fix: hover and go to definition for named tuples (#22202)

resolves: #20500

Author: kasiaMarek

Diff for: presentation-compiler/src/main/dotty/tools/pc/HoverProvider.scala

@@ -104,10 +104,10 @@ object HoverProvider:
       ) match
         case Nil =>
           fallbackToDynamics(path, printer, contentType)
-        case (symbol, tpe) :: _
+        case (symbol, tpe, _) :: _
             if symbol.name == nme.selectDynamic || symbol.name == nme.applyDynamic =>
           fallbackToDynamics(path, printer, contentType)
-        case symbolTpes @ ((symbol, tpe) :: _) =>
+        case symbolTpes @ ((symbol, tpe, None) :: _) =>
           val exprTpw = tpe.widenTermRefExpr.deepDealias
           val hoverString =
             tpw match
@@ -153,6 +153,21 @@ object HoverProvider:
             case _ =>
               ju.Optional.empty().nn
           end match
+        case (_, tpe, Some(namedTupleArg)) :: _ =>
+          val exprTpw = tpe.widenTermRefExpr.deepDealias
+          printer.expressionType(exprTpw) match
+            case Some(tpe) =>
+              ju.Optional.of(
+                new ScalaHover(
+                  expressionType = Some(tpe),
+                  symbolSignature = Some(s"$namedTupleArg: $tpe"),
+                  docstring = None,
+                  forceExpressionType = false,
+                  contextInfo = printer.getUsedRenamesInfo,
+                  contentType = contentType
+                )
+              ).nn
+            case _ => ju.Optional.empty().nn
       end match
     end if
   end hover
@@ -165,23 +180,31 @@ object HoverProvider:
       printer: ShortenedTypePrinter,
       contentType: ContentType
   )(using Context): ju.Optional[HoverSignature] = path match
-    case SelectDynamicExtractor(sel, n, name) =>
+    case SelectDynamicExtractor(sel, n, name, rest) =>
       def findRefinement(tp: Type): Option[HoverSignature] =
         tp match
-          case RefinedType(_, refName, tpe) if name == refName.toString() =>
+          case RefinedType(_, refName, tpe) if (name == refName.toString() || refName.toString() == nme.Fields.toString()) =>
+            val resultType =
+              rest match
+                case Select(_, asInstanceOf) :: TypeApply(_, List(tpe)) :: _ if asInstanceOf == nme.asInstanceOfPM =>
+                    tpe.tpe.widenTermRefExpr.deepDealias
+                case _ if n == nme.selectDynamic => tpe.resultType
+                case _ => tpe
+
             val tpeString =
-              if n == nme.selectDynamic then s": ${printer.tpe(tpe.resultType)}"
-              else printer.tpe(tpe)
+              if n == nme.selectDynamic then s": ${printer.tpe(resultType)}"
+              else printer.tpe(resultType)
 
             val valOrDef =
-              if n == nme.selectDynamic && !tpe.isInstanceOf[ExprType]
-              then "val"
-              else "def"
+              if refName.toString() == nme.Fields.toString() then ""
+              else if n == nme.selectDynamic && !tpe.isInstanceOf[ExprType]
+              then "val "
+              else "def "
 
             Some(
               new ScalaHover(
                 expressionType = Some(tpeString),
-                symbolSignature = Some(s"$valOrDef $name$tpeString"),
+                symbolSignature = Some(s"$valOrDef$name$tpeString"),
                 contextInfo = printer.getUsedRenamesInfo,
                 contentType = contentType
               )
@@ -208,16 +231,16 @@ object SelectDynamicExtractor:
       case Select(_, _) :: Apply(
             Select(Apply(reflSel, List(sel)), n),
             List(Literal(Constant(name: String)))
-          ) :: _
+          ) :: rest
           if (n == nme.selectDynamic || n == nme.applyDynamic) &&
             nme.reflectiveSelectable == reflSel.symbol.name =>
-        Some(sel, n, name)
+        Some(sel, n, name, rest)
       // tests `selectable`,  `selectable2` and `selectable-full` in HoverScala3TypeSuite
       case Select(_, _) :: Apply(
             Select(sel, n),
             List(Literal(Constant(name: String)))
-          ) :: _ if n == nme.selectDynamic || n == nme.applyDynamic =>
-        Some(sel, n, name)
+          ) :: rest if n == nme.selectDynamic || n == nme.applyDynamic =>
+        Some(sel, n, name, rest)
       case _ => None
     end match
   end unapply

