Partial revert of previous commit.

Instead of avoiding fully qualified names,
use a different separator in zincMangledName.

Author: bishabosha

compiler/src/dotty/tools/dotc/core/NameTags.scala

@@ -40,6 +40,8 @@ object NameTags extends TastyFormat.NameTags {
   inline val EXPLICITFIELD = 38  // An explicitly named field, introduce to avoid a clash
                                  // with a regular field of the underlying name
 
+  inline val ZINCMANGLED = 39  // a reserved tag for use in Zinc name mangling (replace `.` by `::`)
+
   def nameTagToString(tag: Int): String = tag match {
     case UTF8 => "UTF8"
     case QUALIFIED => "QUALIFIED"
@@ -61,6 +63,7 @@ object NameTags extends TastyFormat.NameTags {
     case PARAMACC => "PARAMACC"
     case ADAPTEDCLOSURE => "ADAPTEDCLOSURE"
     case OBJECTCLASS => "OBJECTCLASS"
+    case ZINCMANGLED => "ZINCMANGLED"
 
     case SIGNED => "SIGNED"
     case TARGETSIGNED => "TARGETSIGNED"

compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala

@@ -79,6 +79,9 @@ class ExtractAPI extends Phase {
       val pw = new PrintWriter(File(sourceFile.file.jpath).changeExtension("inc").toFile
         .bufferedWriter(append = true), true)
       try {
+        pw.println()
+        pw.println("API:")
+        pw.println("====")
         classes.foreach(source => pw.println(DefaultShowAPI(source)))
       } finally pw.close()
     }

compiler/src/dotty/tools/dotc/sbt/package.scala

@@ -4,17 +4,23 @@ import dotty.tools.dotc.core.Contexts.Context
 import dotty.tools.dotc.core.Symbols.Symbol
 import dotty.tools.dotc.core.NameOps.stripModuleClassSuffix
 import dotty.tools.dotc.core.Names.Name
+import dotty.tools.dotc.core.NameKinds.QualifiedNameKind
+import dotty.tools.dotc.core.NameTags.ZINCMANGLED
 
 inline val TermNameHash = 1987 // 300th prime
 inline val TypeNameHash = 1993 // 301st prime
 inline val InlineParamHash = 1997 // 302nd prime
 
-extension (sym: Symbol)
+private inline val ZINC_MANGLED_SEPARATOR   = "::"
+
+/** Expanded names of the form `prefix :: name`. These only occur in zinc phases, and should not be written to TASTy */
+private[sbt] val ZincMangledName: QualifiedNameKind = new QualifiedNameKind(ZINCMANGLED, ZINC_MANGLED_SEPARATOR)
 
-  def constructorName(using Context) =
-    sym.owner.name ++ ";init;"
+extension (sym: Symbol)
 
-  /** Mangle a JVM symbol name in a format better suited for internal uses by sbt. */
-  def zincMangledName(using Context): Name =
-    if (sym.isConstructor) constructorName
+  /** Mangle a JVM symbol name in a format better suited for internal uses by sbt.
+   *  WARNING: output must not be written to TASTy, as it is not a valid TASTy name.
+   */
+  private[sbt] def zincMangledName(using Context): Name =
+    if (sym.isConstructor) sym.owner.fullNameSeparated(ZincMangledName) ++ ";init;"
     else sym.name.stripModuleClassSuffix

sbt-bridge/test/xsbt/ExtractUsedNamesSpecification.scala

@@ -306,7 +306,7 @@ class ExtractUsedNamesSpecification {
     // All classes extend Object
     "Object",
     // All classes have a default constructor called <init>
-    "Object;init;",
+    "java::lang::Object;init;",
     // the return type of the default constructor is Unit
     "Unit"
   )