[mpp] Mark Kotlin12XMppDeprecation as FATAL

Old MPP plugins are deprecated for a long time. It is time to report
fatal error for such cases.
Our stdlib still and kotlin-test still using them, so we cannot just
completely remove them, but there is a way to suppress this error:
kotlin.internal.mpp12x.deprecation.suppress=true

Code for the old plugins (together with the remaining testsdata)
will be completely removed once stdlib and kotlin-test
migration completed. ETA: ~ 2.0-Mx

#KT-60553 Verification Pending

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

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.gradle.testbase.assertNoDiagnostic
 import org.jetbrains.kotlin.gradle.util.AGPVersion
 import org.jetbrains.kotlin.gradle.util.getFileByName
 import org.jetbrains.kotlin.gradle.util.modify
+import org.jetbrains.kotlin.gradle.util.replaceText
 import org.jetbrains.kotlin.test.util.KtTestUtil
 import org.junit.Test
 import java.io.File
@@ -43,11 +44,29 @@ class MultiplatformGradleIT : BaseGradleIT() {
     fun testMultiplatformCompile() {
         val project = Project("multiplatformProject")
 
+        project.setupWorkingDir()
+
+        // remove the default suppression that was added for all other tests
+        project.projectDir.resolve("gradle.properties").replaceText("kotlin.internal.mpp12x.deprecation.suppress=true", "")
+
         project.build("build") {
-            assertSuccessful()
+            assertFailed()
 
             assertHasDiagnostic(KotlinToolingDiagnostics.Kotlin12XMppDeprecation)
 
+            assertTasksNotExecuted(
+                ":lib:compileKotlinCommon",
+                ":lib:compileTestKotlinCommon",
+                ":libJvm:compileKotlin",
+                ":libJvm:compileTestKotlin",
+            )
+        }
+
+        project.projectDir.resolve("gradle.properties").appendText("\nkotlin.internal.mpp12x.deprecation.suppress=true")
+        project.build("build") {
+            assertSuccessful()
+
+            assertNoDiagnostic(KotlinToolingDiagnostics.Kotlin12XMppDeprecation)
             assertTasksExecuted(
                 ":lib:compileKotlinCommon",
                 ":lib:compileTestKotlinCommon",
@@ -59,13 +78,6 @@ class MultiplatformGradleIT : BaseGradleIT() {
             assertFileExists("libJvm/build/classes/kotlin/main/foo/PlatformClass.class")
             assertFileExists("libJvm/build/classes/kotlin/test/foo/PlatformTest.class")
         }
-
-        project.projectDir.resolve("gradle.properties").appendText("\nkotlin.internal.mpp12x.deprecation.suppress=true")
-        project.build {
-            assertSuccessful()
-
-            assertNoDiagnostic(KotlinToolingDiagnostics.Kotlin12XMppDeprecation)
-        }
     }
 
     @Test

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kapt2/mpp-kapt-presence/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin2JsIrDtsGeneration/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin2JsModuleKind/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin2JsNoOutputFileProject/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin2JsProject/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin2JsProjectWithTests/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

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

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

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

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/new-mpp-lib-and-app/sample-old-style-app/gradle.properties

@@ -0,0 +1 @@
+kotlin.internal.mpp12x.deprecation.suppress=true

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/diagnostics/KotlinToolingDiagnostics.kt

@@ -207,10 +207,10 @@ object KotlinToolingDiagnostics {
         )
     }
 
-    object Kotlin12XMppDeprecation : ToolingDiagnosticFactory(WARNING) {
+    object Kotlin12XMppDeprecation : ToolingDiagnosticFactory(FATAL) {
         operator fun invoke() = build(
             """
-            The 'org.jetbrains.kotlin.platform.*' plugins are deprecated and are no longer available since Kotlin 1.4.
+            The 'org.jetbrains.kotlin.platform.*' plugins are no longer available.
             Please migrate the project to the 'org.jetbrains.kotlin.multiplatform' plugin.
             See: https://kotlinlang.org/docs/reference/building-mpp-with-gradle.html
             """.trimIndent()