Support Scala3 .tasty files

timothyklim · copybara-github · commit 1489f0f4cae3 · 2020-12-07T05:03:15.000-08:00
**ijar** tool support Kotlin modules by [not stripped out](bazelbuild@088d8de) files in `META-INF/*.kotlin_module`. This PR add support for new Scala 3 (and Scala 2.13.4+) [TASTy](https://dotty.epfl.ch/docs/reference/metaprogramming/toc.html) format to have ability to use Scala 3 modules. Closes bazelbuild#12529. PiperOrigin-RevId: 346068234
diff --git a/third_party/ijar/ijar.cc b/third_party/ijar/ijar.cc
@@ -37,6 +37,8 @@ const char *CLASS_EXTENSION = ".class";
 const size_t CLASS_EXTENSION_LENGTH = strlen(CLASS_EXTENSION);
 const char *KOTLIN_MODULE_EXTENSION = ".kotlin_module";
 const size_t KOTLIN_MODULE_EXTENSION_LENGTH = strlen(KOTLIN_MODULE_EXTENSION);
+const char *SCALA_TASTY_EXTENSION = ".tasty";
+const size_t SCALA_TASTY_EXTENSION_LENGTH = strlen(SCALA_TASTY_EXTENSION);
 
 const char *MANIFEST_DIR_PATH = "META-INF/";
 const size_t MANIFEST_DIR_PATH_LENGTH = strlen(MANIFEST_DIR_PATH);
@@ -101,9 +103,15 @@ static bool IsKotlinModule(const char *filename, const size_t filename_len) {
                   KOTLIN_MODULE_EXTENSION_LENGTH);
 }
 
+static bool IsScalaTasty(const char *filename, const size_t filename_len) {
+  return EndsWith(filename, filename_len, SCALA_TASTY_EXTENSION,
+                  SCALA_TASTY_EXTENSION_LENGTH);
+}
+
 bool JarStripperProcessor::Accept(const char *filename, const u4 /*attr*/) {
   const size_t filename_len = strlen(filename);
-  if (IsKotlinModule(filename, filename_len)) {
+  if (IsKotlinModule(filename, filename_len) ||
+      IsScalaTasty(filename, filename_len)) {
     return true;
   }
   if (filename_len < CLASS_EXTENSION_LENGTH ||
@@ -129,7 +137,8 @@ void JarStripperProcessor::Process(const char *filename, const u4 /*attr*/,
   if (verbose) {
     fprintf(stderr, "INFO: StripClass: %s\n", filename);
   }
-  if (IsModuleInfo(filename) || IsKotlinModule(filename, strlen(filename))) {
+  if (IsModuleInfo(filename) || IsKotlinModule(filename, strlen(filename)) ||
+      IsScalaTasty(filename, strlen(filename))) {
     u1 *q = builder_->NewFile(filename, 0);
     memcpy(q, data, size);
     builder_->FinishFile(size, /* compress: */ false, /* compute_crc: */ true);
diff --git a/third_party/ijar/test/BUILD b/third_party/ijar/test/BUILD
@@ -267,6 +267,31 @@ genrule(
     tools = ["//third_party/ijar"],
 )
 
+java_binary(
+    name = "GenScalaTasty",
+    testonly = 1,
+    srcs = ["GenScalaTasty.java"],
+    main_class = "GenScalaTasty",
+    deps = ["//third_party:guava"],
+)
+
+genrule(
+    name = "scala_tasty",
+    testonly = 1,
+    outs = ["scala_tasty.jar"],
+    cmd = "$(location :GenScalaTasty) $@",
+    tools = [":GenScalaTasty"],
+)
+
+genrule(
+    name = "scala_tasty-interface",
+    testonly = 1,
+    srcs = [":scala_tasty.jar"],
+    outs = ["scala_tasty-interface.jar"],
+    cmd = "$(location //third_party/ijar) $< $@",
+    tools = ["//third_party/ijar"],
+)
+
 java_test(
     name = "IjarTests",
     size = "small",
@@ -295,6 +320,7 @@ java_test(
         ":liblocal_and_anonymous_lib.jar",
         ":local_and_anonymous-interface.jar",
         ":module_info-interface.jar",
+        ":scala_tasty-interface.jar",
     ],
     tags = ["zip"],
     test_class = "IjarTests",
diff --git a/third_party/ijar/test/GenScalaTasty.java b/third_party/ijar/test/GenScalaTasty.java
@@ -0,0 +1,41 @@
+// Copyright 2020 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.io.ByteStreams;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.jar.JarOutputStream;
+import java.util.zip.ZipEntry;
+
+/** A generator for a jar file containing a .tasty file, and one real class file. */
+public class GenScalaTasty {
+  public static void main(String[] args) throws IOException {
+    try (JarOutputStream jos = new JarOutputStream(Files.newOutputStream(Paths.get(args[0])))) {
+      addEntry(jos, "Bar.tasty");
+      jos.write("hello".getBytes(UTF_8));
+
+      addEntry(jos, "java/lang/String.class");
+      ByteStreams.copy(String.class.getResourceAsStream("/java/lang/String.class"), jos);
+    }
+  }
+
+  private static void addEntry(JarOutputStream jos, String name) throws IOException {
+    ZipEntry ze = new ZipEntry(name);
+    ze.setTime(0);
+    jos.putNextEntry(ze);
+  }
+}
diff --git a/third_party/ijar/test/IjarTests.java b/third_party/ijar/test/IjarTests.java
@@ -248,7 +248,9 @@ static Map<String, byte[]> readJar(String path) throws IOException {
       Enumeration<JarEntry> entries = jf.entries();
       while (entries.hasMoreElements()) {
         JarEntry je = entries.nextElement();
-        if (!je.getName().endsWith(".class") && !je.getName().endsWith(".kotlin_module")) {
+        if (!je.getName().endsWith(".class")
+            && !je.getName().endsWith(".kotlin_module")
+            && !je.getName().endsWith(".tasty")) {
           continue;
         }
         classes.put(je.getName(), ByteStreams.toByteArray(jf.getInputStream(je)));
@@ -291,6 +293,14 @@ public void kotlinModule() throws Exception {
     assertThat(new String(lib.get("META-INF/bar.kotlin_module"), UTF_8)).isEqualTo("hello");
   }
 
+  @Test
+  public void scalaTasty() throws Exception {
+    Map<String, byte[]> lib = readJar("third_party/ijar/test/scala_tasty-interface.jar");
+    assertThat(lib.keySet()).containsExactly("java/lang/String.class", "Bar.tasty");
+    // ijar passes scala tasty files through unmodified
+    assertThat(new String(lib.get("Bar.tasty"), UTF_8)).isEqualTo("hello");
+  }
+
   @Test
   public void testTargetLabel() throws Exception {
     try (JarFile jf =
