Make detekt less noisy

detekt-core/src/main/kotlin/io/gitlab/arturbosch/detekt/core/ProcessingSettings.kt

@@ -32,7 +32,7 @@ class ProcessingSettings(
     Closeable,
     LoggingAware by LoggingFacade(spec.loggingSpec),
     PropertiesAware by PropertiesFacade(),
-    EnvironmentAware by EnvironmentFacade(spec.projectSpec, spec.compilerSpec),
+    EnvironmentAware by EnvironmentFacade(spec.projectSpec, spec.compilerSpec, spec.loggingSpec),
     ClassloaderAware by ExtensionFacade(spec.extensionsSpec.plugins),
     SetupContext {
 

detekt-core/src/main/kotlin/io/gitlab/arturbosch/detekt/core/settings/EnvironmentAware.kt

@@ -3,6 +3,7 @@ package io.gitlab.arturbosch.detekt.core.settings
 import io.github.detekt.parser.createCompilerConfiguration
 import io.github.detekt.parser.createKotlinCoreEnvironment
 import io.github.detekt.tooling.api.spec.CompilerSpec
+import io.github.detekt.tooling.api.spec.LoggingSpec
 import io.github.detekt.tooling.api.spec.ProjectSpec
 import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
 import org.jetbrains.kotlin.com.intellij.openapi.Disposable
@@ -11,6 +12,8 @@ import org.jetbrains.kotlin.config.JvmTarget
 import org.jetbrains.kotlin.config.LanguageVersion
 import java.io.Closeable
 import java.io.File
+import java.io.OutputStream
+import java.io.PrintStream
 
 interface EnvironmentAware {
 
@@ -21,7 +24,8 @@ interface EnvironmentAware {
 
 internal class EnvironmentFacade(
     private val projectSpec: ProjectSpec,
-    private val compilerSpec: CompilerSpec
+    private val compilerSpec: CompilerSpec,
+    private val loggingSpec: LoggingSpec,
 ) : AutoCloseable, Closeable, EnvironmentAware {
 
     override val disposable: Disposable = Disposer.newDisposable()
@@ -36,7 +40,11 @@ internal class EnvironmentFacade(
             compilerSpec.parseJvmTarget(),
             compilerSpec.jdkHome,
         )
-        createKotlinCoreEnvironment(compilerConfiguration, disposable)
+        createKotlinCoreEnvironment(
+            compilerConfiguration,
+            disposable,
+            if (loggingSpec.debug) loggingSpec.errorChannel.asPrintStream() else NullPrintStream,
+        )
     }
 
     override fun close() {
@@ -61,3 +69,26 @@ internal fun CompilerSpec.parseJvmTarget(): JvmTarget {
             " must be one of ${JvmTarget.values().map(JvmTarget::description)}"
     }
 }
+
+private object NullPrintStream : PrintStream(
+    object : OutputStream() {
+        override fun write(b: Int) {
+            // no-op
+        }
+    }
+)
+
+private fun Appendable.asPrintStream(): PrintStream {
+    val appendable = this
+    return if (appendable is PrintStream) {
+        appendable
+    } else {
+        PrintStream(
+            object : OutputStream() {
+                override fun write(b: Int) {
+                    appendable.append(b.toChar())
+                }
+            }
+        )
+    }
+}

detekt-parser/src/main/kotlin/io/github/detekt/parser/KotlinEnvironmentUtils.kt

@@ -23,22 +23,39 @@ import org.jetbrains.kotlin.config.LanguageVersion
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.config.LanguageVersionSettingsImpl
 import java.io.File
+import java.io.PrintStream
 import java.net.URLClassLoader
 import java.nio.file.Path
 
 /**
  * Creates an environment instance which can be used to compile source code to KtFile's.
  * This environment also allows to modify the resulting AST files.
  */
+@Deprecated(
+    "You should pass a printStream",
+    ReplaceWith("createKotlinCoreEnvironment(configuration, disposable, System.err)")
+)
 fun createKotlinCoreEnvironment(
     configuration: CompilerConfiguration = CompilerConfiguration(),
     disposable: Disposable = Disposer.newDisposable()
+): KotlinCoreEnvironment {
+    return createKotlinCoreEnvironment(configuration, disposable, System.err)
+}
+
+/**
+ * Creates an environment instance which can be used to compile source code to KtFile's.
+ * This environment also allows to modify the resulting AST files.
+ */
+fun createKotlinCoreEnvironment(
+    configuration: CompilerConfiguration = CompilerConfiguration(),
+    disposable: Disposable = Disposer.newDisposable(),
+    printStream: PrintStream,
 ): KotlinCoreEnvironment {
     // https://github.com/JetBrains/kotlin/commit/2568804eaa2c8f6b10b735777218c81af62919c1
     setIdeaIoUseFallback()
     configuration.put(
         CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY,
-        PrintingMessageCollector(System.err, MessageRenderer.PLAIN_FULL_PATHS, false)
+        PrintingMessageCollector(printStream, MessageRenderer.PLAIN_FULL_PATHS, false)
     )
     configuration.put(CommonConfigurationKeys.MODULE_NAME, "detekt")
 

detekt-parser/src/main/kotlin/io/github/detekt/parser/KtCompiler.kt

@@ -11,7 +11,7 @@ import java.nio.file.Files
 import java.nio.file.Path
 
 open class KtCompiler(
-    protected val environment: KotlinCoreEnvironment = createKotlinCoreEnvironment()
+    protected val environment: KotlinCoreEnvironment = createKotlinCoreEnvironment(printStream = System.err)
 ) {
 
     protected val psiFileFactory = KtPsiFactory(environment.project, markGenerated = false)