome,
+        extraCheck: (BuildResult) -> Unit = {}
+    ) {
+        val result = this.withArguments(*args).build()
+
+        Assert.assertEquals(outcome, result.task(":workload:kspKotlin")?.outcome)
+
+        extraCheck(result)
+    }
+
+    @Test
+    fun testKotlinConstsInJava() {
+        // FIXME: `clean` fails to delete files on windows.
+        Assume.assumeFalse(System.getProperty("os.name").startsWith("Windows", ignoreCase = true))
+        val gradleRunner = GradleRunner.create().withProjectDir(project.root).withDebug(true)
+        gradleRunner.buildAndCheck(":workload:kspKotlin")
+
+        File(project.root, "workload/src/main/java/com/example/JavaClass.java").appendText("\n")
+        gradleRunner.buildAndCheck(":workload:kspKotlin")
+    }
+}

integration-tests/src/test/resources/kotlin-consts-in-java/build.gradle.kts

@@ -0,0 +1,8 @@
+plugins {
+    kotlin("jvm")
+}
+
+repositories {
+    mavenCentral()
+    maven("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/bootstrap/")
+}

integration-tests/src/test/resources/kotlin-consts-in-java/settings.gradle.kts

@@ -0,0 +1,19 @@
+pluginManagement {
+    val kotlinVersion: String by settings
+    val kspVersion: String by settings
+    val testRepo: String by settings
+    plugins {
+        id("com.google.devtools.ksp") version kspVersion
+        kotlin("jvm") version kotlinVersion
+    }
+    repositories {
+        maven(testRepo)
+        gradlePluginPortal()
+        maven("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/bootstrap/")
+    }
+}
+
+rootProject.name = "playground"
+
+include(":workload")
+include(":test-processor")

integration-tests/src/test/resources/kotlin-consts-in-java/test-processor/build.gradle.kts

@@ -0,0 +1,24 @@
+val kspVersion: String by project
+val testRepo: String by project
+
+plugins {
+    kotlin("jvm")
+}
+
+group = "com.example"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    maven(testRepo)
+    mavenCentral()
+    maven("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/bootstrap/")
+}
+
+dependencies {
+    implementation(kotlin("stdlib"))
+    implementation("com.google.devtools.ksp:symbol-processing-api:$kspVersion")
+}
+
+sourceSets.main {
+    java.srcDirs("src/main/kotlin")
+}

integration-tests/src/test/resources/kotlin-consts-in-java/test-processor/src/main/kotlin/TestProcessor.kt

@@ -0,0 +1,27 @@
+import com.google.devtools.ksp.processing.*
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSFunctionDeclaration
+
+class TestProcessor(
+    private val codeGenerator: CodeGenerator,
+    private val options: Map<String, String>,
+    private val logger: KSPLogger
+) : SymbolProcessor {
+    override fun process(resolver: Resolver): List<KSAnnotated> {
+        resolver
+            .getSymbolsWithAnnotation("com.example.ann.MyAnn")
+            .filterIsInstance<KSFunctionDeclaration>()
+            .forEach { func ->
+                val arg = func.annotations.first().arguments.first().value.toString()
+                if (!arg.startsWith("REPLACE"))
+                    throw IllegalStateException(arg)
+            }
+
+        return emptyList()
+    }
+}
+
+class TestProcessorProvider : SymbolProcessorProvider {
+    override fun create(environment: SymbolProcessorEnvironment): SymbolProcessor =
+        TestProcessor(environment.codeGenerator, environment.options, environment.logger)
+}

integration-tests/src/test/resources/kotlin-consts-in-java/test-processor/src/main/resources/META-INF/services/com.google.devtools.ksp.processing.SymbolProcessorProvider

@@ -0,0 +1 @@
+TestProcessorProvider

integration-tests/src/test/resources/kotlin-consts-in-java/workload/build.gradle.kts

@@ -0,0 +1,20 @@
+val testRepo: String by project
+
+plugins {
+    id("com.google.devtools.ksp")
+    kotlin("jvm")
+}
+
+version = "1.0-SNAPSHOT"
+
+repositories {
+    maven(testRepo)
+    mavenCentral()
+    maven("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/bootstrap/")
+}
+
+dependencies {
+    implementation(kotlin("stdlib"))
+    implementation(project(":test-processor"))
+    ksp(project(":test-processor"))
+}

integration-tests/src/test/resources/kotlin-consts-in-java/workload/src/main/java/com/example/JavaClass.java

@@ -0,0 +1,9 @@
+package com.example;
+
+import com.example.ann.MyAnn;
+
+public class JavaClass {
+    @MyAnn(KotlinConsts.ACTION)
+    public void f() {
+    }
+}

integration-tests/src/test/resources/kotlin-consts-in-java/workload/src/main/java/com/example/KotlinConsts.kt

@@ -0,0 +1,8 @@
+package com.example
+
+class KotlinConsts {
+    companion object {
+        const val ACTION = "REPLACE"
+        const val ACTION2 = "REPLACE"
+    }
+}

integration-tests/src/test/resources/kotlin-consts-in-java/workload/src/main/java/com/example/ann/MyAnn.kt

@@ -0,0 +1,3 @@
+package com.example.ann
+
+annotation class MyAnn(val value: String)