Diff for: presentation-compiler/src/main/dotty/tools/pc/MetalsInteractive.scala

@@ -5,12 +5,16 @@ import scala.annotation.tailrec
 
 import dotc.*
 import ast.*, tpd.*
+import dotty.tools.dotc.core.Constants.*
 import core.*, Contexts.*, Flags.*, Names.*, Symbols.*, Types.*
+import dotty.tools.dotc.core.StdNames.*
 import interactive.*
 import util.*
 import util.SourcePosition
+import dotty.tools.pc.utils.InteractiveEnrichments.*
 
 object MetalsInteractive:
+  type NamedTupleArg = String
 
   def contextOfStat(
       stats: List[Tree],
@@ -110,67 +114,67 @@ object MetalsInteractive:
       pos: SourcePosition,
       indexed: IndexedContext,
       skipCheckOnName: Boolean = false
-  ): List[(Symbol, Type)] =
+  ): List[(Symbol, Type, Option[String])] =
     import indexed.ctx
     path match
       // For a named arg, find the target `DefDef` and jump to the param
       case NamedArg(name, _) :: Apply(fn, _) :: _ =>
         val funSym = fn.symbol
         if funSym.is(Synthetic) && funSym.owner.is(CaseClass) then
           val sym = funSym.owner.info.member(name).symbol
-          List((sym, sym.info))
+          List((sym, sym.info, None))
         else
           val paramSymbol =
             for param <- funSym.paramSymss.flatten.find(_.name == name)
             yield param
           val sym = paramSymbol.getOrElse(fn.symbol)
-          List((sym, sym.info))
+          List((sym, sym.info, None))
 
       case (_: untpd.ImportSelector) :: (imp: Import) :: _ =>
         importedSymbols(imp, _.span.contains(pos.span)).map(sym =>
-          (sym, sym.info)
+          (sym, sym.info, None)
         )
 
       case (imp: Import) :: _ =>
         importedSymbols(imp, _.span.contains(pos.span)).map(sym =>
-          (sym, sym.info)
+          (sym, sym.info, None)
         )
 
       // wildcard param
       case head :: _ if (head.symbol.is(Param) && head.symbol.is(Synthetic)) =>
-        List((head.symbol, head.typeOpt))
+        List((head.symbol, head.typeOpt, None))
 
       case (head @ Select(target, name)) :: _
           if head.symbol.is(Synthetic) && name == StdNames.nme.apply =>
         val sym = target.symbol
         if sym.is(Synthetic) && sym.is(Module) then
-          List((sym.companionClass, sym.companionClass.info))
-        else List((target.symbol, target.typeOpt))
+          List((sym.companionClass, sym.companionClass.info, None))
+        else List((target.symbol, target.typeOpt, None))
 
       // L@@ft(...)
       case (head @ ApplySelect(select)) :: _
           if select.qualifier.sourcePos.contains(pos) &&
             select.name == StdNames.nme.apply =>
-        List((head.symbol, head.typeOpt))
+        List((head.symbol, head.typeOpt, None))
 
       // for Inlined we don't have a symbol, but it's needed to show proper type
       case (head @ Inlined(call, bindings, expansion)) :: _ =>
-        List((call.symbol, head.typeOpt))
+        List((call.symbol, head.typeOpt, None))
 
       // for comprehension
       case (head @ ApplySelect(select)) :: _ if isForSynthetic(head) =>
         // If the cursor is on the qualifier, return the symbol for it
         // `for { x <- List(1).head@@Option }`  returns the symbol of `headOption`
         if select.qualifier.sourcePos.contains(pos) then
-          List((select.qualifier.symbol, select.qualifier.typeOpt))
+          List((select.qualifier.symbol, select.qualifier.typeOpt, None))
         // Otherwise, returns the symbol of for synthetics such as "withFilter"
-        else List((head.symbol, head.typeOpt))
+        else List((head.symbol, head.typeOpt, None))
 
       // f@@oo.bar
       case Select(target, _) :: _
           if target.span.isSourceDerived &&
             target.sourcePos.contains(pos) =>
-        List((target.symbol, target.typeOpt))
+        List((target.symbol, target.typeOpt, None))
 
       /* In some cases type might be represented by TypeTree, however it's possible
        * that the type tree will not be marked properly as synthetic even if it doesn't
@@ -185,7 +189,7 @@ object MetalsInteractive:
        */
       case (tpt: TypeTree) :: parent :: _
           if tpt.span != parent.span && !tpt.symbol.is(Synthetic) =>
-        List((tpt.symbol, tpt.typeOpt))
+        List((tpt.symbol, tpt.typeOpt, None))
 
