From 591bf5eb1a210eb3f149874ae7f3fc029e6a0367 Mon Sep 17 00:00:00 2001
From: Ting-Yuan Huang <laszio@google.com>
Date: Tue, 21 Nov 2023 16:03:32 -0800
Subject: [PATCH] Turn off -progressive when downgrading from K2

Progressive mode should always be used with latest language version.
---
 .../google/devtools/ksp/gradle/KspSubplugin.kt | 13 +++++++++++++
 .../google/devtools/ksp/test/PlaygroundIT.kt   | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/KspSubplugin.kt b/gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/KspSubplugin.kt
index 2b83563656..6d30c5088c 100644
--- a/gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/KspSubplugin.kt
+++ b/gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/KspSubplugin.kt
@@ -366,6 +366,7 @@ class KspGradleSubplugin @Inject internal constructor(private val registry: Tool
         fun configureLanguageVersion(kspTask: KotlinCompilationTask<*>) {
             kspTask.compilerOptions.useK2.value(false)
             val languageVersion = kotlinCompilation.compilerOptions.options.languageVersion
+            val progressiveMode = kotlinCompilation.compilerOptions.options.progressiveMode
             kspTask.compilerOptions.languageVersion.value(
                 project.provider {
                     languageVersion.orNull?.let { version ->
@@ -377,6 +378,18 @@ class KspGradleSubplugin @Inject internal constructor(private val registry: Tool
                     } ?: KotlinVersion.KOTLIN_1_9
                 }
             )
+
+            // Turn off progressive mode if we need to downgrade language version.
+            kspTask.compilerOptions.progressiveMode.value(
+                project.provider {
+                    val compileLangVer = languageVersion.orNull ?: KotlinVersion.DEFAULT
+                    if (compileLangVer >= KotlinVersion.KOTLIN_2_0) {
+                        false
+                    } else {
+                        progressiveMode.orNull
+                    }
+                }
+            )
         }
 
         val isIncremental = project.findProperty("ksp.incremental")?.toString()?.toBoolean() ?: true
diff --git a/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/PlaygroundIT.kt b/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/PlaygroundIT.kt
index b885c25ebe..2079ac1bff 100644
--- a/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/PlaygroundIT.kt
+++ b/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/PlaygroundIT.kt
@@ -361,6 +361,24 @@ class PlaygroundIT(val useKSP2: Boolean) {
         project.restore(properties.path)
     }
 
+    @Test
+    fun testProgressiveMode() {
+        val buildFile = File(project.root, "workload/build.gradle.kts")
+        buildFile.appendText(
+            """
+            kotlin {
+                compilerOptions {
+                    allWarningsAsErrors.value(true)
+                    progressiveMode.value(true)
+               }
+            }
+            """.trimIndent()
+        )
+        val gradleRunner = GradleRunner.create().withProjectDir(project.root).withGradleVersion("8.0")
+        gradleRunner.withArguments("clean", "build").build()
+        project.restore(buildFile.path)
+    }
+
     companion object {
         @JvmStatic
         @Parameterized.Parameters(name = "KSP2={0}")