Add nightly compilation tests for Scala 2 library TASTy (#18892)

This adds a new CI test for the Scala 2 library TASTy configuration. We
enable all `testCompilation` tests except a few that are blacklisted and
need to be fixed at some point. This test only triggers on nightly
builds or with the `[test_scala2_library_tasty]` tag. We also keep the
current set of tests on every PR.

[test_scala2_library_tasty]

Author: bishabosha

.github/workflows/ci.yaml

@@ -143,9 +143,51 @@ jobs:
         run: |
           ./project/scripts/sbt ";sjsSandbox/run ;sjsSandbox/test ;sjsJUnitTests/test ;set sjsJUnitTests/scalaJSLinkerConfig ~= switchToESModules ;sjsJUnitTests/test ;sjsCompilerTests/test"
 
-      - name: Test with Scala 2 library TASTy
+      - name: Test with Scala 2 library TASTy (fast)
         run: ./project/scripts/sbt ";set ThisBuild/Build.useScala2LibraryTasty := true ;scala3-bootstrapped/testCompilation i5; scala3-bootstrapped/testCompilation tests/run/typelevel-peano.scala" # only test a subset of test to avoid doubling the CI execution time
 
+  test_scala2_library_tasty:
+    runs-on: [self-hosted, Linux]
+    container:
+      image: lampepfl/dotty:2021-03-22
+      options: --cpu-shares 4096
+      volumes:
+        - ${{ github.workspace }}/../../cache/sbt:/root/.sbt
+        - ${{ github.workspace }}/../../cache/ivy:/root/.ivy2/cache
+        - ${{ github.workspace }}/../../cache/general:/root/.cache
+    if: "github.event_name == 'schedule' && github.repository == 'lampepfl/dotty'
+         || (
+           github.event_name == 'pull_request'
+           && contains(github.event.pull_request.body, '[test_scala2_library_tasty]')
+         )
+         || (
+           github.event_name == 'workflow_dispatch'
+           && github.repository == 'lampepfl/dotty'
+         )"
+
+    steps:
+      - name: Set JDK 16 as default
+        run: echo "/usr/lib/jvm/java-16-openjdk-amd64/bin" >> $GITHUB_PATH
+
+      - name: Reset existing repo
+        run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true
+
+      - name: Checkout cleanup script
+        uses: actions/checkout@v3
+
+      - name: Cleanup
+        run: .github/workflows/cleanup.sh
+
+      - name: Git Checkout
+        uses: actions/checkout@v3
+
+      - name: Add SBT proxy repositories
+        run: cp -vf .github/workflows/repositories /root/.sbt/ ; true
+
+      - name: Test with Scala 2 library TASTy
+        run: ./project/scripts/sbt ";set ThisBuild/Build.useScala2LibraryTasty := true ;scala3-bootstrapped/testCompilation"
+
+
   test_windows_fast:
     runs-on: [self-hosted, Windows]
     if: "(

compiler/test/dotc/neg-init-global-scala2-library-tasty.blacklist

@@ -0,0 +1,6 @@
+## See #18882
+patmat.scala
+t9312.scala
+unapplySeq-implicit-arg.scala
+unapplySeq-implicit-arg2.scala
+unapplySeq-implicit-arg3.scala

compiler/test/dotc/neg-scala2-library-tasty.blacklist

@@ -0,0 +1,2 @@
+i8752.scala
+f-interpolator-neg.scala # Additional: A pure expression does nothing in statement position

compiler/test/dotc/patmat-exhaustivity-scala2-library-tasty.blacklist

@@ -0,0 +1,4 @@
+t7746.scala # order of exhaustivity suggestions differs
+t4408.scala # order of exhaustivity suggestions differs
+patmat-ortype.scala # order of exhaustivity suggestions differs
+i13003.scala # order of exhaustivity suggestions differs

