Decouple -print-tasty from compiler

To print the contents of a tasty file we only need the bytes of the file.
The current architecture forced us to load the context and have a wroking classpath.
When debugging, we sometimes need to see the contents of a tasty file witouth having the full classpath available.

* Use `dotty.tools.dotc.core.TastyPrinter.main` as new entry point
* Decouple `-decompile` from `-print-tasty`
* Only require .tasty file to be able to print its contents
* Keep the same CLI commands and flags

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala

@@ -11,14 +11,42 @@ import TastyUnpickler._
 import util.Spans.offsetToInt
 import printing.Highlighting._
 import dotty.tools.tasty.TastyFormat.{ASTsSection, PositionsSection, CommentsSection}
+import java.nio.file.{Files, Paths}
 
 object TastyPrinter:
-  def show(bytes: Array[Byte])(using Context): String =
+
+  def showContents(bytes: Array[Byte], noColor: Boolean): String =
     val printer =
-      if ctx.settings.color.value == "never" then new TastyPrinter(bytes)
+      if noColor then new TastyPrinter(bytes)
       else new TastyAnsiiPrinter(bytes)
     printer.showContents()
 
+  def main(args: Array[String]): Unit = {
+    // TODO: Decouple CliCommand from Context and use CliCommand.distill?
+    val lineWidth = 80
+    val line = "-" * lineWidth
+    val noColor = args.contains("-color:never")
+    var printLastLine = false
+    for arg <- args if arg != "-print-tasty" do
+      if arg == "-print-tasty" || arg == "-color:never" then () // skip
+      else if arg.startsWith("-") then println(s"bad option '$arg' was ignored")
+      else if !arg.endsWith(".tasty") then println(s"Not a '.tasty' file: $arg")
+      else {
+        val path = Paths.get(arg)
+        if !Files.exists(path) then println("File not found: " + arg)
+        else
+          val bytes = Files.readAllBytes(path)
+          println(line)
+          println(arg)
+          println(line)
+          println(showContents(bytes, noColor))
+          println()
+          printLastLine = true
+      }
+    if printLastLine then
+      println(line)
+  }
+
 class TastyPrinter(bytes: Array[Byte]) {
 
   private val sb: StringBuilder = new StringBuilder

compiler/src/dotty/tools/dotc/decompiler/DecompilationPrinter.scala

@@ -40,12 +40,8 @@ class DecompilationPrinter extends Phase {
 
   private def printToOutput(out: PrintStream)(using Context): Unit = {
     val unit = ctx.compilationUnit
-    if (ctx.settings.printTasty.value)
-      println(TastyPrinter.show(unit.pickled.head._2()))
-    else {
-      val unitFile = unit.source.toString.replace("\\", "/").replace(".class", ".tasty")
-      out.println(s"/** Decompiled from $unitFile */")
-      out.println(QuotesImpl.showDecompiledTree(unit.tpdTree))
-    }
+    val unitFile = unit.source.toString.replace("\\", "/").replace(".class", ".tasty")
+    out.println(s"/** Decompiled from $unitFile */")
+    out.println(QuotesImpl.showDecompiledTree(unit.tpdTree))
   }
 }

compiler/src/dotty/tools/dotc/quoted/PickledQuotes.scala

@@ -174,7 +174,7 @@ object PickledQuotes {
       positionWarnings.foreach(report.warning(_))
 
     val pickled = pickler.assembleParts()
-    quotePickling.println(s"**** pickled quote\n${TastyPrinter.show(pickled)}")
+    quotePickling.println(s"**** pickled quote\n${TastyPrinter.showContents(pickled, ctx.settings.color.value == "never")}")
     pickled
   }
 
@@ -195,7 +195,7 @@ object PickledQuotes {
           case pickled: String => TastyString.unpickle(pickled)
           case pickled: List[String] => TastyString.unpickle(pickled)
 
