Add capture checking the compiler as a test (scala#16292)

 - Copy compiler code base into a separate test
 - Adapt code base so that it can be capture checked

Based on scala#16254

Only the last two commits are new:

-
[57527c4](scala@57527c4)
copies the compiler codebase as a separate test.
-
[6dfeaa7](scala@6dfeaa7)
makes the changes so that it passes capture checking.

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

@@ -36,6 +36,12 @@ class BootstrappedOnlyCompilationTests {
     ).checkCompile()
   }
 
+  @Test def posWithCompilerCC: Unit =
+    implicit val testGroup: TestGroup = TestGroup("compilePosWithCompilerCC")
+    aggregateTests(
+      compileDir("tests/pos-with-compiler-cc/dotc", withCompilerOptions.and("-language:experimental.captureChecking"))
+    ).checkCompile()
+
   @Test def posWithCompiler: Unit = {
     implicit val testGroup: TestGroup = TestGroup("compilePosWithCompiler")
     aggregateTests(

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

@@ -242,7 +242,8 @@ class CompilationTests {
     ).checkCompile()
   }
 
-  @Test def recheck: Unit =
+  //@Test disabled in favor of posWithCompilerCC to save time.
+  def recheck: Unit =
     given TestGroup = TestGroup("recheck")
     aggregateTests(
       compileFilesInDir("tests/new", recheckOptions),

tests/pos-with-compiler-cc/dotc/Bench.scala

@@ -0,0 +1,64 @@
+package dotty.tools
+package dotc
+
+import core.Contexts._
+import reporting.Reporter
+import io.AbstractFile
+
+import scala.annotation.internal.sharable
+
+/** A main class for running compiler benchmarks. Can instantiate a given
+ *  number of compilers and run each (sequentially) a given number of times
+ *  on the same sources.
+ */
+object Bench extends Driver:
+
+  @sharable private var numRuns = 1
+
+  private def ntimes(n: Int)(op: => Reporter): Reporter =
+    (0 until n).foldLeft(emptyReporter)((_, _) => op)
+
+  @sharable private var times: Array[Int] = _
+
+  override def doCompile(compiler: Compiler, files: List[AbstractFile])(using Context): Reporter =
+    times = new Array[Int](numRuns)
+    var reporter: Reporter = emptyReporter
+    for i <- 0 until numRuns do
+      val start = System.nanoTime()
+      reporter = super.doCompile(compiler, files)
+      times(i) = ((System.nanoTime - start) / 1000000).toInt
+      println(s"time elapsed: ${times(i)}ms")
+      if ctx.settings.Xprompt.value then
+        print("hit <return> to continue >")
+        System.in.nn.read()
+        println()
+    reporter
+
+  def extractNumArg(args: Array[String], name: String, default: Int = 1): (Int, Array[String]) = {
+    val pos = args indexOf name
+    if (pos < 0) (default, args)
+    else (args(pos + 1).toInt, (args take pos) ++ (args drop (pos + 2)))
+  }
+
+  def reportTimes() =
+    val best = times.sorted
+    val measured = numRuns / 3
+    val avgBest = best.take(measured).sum / measured
+    val avgLast = times.reverse.take(measured).sum / measured
+    println(s"best out of $numRuns runs: ${best(0)}")
+    println(s"average out of best $measured: $avgBest")
+    println(s"average out of last $measured: $avgLast")
+
+  override def process(args: Array[String], rootCtx: Context): Reporter =
+    val (numCompilers, args1) = extractNumArg(args, "#compilers")
+    val (numRuns, args2) = extractNumArg(args1, "#runs")
+    this.numRuns = numRuns
+    var reporter: Reporter = emptyReporter
+    for i <- 0 until numCompilers do
+      reporter = super.process(args2, rootCtx)
+    reportTimes()
+    reporter
+
+end Bench
+
+

