Support TypeApplication in Synthetic

Author: tanishiking

compiler/src/dotty/tools/dotc/semanticdb/ExtractSemanticDB.scala

@@ -245,6 +245,11 @@ class ExtractSemanticDB extends Phase:
                     registerUseGuarded(None, alt.symbol.companionClass, sel.imported.span, tree.source)
         case tree: Inlined =>
           traverse(tree.call)
+
+        case tree: TypeApply =>
+          synth.tryFindSynthetic(tree).foreach(synthetics.addOne)
+          traverseChildren(tree)
+
         case tree: TypeTree =>
           tree.typeOpt match
             // Any types could be appear inside of `TypeTree`, but

compiler/src/dotty/tools/dotc/semanticdb/SyntheticsExtractor.scala

@@ -11,14 +11,44 @@ import scala.collection.mutable
 class SyntheticsExtractor:
   import Scala3.{_, given}
 
+  val visited = collection.mutable.HashSet[Tree]()
+
   def tryFindSynthetic(tree: Tree)(using Context, SemanticSymbolBuilder, TypeOps): Option[s.Synthetic] =
     extension (synth: s.Synthetic)
       def toOpt: Some[s.Synthetic] = Some(synth)
 
-    if tree.span.isSynthetic then
+    val forSynthetic = tree match // not yet supported (for synthetics)
+      case tree: Apply if isForSynthetic(tree) => true
+      case tree: TypeApply if isForSynthetic(tree) => true
+      case _ => false
+
+    if visited.contains(tree) || forSynthetic then None
+    else
       tree match
-        case tree: Apply if isForSynthetic(tree) =>
-          None // not yet supported (for synthetics)
+        case tree: TypeApply
+          if tree.span.isSynthetic &&
+            tree.args.forall(arg => !arg.symbol.is(Scala2x)) &&
+            !tree.span.isZeroExtent =>
+          visited.add(tree)
+          val fnTree = tree.fun match
+            // Something like `List.apply[Int](1,2,3)`
+            case select @ Select(qual, _) if isSyntheticName(select) =>
+              s.SelectTree(
+                s.OriginalTree(range(qual.span, tree.source)),
+                Some(select.toSemanticId)
+              )
+            case _ =>
+              s.OriginalTree(
+                range(tree.fun.span, tree.source)
+              )
+          val targs = tree.args.map(targ => targ.tpe.toSemanticType(targ.symbol)(using LinkMode.SymlinkChildren))
+          s.Synthetic(
+            range(tree.span, tree.source),
+            s.TypeApplyTree(
+              fnTree, targs
+            )
+          ).toOpt
+
         case tree: Apply
           if tree.args.nonEmpty &&
             tree.args.forall(arg =>
@@ -46,7 +76,6 @@ class SyntheticsExtractor:
           ).toOpt
 
         case _ => None
-    else None
 
   private given TreeOps: AnyRef with
     extension (tree: Tree)
@@ -95,4 +124,15 @@ class SyntheticsExtractor:
       case select: Select => isForComprehensionSyntheticName(select)
       case _ => false
 
+  private def isSyntheticName(select: Select): Boolean =
+    select.span.toSynthetic == select.qualifier.span.toSynthetic && (
+      select.name == nme.apply ||
+      select.name == nme.update ||
+      select.name == nme.foreach ||
+      select.name == nme.withFilter ||
+      select.name == nme.flatMap ||
+      select.name == nme.map ||
+      select.name == nme.unapplySeq ||
+      select.name == nme.unapply)
+
 end SyntheticsExtractor