Read KotlinCompilerVersion from resource file

Writing build number into a public constant field leads to poor gradle
cache reuse between different builds. Public constant value is a part of
public api and its changes affect inputs of dependent modules.
Extracting build number to resource file allows to ignore it from
runtime classpath which fixes same problem for KotlinCompile tasks

build.gradle.kts

@@ -393,6 +393,7 @@ allprojects {
     normalization {
         runtimeClasspath {
             ignore("META-INF/MANIFEST.MF")
+            ignore("META-INF/compiler.version")
         }
     }
 

core/util.runtime/build.gradle.kts

@@ -1,3 +1,4 @@
+import org.apache.tools.ant.filters.ReplaceTokens
 
 plugins {
     java
@@ -8,6 +9,8 @@ plugins {
 jvmTarget = "1.6"
 javaHome = rootProject.extra["JDK_16"] as String
 
+val kotlinVersion: String by rootProject.extra
+
 dependencies {
     compileOnly(kotlinStdlib())
 }
@@ -22,5 +25,9 @@ tasks.withType<JavaCompile> {
     targetCompatibility = "1.6"
 }
 
-if (project.hasProperty("teamcity"))
-tasks["compileJava"].dependsOn(":prepare:build.version:writeCompilerVersion")
+tasks.named<ProcessResources>("processResources") {
+    inputs.property("compilerVersion", kotlinVersion)
+    filesMatching("META-INF/compiler.version") {
+        filter<ReplaceTokens>("tokens" to mapOf("snapshot" to kotlinVersion))
+    }
+}

core/util.runtime/resources/META-INF/compiler.version

@@ -0,0 +1 @@
+@snapshot@

core/util.runtime/src/org/jetbrains/kotlin/config/KotlinCompilerVersion.java

@@ -18,10 +18,13 @@ package org.jetbrains.kotlin.config;
 
 import org.jetbrains.annotations.Nullable;
 
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
 public class KotlinCompilerVersion {
-    // The value of this constant is generated by the build script
-    // DON'T MODIFY IT
-    public static final String VERSION = "@snapshot@";
+    public static final String VERSION_FILE_PATH = "/META-INF/compiler.version";
+    public static final String VERSION;
 
     // True if the latest stable language version supported by this compiler has not yet been released.
     // Binaries produced by this compiler with that language version (or any future language version) are going to be marked
@@ -45,12 +48,27 @@ public class KotlinCompilerVersion {
      */
     @Nullable
     public static String getVersion() {
-        //noinspection ConstantConditions
         return VERSION.equals("@snapshot@") ? null : VERSION;
     }
 
+    private static String loadKotlinCompilerVersion() throws IOException {
+        BufferedReader versionReader = new BufferedReader(
+                new InputStreamReader(KotlinCompilerVersion.class.getResourceAsStream(VERSION_FILE_PATH)));
+        try {
+            return versionReader.readLine();
+        } finally {
+            versionReader.close();
+        }
+    }
+
     static {
-        //noinspection ConstantConditions
+        try {
+            VERSION = loadKotlinCompilerVersion();
+        }
+        catch (IOException e) {
+            throw new IllegalStateException("Failed to read compiler version from " + VERSION_FILE_PATH);
+        }
+
         if (!VERSION.equals("@snapshot@") && !VERSION.contains("-") && IS_PRE_RELEASE) {
             throw new IllegalStateException(
                     "IS_PRE_RELEASE cannot be true for a compiler without '-' in its version.\n" +

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

@@ -52,12 +52,22 @@ internal fun loadCompilerVersion(compilerClasspath: List<File>): String {
         for (cpFile in compilerClasspath) {
             if (cpFile.isFile && cpFile.extension.toLowerCase() == "jar") {
                 ZipFile(cpFile).use { jar ->
-                    val bytes = jar.getInputStream(jar.getEntry(versionClassFileName)).use { it.readBytes() }
-                    checkVersion(bytes)
+                    val versionFileEntry = jar.getEntry(KotlinCompilerVersion.VERSION_FILE_PATH)
+                    if (versionFileEntry != null) {
+                        result = jar.getInputStream(versionFileEntry).bufferedReader().use { it.readText() }
+                    } else {
+                        val bytes = jar.getInputStream(jar.getEntry(versionClassFileName)).use { it.readBytes() }
+                        checkVersion(bytes)
+                    }
                 }
             } else if (cpFile.isDirectory) {
-                File(cpFile, versionClassFileName).takeIf { it.isFile }?.let {
-                    checkVersion(it.readBytes())
+                val versionFile = File(cpFile, KotlinCompilerVersion.VERSION_FILE_PATH)
+                if (versionFile.isFile) {
+                    result = versionFile.readText()
+                } else {
+                    File(cpFile, versionClassFileName).takeIf { it.isFile }?.let {
+                        checkVersion(it.readBytes())
+                    }
                 }
             }
             if (result != null) break

prepare/build.version/build.gradle.kts

@@ -44,18 +44,6 @@ val writeStdlibVersion by tasks.registering {
     }
 }
 
-val writeCompilerVersion by tasks.registering {
-    val versionFile = rootDir.resolve("core/util.runtime/src/org/jetbrains/kotlin/config/KotlinCompilerVersion.java")
-    inputs.property("version", kotlinVersion)
-    outputs.file(versionFile)
-    doLast {
-        replaceVersion(versionFile, """public static final String VERSION = "([^"]+)"""") {
-            logger.lifecycle("Writing new compiler version: $kotlinVersion")
-            kotlinVersion
-        }
-    }
-}
-
 val writePluginVersion by tasks.registering {
     val versionFile = project(":idea").projectDir.resolve("resources/META-INF/plugin.xml")
     val pluginVersion = rootProject.findProperty("pluginVersion") as String?
@@ -71,5 +59,5 @@ val writePluginVersion by tasks.registering {
 }
 
 val writeVersions by tasks.registering {
-    dependsOn(writeBuildNumber, writeStdlibVersion, writeCompilerVersion)
+    dependsOn(writeBuildNumber, writeStdlibVersion)
 }