compiler/test/dotc/pos-init-global-scala2-library-tasty.blacklist

@@ -0,0 +1,5 @@
+## See #18882
+patmat.scala
+patmat-interpolator.scala
+unapplySeq-implicit-arg-pos.scala
+global-cycle11.scala

compiler/test/dotc/run-macros-scala2-library-tasty.blacklist

@@ -0,0 +1,4 @@
+# Checkfile differences for equivalent type
+tasty-extractors-1
+tasty-extractors-2
+tasty-extractors-types

compiler/test/dotty/Properties.scala

@@ -85,6 +85,9 @@ object Properties {
   /** scala-library TASTy jar */
   def scalaLibraryTasty: Option[String] = sys.props.get("dotty.tests.tasties.scalaLibrary")
 
+  /** If we are using the scala-library TASTy jar */
+  def usingScalaLibraryTasty: Boolean = scalaLibraryTasty.isDefined
+
   /** scala-asm jar */
   def scalaAsm: String = sys.props("dotty.tests.classes.scalaAsm")
 

compiler/test/dotty/tools/TestSources.scala

@@ -6,6 +6,7 @@ import java.io.File
 import java.nio.file._
 
 import scala.jdk.CollectionConverters._
+import dotty.Properties
 
 object TestSources {
 
@@ -16,25 +17,52 @@ object TestSources {
   def posTestRecheckExcludesFile: String = "compiler/test/dotc/pos-test-recheck.excludes"
   def posLazyValsAllowlistFile: String = "compiler/test/dotc/pos-lazy-vals-tests.allowlist"
   def posLintingAllowlistFile: String = "compiler/test/dotc/pos-linting.allowlist"
+  def posInitGlobalScala2LibraryTastyBlacklistFile: String = "compiler/test/dotc/pos-init-global-scala2-library-tasty.blacklist"
 
   def posFromTastyBlacklisted: List[String] = loadList(posFromTastyBlacklistFile)
   def posTestPicklingBlacklisted: List[String] = loadList(posTestPicklingBlacklistFile)
   def posTestRecheckExcluded: List[String] = loadList(posTestRecheckExcludesFile)
   def posLazyValsAllowlist: List[String] = loadList(posLazyValsAllowlistFile)
   def posLintingAllowlist: List[String] = loadList(posLintingAllowlistFile)
+  def posInitGlobalScala2LibraryTastyBlacklisted: List[String] =
+    if Properties.usingScalaLibraryTasty then loadList(posInitGlobalScala2LibraryTastyBlacklistFile)
+    else Nil
 
   // run tests lists
 
   def runFromTastyBlacklistFile: String = "compiler/test/dotc/run-from-tasty.blacklist"
   def runTestPicklingBlacklistFile: String = "compiler/test/dotc/run-test-pickling.blacklist"
   def runTestRecheckExcludesFile: String = "compiler/test/dotc/run-test-recheck.excludes"
   def runLazyValsAllowlistFile: String = "compiler/test/dotc/run-lazy-vals-tests.allowlist"
-
+  def runMacrosScala2LibraryTastyBlacklistFile: String = "compiler/test/dotc/run-macros-scala2-library-tasty.blacklist"
 
