Also infer a precise type when tracked is not inherited

Author: mbovel

compiler/src/dotty/tools/dotc/typer/Namer.scala

@@ -2016,6 +2016,11 @@ class Namer { typer: Typer =>
       paramFn: Type => Type,
       fallbackProto: Type
     )(using Context): Type =
+    /** Is this member tracked? This is true if it is marked as `tracked` or if
+     *  it overrides a `tracked` member. To account for the later, `isTracked`
+     *  is overriden to `true` as a side-effect of computing `inherited`.
+     */
+    var isTracked: Boolean = sym.is(Tracked)
 
     /** A type for this definition that might be inherited from elsewhere:
      *  If this is a setter parameter, the corresponding getter type.
@@ -2053,15 +2058,12 @@ class Namer { typer: Typer =>
 
           val iDenot = cls.info.nonPrivateDecl(sym.name).matchingDenotation(site, schema, sym.targetName)
           val iSym = iDenot.symbol
+          if iSym.is(Tracked) then isTracked = true
           val iRawInfo = iDenot.info
           val iResType = instantiatedResType(iRawInfo, paramss).asSeenFrom(site, cls)
-          if iSym.is(Tracked) && !mdef.rhs.isEmpty then
-            // When inherting a tracked member, we infer a precise type from the rhs
-            tp & typedAheadExpr(mdef.rhs, iResType).tpe
-          else
-            if (iResType.exists)
-              typr.println(i"using inherited type for ${mdef.name}; raw: $iRawInfo, inherited: $iResType")
-            tp & iResType
+          if (iResType.exists)
+            typr.println(i"using inherited type for ${mdef.name}; raw: $iRawInfo, inherited: $iResType")
+          tp & iResType
         }
     end inherited
 
@@ -2146,6 +2148,7 @@ class Namer { typer: Typer =>
             if defaultTp.exists then TypeOps.SimplifyKeepUnchecked() else null)
         match
           case ctp: ConstantType if sym.isInlineVal => ctp
+          case tp if isTracked => tp
           case tp => TypeComparer.widenInferred(tp, pt, Widen.Unions)
 
     // Replace aliases to Unit by Unit itself. If we leave the alias in
@@ -2156,7 +2159,7 @@ class Namer { typer: Typer =>
     def lhsType = fullyDefinedType(cookedRhsType, "right-hand side", mdef.srcPos)
     //if (sym.name.toString == "y") println(i"rhs = $rhsType, cooked = $cookedRhsType")
     if (inherited.exists)
-      if sym.isInlineVal then lhsType else inherited
+      if sym.isInlineVal || isTracked then lhsType else inherited
     else {
       if (sym.is(Implicit))
         mdef match {