       /* TypeTest class https://dotty.epfl.ch/docs/reference/other-new-features/type-test.html
        * compiler automatically adds unapply if possible, we need to find the type symbol
@@ -195,14 +199,28 @@ object MetalsInteractive:
         pat match
           case UnApply(fun, _, pats) =>
             val tpeSym = pats.head.typeOpt.typeSymbol
-            List((tpeSym, tpeSym.info))
+            List((tpeSym, tpeSym.info, None))
           case _ =>
             Nil
 
+      // Handle select on named tuples
+      case (Apply(Apply(TypeApply(fun, List(t1, t2)), List(ddef)), List(Literal(Constant(i: Int))))) :: _
+        if fun.symbol.exists && fun.symbol.name == nme.apply &&
+            fun.symbol.owner.exists && fun.symbol.owner == getModuleIfDefined("scala.NamedTuple").moduleClass =>
+        def getIndex(t: Tree): Option[Type] =
+          t.tpe.dealias match
+            case AppliedType(_, args) => args.get(i)
+            case _ => None
+        val name = getIndex(t1) match
+          case Some(c: ConstantType) => c.value.stringValue
+          case _ => ""
+        val tpe = getIndex(t2).getOrElse(NoType)
+        List((ddef.symbol, tpe, Some(name)))
+
       case path @ head :: tail =>
         if head.symbol.is(Exported) then
           val sym = head.symbol.sourceSymbol
-          List((sym, sym.info))
+          List((sym, sym.info, None))
         else if head.symbol.is(Synthetic) then
           enclosingSymbolsWithExpressionType(
             tail,
@@ -217,7 +235,7 @@ object MetalsInteractive:
               pos,
               indexed.ctx.source
             )
-          then List((head.symbol, head.typeOpt))
+          then List((head.symbol, head.typeOpt, None))
           /* Type tree for List(1) has an Int type variable, which has span
            * but doesn't exist in code.
            * https://github.com/scala/scala3/issues/15937
@@ -234,7 +252,7 @@ object MetalsInteractive:
               indexed,
               skipCheckOnName
             )
-          else recovered.map(sym => (sym, sym.info))
+          else recovered.map(sym => (sym, sym.info, None))
         end if
       case Nil => Nil
     end match

Diff for: presentation-compiler/src/main/dotty/tools/pc/PcDefinitionProvider.scala

@@ -101,7 +101,7 @@ class PcDefinitionProvider(
     val enclosing = path.expandRangeToEnclosingApply(pos)
     val typeSymbols = MetalsInteractive
       .enclosingSymbolsWithExpressionType(enclosing, pos, indexed)
-      .map { case (_, tpe) =>
+      .map { case (_, tpe, _) =>
         tpe.typeSymbol
       }
     typeSymbols match

Diff for: presentation-compiler/test/dotty/tools/pc/tests/definition/PcDefinitionSuite.scala

@@ -504,3 +504,12 @@ class PcDefinitionSuite extends BasePcDefinitionSuite:
          |val a = MyIntOut(1).un@@even
          |""".stripMargin,
     )
+
+  @Test def `named-tuples` =
+    check(
+      """|import scala.language.experimental.namedTuples
+         |
+         |val <<foo>> = (name = "Bob", age = 42, height = 1.9d)
+         |val foo_name = foo.na@@me
+         |""".stripMargin
+    )

Diff for: presentation-compiler/test/dotty/tools/pc/tests/hover/HoverTermSuite.scala

@@ -717,3 +717,33 @@ class HoverTermSuite extends BaseHoverSuite:
         |""".stripMargin,
       """def ???: Nothing""".stripMargin.hover
   )
+
+  @Test def `named-tuples`: Unit =
+    check(
+      """import scala.language.experimental.namedTuples
+        |
+        |val foo = (name = "Bob", age = 42, height = 1.9d)
+        |val foo_name = foo.na@@me
+        |""".stripMargin,
+      "name: String".hover
+    )
+
+  @Test def `named-tuples2`: Unit =
+    check(
+      """|import scala.language.experimental.namedTuples
+         |
+         |import NamedTuple.*
+         |
+         |class NamedTupleSelectable extends Selectable {
+         |  type Fields <: AnyNamedTuple
+         |  def selectDynamic(name: String): Any = ???
+         |}
+         |
+         |val person = new NamedTupleSelectable {
+         |  type Fields = (name: String, city: String)
+         |}
+         |
+         |val person_name = person.na@@me
+         |""".stripMargin,
+      "name: String".hover
+    )