   def runFromTastyBlacklisted: List[String] = loadList(runFromTastyBlacklistFile)
   def runTestPicklingBlacklisted: List[String] = loadList(runTestPicklingBlacklistFile)
   def runTestRecheckExcluded: List[String] = loadList(runTestRecheckExcludesFile)
   def runLazyValsAllowlist: List[String] = loadList(runLazyValsAllowlistFile)
+  def runMacrosScala2LibraryTastyBlacklisted: List[String] =
+    if Properties.usingScalaLibraryTasty then loadList(runMacrosScala2LibraryTastyBlacklistFile)
+    else Nil
+
+  // neg tests lists
+
+  def negScala2LibraryTastyBlacklistFile: String = "compiler/test/dotc/neg-scala2-library-tasty.blacklist"
+  def negInitGlobalScala2LibraryTastyBlacklistFile: String = "compiler/test/dotc/neg-init-global-scala2-library-tasty.blacklist"
+
+  def negScala2LibraryTastyBlacklisted: List[String] =
+    if Properties.usingScalaLibraryTasty then loadList(negScala2LibraryTastyBlacklistFile)
+    else Nil
+  def negInitGlobalScala2LibraryTastyBlacklisted: List[String] =
+    if Properties.usingScalaLibraryTasty then loadList(negInitGlobalScala2LibraryTastyBlacklistFile)
+    else Nil
+
+  // patmat tests lists
+
+  def patmatExhaustivityScala2LibraryTastyBlacklistFile: String = "compiler/test/dotc/patmat-exhaustivity-scala2-library-tasty.blacklist"
+
+  def patmatExhaustivityScala2LibraryTastyBlacklisted: List[String] =
+    if Properties.usingScalaLibraryTasty then loadList(patmatExhaustivityScala2LibraryTastyBlacklistFile)
+    else Nil
 
   // load lists
 

compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala

@@ -120,7 +120,7 @@ class BootstrappedOnlyCompilationTests {
 
   @Test def runMacros: Unit = {
     implicit val testGroup: TestGroup = TestGroup("runMacros")
-    compileFilesInDir("tests/run-macros", defaultOptions.and("-Xcheck-macros"))
+    compileFilesInDir("tests/run-macros", defaultOptions.and("-Xcheck-macros"), FileFilter.exclude(TestSources.runMacrosScala2LibraryTastyBlacklisted))
       .checkRuns()
   }
 

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -44,7 +44,10 @@ class CompilationTests {
       // Run tests for legacy lazy vals
       compileFilesInDir("tests/pos", defaultOptions.and("-Ysafe-init", "-Ylegacy-lazy-vals", "-Ycheck-constraint-deps"), FileFilter.include(TestSources.posLazyValsAllowlist)),
       compileDir("tests/pos-special/java-param-names", defaultOptions.withJavacOnlyOptions("-parameters")),
-      compileDir("tests/pos-special/stdlib", allowDeepSubtypes),
+    ) ::: (
+      // FIXME: This fails due to a bug involving self types and capture checking
+      if Properties.usingScalaLibraryTasty then Nil
+      else List(compileDir("tests/pos-special/stdlib", allowDeepSubtypes))
     )
 
     if scala.util.Properties.isJavaAtLeast("16") then
@@ -130,7 +133,7 @@ class CompilationTests {
   @Test def negAll: Unit = {
     implicit val testGroup: TestGroup = TestGroup("compileNeg")
     aggregateTests(
-      compileFilesInDir("tests/neg", defaultOptions),
+      compileFilesInDir("tests/neg", defaultOptions, FileFilter.exclude(TestSources.negScala2LibraryTastyBlacklisted)),
       compileFilesInDir("tests/neg-deep-subtype", allowDeepSubtypes),
       compileFilesInDir("tests/neg-custom-args/captures", defaultOptions.and("-language:experimental.captureChecking")),
       compileFile("tests/neg-custom-args/sourcepath/outer/nested/Test1.scala", defaultOptions.and("-sourcepath", "tests/neg-custom-args/sourcepath")),
@@ -213,8 +216,8 @@ class CompilationTests {
   @Test def checkInitGlobal: Unit = {
     implicit val testGroup: TestGroup = TestGroup("checkInitGlobal")
     val options = defaultOptions.and("-Ysafe-init-global", "-Xfatal-warnings")
-    compileFilesInDir("tests/init-global/neg", options).checkExpectedErrors()
-    compileFilesInDir("tests/init-global/pos", options).checkCompile()
+    compileFilesInDir("tests/init-global/neg", options, FileFilter.exclude(TestSources.negInitGlobalScala2LibraryTastyBlacklisted)).checkExpectedErrors()
+    compileFilesInDir("tests/init-global/pos", options, FileFilter.exclude(TestSources.posInitGlobalScala2LibraryTastyBlacklisted)).checkCompile()
   }
 
