Gradle, js, external declarations: read flags from properties

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinProperties.kt

@@ -140,6 +140,18 @@ internal class PropertiesProvider(private val project: Project) {
     val nativeJvmArgs: String?
         get() = propertyWithDeprecatedVariant("kotlin.native.jvmArgs", "org.jetbrains.kotlin.native.jvmArgs")
 
+    /**
+     * Generate kotlin/js external declarations from all .d.ts files found in npm modules
+     */
+    val jsGenerateExternals: Boolean?
+        get() = booleanProperty("kotlin.js.experimental.generateKotlinExternals")
+
+    /**
+     * Automaticaly discover external .d.ts declarations
+     */
+    val jsDiscoverTypes: Boolean?
+        get() = booleanProperty("kotlin.js.experimental.discoverTypes")
+
     private fun propertyWithDeprecatedVariant(propName: String, deprecatedPropName: String): String? {
         val deprecatedProperty = property(deprecatedPropName)
         if (deprecatedProperty != null) {

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/nodejs/NodeJsRootExtension.kt

@@ -3,6 +3,7 @@ package org.jetbrains.kotlin.gradle.targets.js.nodejs
 import org.gradle.api.Project
 import org.jetbrains.kotlin.gradle.internal.isInIdeaSync
 import org.jetbrains.kotlin.gradle.logging.kotlinInfo
+import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJsCompilation
 import org.jetbrains.kotlin.gradle.targets.js.NpmVersions
 import org.jetbrains.kotlin.gradle.targets.js.npm.KotlinNpmResolutionManager
@@ -36,9 +37,14 @@ open class NodeJsRootExtension(val rootProject: Project) {
 
     var packageManager: NpmApi = Yarn
 
-    class Experimental {
-        var generateKotlinExternals: Boolean = false
-        var discoverTypes: Boolean = false
+    private val projectProperties = PropertiesProvider(rootProject)
+
+    inner class Experimental {
+        val generateKotlinExternals: Boolean
+            get() = projectProperties.jsGenerateExternals == true
+
+        val discoverTypes: Boolean
+            get() = projectProperties.jsDiscoverTypes == true
     }
 
     val experimental = Experimental()