Backport "Add Stable Presentation Compiler" to LTS (#19061)

Backports #17528 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: Kordyjan

NOTICE.md

@@ -89,15 +89,19 @@ major authors were omitted by oversight.
     details.
 
   * dotty.tools.dotc.coverage: Coverage instrumentation utilities have been
-    adapted from the scoverage plugin for scala 2 [5], which is under the
+    adapted from the scoverage plugin for scala 2 [4], which is under the
     Apache 2.0 license.
 
+  * dooty.tools.pc: Presentation compiler implementation adapted from
+    scalameta/metals [5] mtags module, which is under the Apache 2.0 license.
+
   * The Dotty codebase contains parts which are derived from
-    the ScalaPB protobuf library [4], which is under the Apache 2.0 license.
+    the ScalaPB protobuf library [6], which is under the Apache 2.0 license.
 
 
 [1] https://github.com/scala/scala
 [2] https://github.com/adriaanm/scala/tree/sbt-api-consolidate/src/compiler/scala/tools/sbt
 [3] https://github.com/sbt/sbt/tree/0.13/compile/interface/src/main/scala/xsbt
-[4] https://github.com/lampepfl/dotty/pull/5783/files
-[5] https://github.com/scoverage/scalac-scoverage-plugin
+[4] https://github.com/scoverage/scalac-scoverage-plugin
+[5] https://github.com/scalameta/metals
+[6] https://github.com/lampepfl/dotty/pull/5783/files

build.sbt

@@ -28,6 +28,8 @@ val `scala3-bench-run` = Build.`scala3-bench-run`
 val dist = Build.dist
 val `community-build` = Build.`community-build`
 val `sbt-community-build` = Build.`sbt-community-build`
+val `scala3-presentation-compiler` = Build.`scala3-presentation-compiler`
+val `scala3-presentation-compiler-bootstrapped` = Build.`scala3-presentation-compiler-bootstrapped`
 
 val sjsSandbox = Build.sjsSandbox
 val sjsJUnitTests = Build.sjsJUnitTests

compiler/src/dotty/tools/dotc/CompilationUnit.scala

@@ -5,6 +5,7 @@ import core._
 import Contexts._
 import SymDenotations.ClassDenotation
 import Symbols._
+import Comments.Comment
 import util.{FreshNameCreator, SourceFile, NoSource}
 import util.Spans.Span
 import ast.{tpd, untpd}
@@ -69,6 +70,9 @@ class CompilationUnit protected (val source: SourceFile) {
   /** Can this compilation unit be suspended */
   def isSuspendable: Boolean = true
 
+  /** List of all comments present in this compilation unit */
+  var comments: List[Comment] = Nil
+
   /** Suspends the compilation unit by thowing a SuspendException
    *  and recording the suspended compilation unit
    */

compiler/src/dotty/tools/dotc/interactive/InteractiveDriver.scala

@@ -145,7 +145,7 @@ class InteractiveDriver(val settings: List[String]) extends Driver {
     (fromSource ++ fromClassPath).distinct
   }
 
-  def run(uri: URI, sourceCode: String): List[Diagnostic] = run(uri, toSource(uri, sourceCode))
+  def run(uri: URI, sourceCode: String): List[Diagnostic] = run(uri, SourceFile.virtual(uri, sourceCode))
 
   def run(uri: URI, source: SourceFile): List[Diagnostic] = {
     import typer.ImportInfo._
@@ -297,9 +297,6 @@ class InteractiveDriver(val settings: List[String]) extends Driver {
     cleanupTree(tree)
   }
 
-  private def toSource(uri: URI, sourceCode: String): SourceFile =
-    SourceFile.virtual(Paths.get(uri).toString, sourceCode)
-
   /**
    * Initialize this driver and compiler.
    *
@@ -323,7 +320,7 @@ object InteractiveDriver {
     else
       try
         // We don't use file.file here since it'll be null
-        // for the VirtualFiles created by InteractiveDriver#toSource
+        // for the VirtualFiles created by SourceFile#virtual
         // TODO: To avoid these round trip conversions, we could add an
         // AbstractFile#toUri method and implement it by returning a constant
         // passed as a parameter to a constructor of VirtualFile

compiler/src/dotty/tools/dotc/parsing/ParserPhase.scala

@@ -30,6 +30,7 @@ class Parser extends Phase {
         val p = new Parsers.Parser(unit.source)
         //  p.in.debugTokenStream = true
         val tree = p.parse()
+        ctx.compilationUnit.comments = p.in.comments
         if (p.firstXmlPos.exists && !firstXmlPos.exists)
           firstXmlPos = p.firstXmlPos
         tree

