[MPP] Fix default parameter value for optimistic commonization in KGP

KT-51332

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/CommonizerHierarchicalIT.kt

@@ -143,6 +143,16 @@ class CommonizerHierarchicalIT : BaseGradleIT() {
         }
     }
 
+    @Test
+    fun `test KT-51332 optimistic commonization`() {
+        with(Project("optimisticCommonization")) {
+            build(":compileCommonMainKotlinMetadata") {
+                assertNotContains("Unresolved reference")
+                assertSuccessful()
+            }
+        }
+    }
+
     private object Os {
         private val os = OperatingSystem.current()
         val canCompileApple get() = os.isMacOsX

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/optimisticCommonization/build.gradle.kts

@@ -0,0 +1,21 @@
+plugins {
+    kotlin("multiplatform")
+}
+
+repositories {
+    mavenCentral()
+    mavenLocal()
+}
+
+kotlin {
+    linuxArm32Hfp("intPlatform") {
+        compilations.get("main").cinterops.create("intPropertyInterop") {
+            header(file("libs/intPlatform.h"))
+        }
+    }
+    linuxX64("longPlatform") {
+        compilations.get("main").cinterops.create("intPropertyInterop") {
+            header(file("libs/longPlatform.h"))
+        }
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/optimisticCommonization/gradle.properties

@@ -0,0 +1 @@
+kotlin.mpp.enableCInteropCommonization=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/optimisticCommonization/libs/intPlatform.h

@@ -0,0 +1 @@
+int unsafeProp;

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/optimisticCommonization/libs/longPlatform.h

@@ -0,0 +1 @@
+long long unsafeProp;

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/optimisticCommonization/src/commonMain/kotlin/common.kt

@@ -0,0 +1,3 @@
+fun testCommon() {
+    intPropertyInterop.unsafeProp
+}

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

@@ -219,7 +219,7 @@ internal class PropertiesProvider private constructor(private val project: Proje
         get() = booleanProperty(KotlinMultiplatformPlugin.STABILITY_NOWARN_FLAG)
 
     val mppEnableOptimisticNumberCommonization: Boolean
-        get() = booleanProperty(KOTLIN_MPP_ENABLE_OPTIMISTIC_NUMBER_COMMONIZATION) ?: false
+        get() = booleanProperty(KOTLIN_MPP_ENABLE_OPTIMISTIC_NUMBER_COMMONIZATION) ?: true
 
     val wasmStabilityNoWarn: Boolean
         get() = booleanProperty("kotlin.wasm.stability.nowarn") ?: false