-        quotePickling.println(s"**** unpickling quote from TASTY\n${TastyPrinter.show(bytes)}")
+        quotePickling.println(s"**** unpickling quote from TASTY\n${TastyPrinter.showContents(bytes, ctx.settings.color.value == "never")}")
 
         val mode = if (isType) UnpickleMode.TypeTree else UnpickleMode.Term
         val unpickler = new DottyUnpickler(bytes, mode)

compiler/src/dotty/tools/dotc/transform/Pickler.scala

@@ -91,7 +91,7 @@ class Pickler extends Phase {
           if pickling ne noPrinter then
             pickling.synchronized {
               println(i"**** pickled info of $cls")
-              println(TastyPrinter.show(pickled))
+              println(TastyPrinter.showContents(pickled, ctx.settings.color.value == "never"))
             }
           pickled
         }(using ExecutionContext.global)

compiler/test/dotty/tools/dotc/core/tasty/PathPicklingTest.scala

@@ -34,36 +34,29 @@ class PathPicklingTest {
     locally {
       val ignorantProcessLogger = ProcessLogger(_ => ())
       val options = TestConfiguration.defaultOptions
-        .and("-d", s"$out/out.jar")
+        .and("-d", out.toString)
         .and("-sourceroot", "tests/pos")
         .and(s"$cwd/tests/pos/i10430/lib.scala", s"$cwd/tests/pos/i10430/app.scala")
       val reporter = TestReporter.reporter(System.out, logLevel = ERROR)
       val rep = Main.process(options.all, reporter)
       assertFalse("Compilation failed.", rep.hasErrors)
     }
 
-    val decompiled =
-      val outstream = new ByteArrayOutputStream()
-      val options = TestConfiguration.defaultOptions
-        .and("-print-tasty")
-        .and("-color:never")
-        .and(s"$out/out.jar")
-      val reporter = TestReporter.reporter(System.out, logLevel = ERROR)
-      val rep = Console.withOut(outstream) {
-        decompiler.Main.process(options.all, reporter)
-      }
-      assertFalse("Decompilation failed.", rep.hasErrors)
-      new String(outstream.toByteArray(), "UTF-8")
+    def showTasty(path: String) =
+      val bytes = Files.readAllBytes(Paths.get(path))
+      TastyPrinter.showContents(bytes, noColor = true)
 
-    assertTrue(decompiled.contains(": i10430/lib.scala"))
-    assertTrue(decompiled.contains(": i10430/app.scala"))
-    assertTrue(decompiled.contains("[i10430/lib.scala]"))
-    assertTrue(decompiled.contains("[i10430/app.scala]"))
+    val libTasty = showTasty(s"$out/lib.tasty")
+    assertTrue(libTasty.contains(": i10430/lib.scala"))
+    assertTrue(libTasty.contains("[i10430/lib.scala]"))
+    assertFalse(libTasty.contains(": i10430\\lib.scala"))
+    assertFalse(libTasty.contains("[i10430\\lib.scala]"))
 
-    assertFalse(decompiled.contains(": i10430\\lib.scala"))
-    assertFalse(decompiled.contains(": i10430\\app.scala"))
-    assertFalse(decompiled.contains("[i10430\\lib.scala]"))
-    assertFalse(decompiled.contains("[i10430\\app.scala]"))
+    val appTasty = showTasty(s"$out/app.tasty")
+    assertTrue(appTasty.contains(": i10430/app.scala"))
+    assertTrue(appTasty.contains("[i10430/app.scala]"))
+    assertFalse(appTasty.contains(": i10430\\app.scala"))
+    assertFalse(appTasty.contains("[i10430\\app.scala]"))
   }
 
   private def delete(file: JFile): Unit = {

dist/bin/common

@@ -200,6 +200,7 @@ default_java_opts="-Xmx768m -Xms768m"
 