tests/pos-with-compiler-cc/dotc/CompilationUnit.scala

@@ -0,0 +1,166 @@
+package dotty.tools
+package dotc
+
+import core._
+import Contexts._
+import SymDenotations.ClassDenotation
+import Symbols._
+import util.{FreshNameCreator, SourceFile, NoSource}
+import util.Spans.Span
+import ast.{tpd, untpd}
+import tpd.{Tree, TreeTraverser}
+import ast.Trees.{Import, Ident}
+import typer.Nullables
+import transform.SymUtils._
+import core.Decorators._
+import config.{SourceVersion, Feature}
+import StdNames.nme
+import scala.annotation.internal.sharable
+
+class CompilationUnit protected (val source: SourceFile) {
+
+  override def toString: String = source.toString
+
+  var untpdTree: untpd.Tree = untpd.EmptyTree
+
+  var tpdTree: tpd.Tree = tpd.EmptyTree
+
+  /** Is this the compilation unit of a Java file */
+  def isJava: Boolean = source.file.name.endsWith(".java")
+
+  /** The source version for this unit, as determined by a language import */
+  var sourceVersion: Option[SourceVersion] = None
+
+  /** Pickled TASTY binaries, indexed by class. */
+  var pickled: Map[ClassSymbol, () => Array[Byte]] = Map()
+
+  /** The fresh name creator for the current unit.
+   *  FIXME(#7661): This is not fine-grained enough to enable reproducible builds,
+   *  see https://github.com/scala/scala/commit/f50ec3c866263448d803139e119b33afb04ec2bc
+   */
+  val freshNames: FreshNameCreator = new FreshNameCreator.Default
+
+  /** Will be set to `true` if there are inline call that must be inlined after typer.
+   *  The information is used in phase `Inlining` in order to avoid traversing trees that need no transformations.
+   */
+  var needsInlining: Boolean = false
+
+  /** Set to `true` if inliner added anonymous mirrors that need to be completed */
+  var needsMirrorSupport: Boolean = false
+
+  /** Will be set to `true` if contains `Quote`.
+   *  The information is used in phase `Staging`/`Splicing`/`PickleQuotes` in order to avoid traversing trees that need no transformations.
+   */
+  var needsStaging: Boolean = false
+
+  /** Will be set to true if the unit contains a captureChecking language import */
+  var needsCaptureChecking: Boolean = false
+
+  /** Will be set to true if the unit contains a pureFunctions language import */
+  var knowsPureFuns: Boolean = false
+
+  var suspended: Boolean = false
+  var suspendedAtInliningPhase: Boolean = false
+
+  /** Can this compilation unit be suspended */
+  def isSuspendable: Boolean = true
+
+  /** Suspends the compilation unit by thowing a SuspendException
+   *  and recording the suspended compilation unit
+   */
+  def suspend()(using Context): Nothing =
+    assert(isSuspendable)
+    if !suspended then
+      if (ctx.settings.XprintSuspension.value)
+        report.echo(i"suspended: $this")
+      suspended = true
+      ctx.run.nn.suspendedUnits += this
+      if ctx.phase == Phases.inliningPhase then
+        suspendedAtInliningPhase = true
+    throw CompilationUnit.SuspendException()
+
+  private var myAssignmentSpans: Map[Int, List[Span]] | Null = null
+
+  /** A map from (name-) offsets of all local variables in this compilation unit
+   *  that can be tracked for being not null to the list of spans of assignments
+   *  to these variables.
+   */
+  def assignmentSpans(using Context): Map[Int, List[Span]] =
+    if myAssignmentSpans == null then myAssignmentSpans = Nullables.assignmentSpans
+    myAssignmentSpans.nn
+}
+
+@sharable object NoCompilationUnit extends CompilationUnit(NoSource) {
+
+  override def isJava: Boolean = false
+
+  override def suspend()(using Context): Nothing =
+    throw CompilationUnit.SuspendException()
+
+  override def assignmentSpans(using Context): Map[Int, List[Span]] = Map.empty
+}
+
+object CompilationUnit {
+
+  class SuspendException extends Exception
+
+  /** Make a compilation unit for top class `clsd` with the contents of the `unpickled` tree */
+  def apply(clsd: ClassDenotation, unpickled: Tree, forceTrees: Boolean)(using Context): CompilationUnit =
+    val file = clsd.symbol.associatedFile.nn
+    apply(SourceFile(file, Array.empty[Char]), unpickled, forceTrees)
+
+  /** Make a compilation unit, given picked bytes and unpickled tree */
+  def apply(source: SourceFile, unpickled: Tree, forceTrees: Boolean)(using Context): CompilationUnit = {
+    assert(!unpickled.isEmpty, unpickled)
+    val unit1 = new CompilationUnit(source)
+    unit1.tpdTree = unpickled
+    if (forceTrees) {
+      val force = new Force
+      force.traverse(unit1.tpdTree)
+      unit1.needsStaging = force.containsQuote
+      unit1.needsInlining = force.containsInline
+    }
+    unit1
+  }
+
+  /** Create a compilation unit corresponding to `source`.
+   *  If `mustExist` is true, this will fail if `source` does not exist.
+   */
+  def apply(source: SourceFile, mustExist: Boolean = true)(using Context): CompilationUnit = {
+    val src =
+      if (!mustExist)
+        source
+      else if (source.file.isDirectory) {
+        report.error(s"expected file, received directory '${source.file.path}'")
+        NoSource
+      }
+      else if (!source.file.exists) {
+        report.error(s"source file not found: ${source.file.path}")
+        NoSource
+      }
+      else source
+    new CompilationUnit(src)
+  }
+
+  /** Force the tree to be loaded */
+  private class Force extends TreeTraverser {
+    var containsQuote = false
+    var containsInline = false
+    var containsCaptureChecking = false
+    def traverse(tree: Tree)(using Context): Unit = {
+      if (tree.symbol.isQuote)
+        containsQuote = true
+      if tree.symbol.is(Flags.Inline) then
+        containsInline = true
+      tree match
+        case Import(qual, selectors) =>
+          tpd.languageImport(qual) match
+            case Some(prefix) =>
+              for case untpd.ImportSelector(untpd.Ident(imported), untpd.EmptyTree, _) <- selectors do
+                Feature.handleGlobalLanguageImport(prefix, imported)
+            case _ =>
+        case _ =>
+      traverseChildren(tree)
+    }
+  }
+}