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -227,11 +227,11 @@ object Scanners {
       */
     private var docstringMap: SortedMap[Int, Comment] = SortedMap.empty
 
-    /* A Buffer for comment positions */
-    private val commentPosBuf = new mutable.ListBuffer[Span]
+    /* A Buffer for comments */
+    private val commentBuf = new mutable.ListBuffer[Comment]
 
-    /** Return a list of all the comment positions */
-    def commentSpans: List[Span] = commentPosBuf.toList
+    /** Return a list of all the comments */
+    def comments: List[Comment] = commentBuf.toList
 
     private def addComment(comment: Comment): Unit = {
       val lookahead = lookaheadReader()
@@ -246,7 +246,7 @@ object Scanners {
     def getDocComment(pos: Int): Option[Comment] = docstringMap.get(pos)
 
     /** A buffer for comments */
-    private val commentBuf = CharBuffer(initialCharBufferSize)
+    private val currentCommentBuf = CharBuffer(initialCharBufferSize)
 
     def toToken(identifier: SimpleName): Token =
       def handleMigration(keyword: Token): Token =
@@ -523,7 +523,7 @@ object Scanners {
      *
      *      The following tokens can start an indentation region:
      *
-     *         :  =  =>  <-  if  then  else  while  do  try  catch  
+     *         :  =  =>  <-  if  then  else  while  do  try  catch
      *         finally  for  yield  match  throw  return  with
      *
      *      Inserting an INDENT starts a new indentation region with the indentation of the current
@@ -1019,7 +1019,7 @@ object Scanners {
 
     private def skipComment(): Boolean = {
       def appendToComment(ch: Char) =
-        if (keepComments) commentBuf.append(ch)
+        if (keepComments) currentCommentBuf.append(ch)
       def nextChar() = {
         appendToComment(ch)
         Scanner.this.nextChar()
@@ -1047,9 +1047,9 @@ object Scanners {
       def finishComment(): Boolean = {
         if (keepComments) {
           val pos = Span(start, charOffset - 1, start)
-          val comment = Comment(pos, commentBuf.toString)
-          commentBuf.clear()
-          commentPosBuf += pos
+          val comment = Comment(pos, currentCommentBuf.toString)
+          currentCommentBuf.clear()
+          commentBuf += comment
 
           if (comment.isDocComment)
             addComment(comment)
@@ -1065,7 +1065,7 @@ object Scanners {
       else if (ch == '*') { nextChar(); skipComment(); finishComment() }
       else {
         // This was not a comment, remove the `/` from the buffer
-        commentBuf.clear()
+        currentCommentBuf.clear()
         false
       }
     }

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -179,7 +179,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
         if (printWithoutPrefix.contains(tp.symbol))
           toText(tp.name)
         else
-          toTextPrefix(tp.prefix) ~ selectionString(tp)
+          toTextPrefixOf(tp) ~ selectionString(tp)
       case tp: TermParamRef =>
         ParamRefNameString(tp) ~ lambdaHash(tp.binder) ~ ".type"
       case tp: TypeParamRef =>
@@ -353,7 +353,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
   def toTextRef(tp: SingletonType): Text = controlled {
     tp match {
       case tp: TermRef =>
-        toTextPrefix(tp.prefix) ~ selectionString(tp)
+        toTextPrefixOf(tp) ~ selectionString(tp)
       case tp: ThisType =>
         nameString(tp.cls) + ".this"
       case SuperType(thistpe: SingletonType, _) =>
@@ -375,15 +375,6 @@ class PlainPrinter(_ctx: Context) extends Printer {
     }
   }
 