 CompilerMain=dotty.tools.dotc.Main
 DecompilerMain=dotty.tools.dotc.decompiler.Main
+TastyPrinterMain=dotty.tools.dotc.core.tasty.TastyPrinter
 ReplMain=dotty.tools.repl.Main
 ScriptingMain=dotty.tools.scripting.Main
 

dist/bin/scalac

@@ -45,7 +45,7 @@ case "$1" in
                while [[ $# -gt 0 ]]; do addScript "$1" && shift ; done ;;
      -compile) PROG_NAME="$CompilerMain" && shift ;;
    -decompile) PROG_NAME="$DecompilerMain" && shift ;;
- -print-tasty) PROG_NAME="$DecompilerMain" && addScala "-print-tasty" && shift ;;
+ -print-tasty) PROG_NAME="$TastyPrinterMain" && shift ;;
          -run) PROG_NAME="$ReplMain" && shift ;;
       -colors) colors=true && shift ;;
    -no-colors) unset colors && shift ;;

project/Build.scala

@@ -643,13 +643,14 @@ object Build {
             arg != "-with-compiler" && arg != "-Ythrough-tasty")
 
         val main =
-          if (decompile || printTasty) "dotty.tools.dotc.decompiler.Main"
+          if (decompile) "dotty.tools.dotc.decompiler.Main"
+          else if (printTasty) "dotty.tools.dotc.core.tasty.TastyPrinter"
           else if (debugFromTasty) "dotty.tools.dotc.fromtasty.Debug"
           else "dotty.tools.dotc.Main"
 
         var extraClasspath = Seq(scalaLib, dottyLib)
 
-        if ((decompile || printTasty) && !args.contains("-classpath"))
+        if (decompile && !args.contains("-classpath"))
           extraClasspath ++= Seq(".")
 
         if (args0.contains("-with-compiler")) {
@@ -664,7 +665,7 @@ object Build {
           extraClasspath ++= Seq(dottyCompiler, dottyInterfaces, asm, dottyStaging, dottyTastyInspector, tastyCore)
         }
 
-        val fullArgs = main :: insertClasspathInArgs(args, extraClasspath.mkString(File.pathSeparator))
+        val fullArgs = main :: (if (printTasty) args else insertClasspathInArgs(args, extraClasspath.mkString(File.pathSeparator)))
 
         (Compile / runMain).toTask(fullArgs.mkString(" ", " ", ""))
       }.evaluated,

project/scripts/cmdTests

@@ -23,10 +23,16 @@ clear_out "$OUT"
 "$SBT" ";scalac $SOURCE ; scala $MAIN" > "$tmp"
 grep -qe "$EXPECTED_OUTPUT" "$tmp"
 
+echo "testing sbt scalac -print-tasty"
+clear_out "$OUT"
+"$SBT" ";scalac $SOURCE -d $OUT ;scalac -print-tasty -color:never $TASTY" > "$tmp"
+grep -qe "0: ASTs" "$tmp"
+grep -qe "0: tests/pos/HelloWorld.scala" "$tmp"
+
 echo "testing that paths SourceFile annotations are relativized"
 clear_out "$OUT"
-"$SBT" "scalac -d $OUT/out.jar -sourceroot tests/pos $(pwd)/tests/pos/i10430/lib.scala $(pwd)/tests/pos/i10430/app.scala"
-"$SBT" "scalac -decompile -print-tasty -color:never $OUT/out.jar" > "$tmp"
+"$SBT" "scalac -d $OUT -sourceroot tests/pos $(pwd)/tests/pos/i10430/lib.scala $(pwd)/tests/pos/i10430/app.scala"
+"$SBT" "scalac -print-tasty -color:never $OUT/lib.tasty $OUT/app.tasty" > "$tmp"
 cat "$tmp" # for debugging
 grep -q ": i10430/lib.scala" "$tmp"
 grep -q ": i10430/app.scala" "$tmp"
@@ -82,3 +88,5 @@ clear_out "$OUT"
 #     fi
 #   fi
 # done 3<"$tmp1" 4<"./tests/vulpix-tests/meta/sbt-output.check"
+
+echo "cmdTests successful"