   // initialization tests

compiler/test/dotty/tools/dotc/coverage/CoverageTests.scala

@@ -3,6 +3,7 @@ package dotty.tools.dotc.coverage
 import org.junit.Test
 import org.junit.AfterClass
 import org.junit.Assert.*
+import org.junit.Assume.*
 import org.junit.experimental.categories.Category
 import dotty.{BootstrappedOnlyTests, Properties}
 import dotty.tools.vulpix.*
@@ -28,10 +29,18 @@ class CoverageTests:
 
   @Test
   def checkCoverageStatements(): Unit =
+    assumeFalse(
+      "FIXME: test output differs when using Scala 2 library TASTy",
+      Properties.usingScalaLibraryTasty
+    )
     checkCoverageIn(rootSrc.resolve("pos"), false)
 
   @Test
   def checkInstrumentedRuns(): Unit =
+    assumeFalse(
+      "FIXME: test output differs when using Scala 2 library TASTy",
+      Properties.usingScalaLibraryTasty
+    )
     checkCoverageIn(rootSrc.resolve("run"), true)
 
   def checkCoverageIn(dir: Path, run: Boolean)(using TestGroup): Unit =

compiler/test/dotty/tools/dotc/transform/PatmatExhaustivityTest.scala

@@ -63,12 +63,14 @@ class PatmatExhaustivityTest {
 
   @Test
   def patmatExhaustivity: Unit = {
+    val blacklisted = TestSources.patmatExhaustivityScala2LibraryTastyBlacklisted.toSet
     val res = Directory(testsDir).list.toList
       .filter(f => f.extension == "scala" || f.isDirectory)
       .filter { f =>
         val path = if f.isDirectory then f.path + "/" else f.path
         Properties.testsFilter.isEmpty || Properties.testsFilter.exists(path.contains)
       }
+      .filterNot(f => blacklisted.contains(f.name))
       .map(f => if f.isDirectory then compileDir(f.jpath) else compileFile(f.jpath))
 
     val failed = res.filter(!_)

docs/_docs/contributing/sending-in-a-pr.md

@@ -125,10 +125,11 @@ Below are commonly used ones:
 Depending on what your PR is addressing, sometimes it doesn't make sense to run
 parts of the CI that usually ony runs on nightly builds.
 
-|---------------------------|----------------------------------------------------|
-| `[test_java8]`            | Execute unit tests on Java 8                       |
-| `[test_windows_full]`     | Execute unit tests on Windows                      |
-| `[test_non_bootstrapped]` | Execute unit tests using non-bootstrapped compiler |
+|-------------------------------|---------------------------------------------------------------------------|
+| `[test_java8]`                | Execute unit tests on Java 8                                              |
+| `[test_windows_full]`         | Execute unit tests on Windows                                             |
+| `[test_non_bootstrapped]`     | Execute unit tests using non-bootstrapped compiler                        |
+| `[test_scala2_library_tasty]` | Execute unit tests using bootstrapped-compiler with Scala 2 library TASTy |
 
 ### 7: Create your PR!
 

project/Build.scala

@@ -176,7 +176,7 @@ object Build {
   // Use the TASTy jar from `scala2-library-tasty` in the classpath
   // This only works with `scala3-bootstrapped/scalac` and tests in `scala3-bootstrapped`
   //
-  // Enable in SBT with: set ThisBuild/Build.useScala2LibraryTasty := true
+  // Enable in SBT with: `set ThisBuild/Build.useScala2LibraryTasty := true`
   val useScala2LibraryTasty = settingKey[Boolean]("Use the TASTy jar from `scala2-library-tasty` in the classpath")
 
   // Used to compile files similar to ./bin/scalac script