-  /** The string representation of this type used as a prefix, including separator */
-  def toTextPrefix(tp: Type): Text = controlled {
-    homogenize(tp) match {
-      case NoPrefix => ""
-      case tp: SingletonType => toTextRef(tp) ~ "."
-      case tp => trimPrefix(toTextLocal(tp)) ~ "#"
-    }
-  }
-
   def toTextCaptureRef(tp: Type): Text =
     homogenize(tp) match
       case tp: TermRef if tp.symbol == defn.captureRoot => Str("cap")
@@ -393,6 +384,15 @@ class PlainPrinter(_ctx: Context) extends Printer {
   protected def isOmittablePrefix(sym: Symbol): Boolean =
     defn.unqualifiedOwnerTypes.exists(_.symbol == sym) || isEmptyPrefix(sym)
 
+  /** The string representation of type prefix, including separator */
+  def toTextPrefixOf(tp: NamedType): Text = controlled {
+      homogenize(tp.prefix) match {
+        case NoPrefix => ""
+        case tp: SingletonType => toTextRef(tp) ~ "."
+        case tp => trimPrefix(toTextLocal(tp)) ~ "#"
+      }
+  }
+
   protected def isEmptyPrefix(sym: Symbol): Boolean =
     sym.isEffectiveRoot || sym.isAnonymousClass || sym.name.isReplWrapperName
 

compiler/src/dotty/tools/dotc/printing/Printer.scala

@@ -4,7 +4,7 @@ package printing
 
 import core._
 import Texts._, ast.Trees._
-import Types.{Type, SingletonType, LambdaParam},
+import Types.{Type, SingletonType, LambdaParam, NamedType},
        Symbols.Symbol, Scopes.Scope, Constants.Constant,
        Names.Name, Denotations._, Annotations.Annotation, Contexts.Context
 import typer.Implicits.*
@@ -101,7 +101,7 @@ abstract class Printer {
   def toTextRef(tp: SingletonType): Text
 
   /** Textual representation of a prefix of some reference, ending in `.` or `#` */
-  def toTextPrefix(tp: Type): Text
+  def toTextPrefixOf(tp: NamedType): Text
 
   /** Textual representation of a reference in a capture set */
   def toTextCaptureRef(tp: Type): Text

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -117,21 +117,22 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     }
   }
 
-  override def toTextPrefix(tp: Type): Text = controlled {
+  override def toTextPrefixOf(tp: NamedType): Text = controlled {
     def isOmittable(sym: Symbol) =
       if printDebug then false
       else if homogenizedView then isEmptyPrefix(sym) // drop <root> and anonymous classes, but not scala, Predef.
       else if sym.isPackageObject then isOmittablePrefix(sym.owner)
       else isOmittablePrefix(sym)
-    tp match {
-      case tp: ThisType if isOmittable(tp.cls) =>
+
+    tp.prefix match {
+      case thisType: ThisType if isOmittable(thisType.cls) =>
         ""
-      case tp @ TermRef(pre, _) =>
-        val sym = tp.symbol
-        if sym.isPackageObject && !homogenizedView && !printDebug then toTextPrefix(pre)
+      case termRef @ TermRef(pre, _) =>
+        val sym = termRef.symbol
+        if sym.isPackageObject && !homogenizedView && !printDebug then toTextPrefixOf(termRef)
         else if (isOmittable(sym)) ""
-        else super.toTextPrefix(tp)
-      case _ => super.toTextPrefix(tp)
+        else super.toTextPrefixOf(tp)
+      case _ => super.toTextPrefixOf(tp)
     }
   }
 
@@ -427,8 +428,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       case id @ Ident(name) =>
         val txt = tree.typeOpt match {
           case tp: NamedType if name != nme.WILDCARD =>
-            val pre = if (tp.symbol.is(JavaStatic)) tp.prefix.widen else tp.prefix
-            toTextPrefix(pre) ~ withPos(selectionString(tp), tree.sourcePos)
+            toTextPrefixOf(tp) ~ withPos(selectionString(tp), tree.sourcePos)
           case _ =>
             toText(name)
         }

compiler/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala

@@ -83,8 +83,8 @@ object SyntaxHighlighting {
         }
       }
 
-      for (span <- scanner.commentSpans)
-        highlightPosition(span, CommentColor)
+      for (comment <- scanner.comments)
+        highlightPosition(comment.span, CommentColor)
 
       object TreeHighlighter extends untpd.UntypedTreeTraverser {
         import untpd._