Upgrade Scala 3.5.2 → 3.8.2 and sbt 1.10.6 → 1.11.6

Fix 26 new warnings from stricter Scala 3.8 compiler:
- Remove unused imports and pattern variables
- Add @unused annotations for intentionally kept params
- Suppress false positive on SimParams case class defaults
- Remove BankId.== extension (E194 shadowing)

Author: speedcom

build.sbt

@@ -1,4 +1,4 @@
-val scala3Version = "3.5.2"
+val scala3Version = "3.8.2"
 
 lazy val root = project
   .in(file("."))

project/build.properties

@@ -1 +1 @@
-sbt.version=1.10.6
+sbt.version=1.11.6

src/main/scala/sfc/agents/Banking.scala

@@ -1,7 +1,6 @@
 package sfc.agents
 
 import sfc.config.SimParams
-import sfc.engine.*
 import sfc.engine.mechanisms.{Macroprudential, YieldCurve}
 import sfc.types.*
 import sfc.util.KahanSum.*

src/main/scala/sfc/agents/Household.scala

@@ -690,14 +690,14 @@ object Household:
   /** Base income, benefit, and updated status for one HH. */
   private def computeIncome(hh: State)(using SimParams): (PLN, PLN, HhStatus) =
     hh.status match
-      case HhStatus.Employed(firmId, sectorIdx, wage)    =>
+      case HhStatus.Employed(firmId, sectorIdx, wage) =>
         (wage, PLN.Zero, hh.status)
-      case HhStatus.Unemployed(months)                   =>
+      case HhStatus.Unemployed(months)                =>
         val benefit = computeBenefit(months)
         (benefit, benefit, HhStatus.Unemployed(months + 1))
-      case HhStatus.Retraining(monthsLeft, target, cost) =>
+      case HhStatus.Retraining(monthsLeft, _, cost)   =>
         (PLN.Zero, PLN.Zero, hh.status)
-      case HhStatus.Bankrupt                             =>
+      case HhStatus.Bankrupt                          =>
         (PLN.Zero, PLN.Zero, HhStatus.Bankrupt)
 
   /** Skill decay for long-term unemployed (onset after scarringOnset months).

src/main/scala/sfc/agents/Immigration.scala

@@ -23,7 +23,7 @@ object Immigration:
   /** Monthly immigration inflow. Exogenous: fixed rate × workingAgePop.
     * Endogenous: responds to (domesticWage / foreignWage − 1) × elasticity.
     */
-  def computeInflow(workingAgePop: Int, wage: PLN, unempRate: Double, month: Int)(using p: SimParams): Int =
+  def computeInflow(workingAgePop: Int, wage: PLN, unempRate: Double, @scala.annotation.unused month: Int)(using p: SimParams): Int =
     if !p.flags.immigration then 0
     else if p.flags.immigEndogenous then
       val wageGap = (wage.toDouble / p.immigration.foreignWage.toDouble - 1.0).max(0.0)

src/main/scala/sfc/agents/Nbfi.scala

@@ -121,16 +121,16 @@ object Nbfi:
     */
   def step(
       prev: State,
-      employed: Int,       // employed workers
-      wage: PLN,           // average monthly wage
-      priceLevel: Double,  // CPI price level (unused in current spec, kept for interface stability)
-      unempRate: Ratio,    // unemployment rate
-      bankNplRatio: Ratio, // aggregate bank NPL ratio (tightness signal)
-      govBondYield: Rate,  // government bond yield (annualised)
-      corpBondYield: Rate, // corporate bond yield (annualised)
-      equityReturn: Rate,  // equity monthly return
-      depositRate: Rate,   // bank deposit rate (TFI opportunity cost)
-      domesticCons: PLN,   // domestic consumption (NBFI credit base)
+      employed: Int,                               // employed workers
+      wage: PLN,                                   // average monthly wage
+      @scala.annotation.unused priceLevel: Double, // CPI price level (unused in current spec, kept for interface stability)
+      unempRate: Ratio,                            // unemployment rate
+      bankNplRatio: Ratio,                         // aggregate bank NPL ratio (tightness signal)
+      govBondYield: Rate,                          // government bond yield (annualised)
+      corpBondYield: Rate,                         // corporate bond yield (annualised)
+      equityReturn: Rate,                          // equity monthly return
+      depositRate: Rate,                           // bank deposit rate (TFI opportunity cost)
+      domesticCons: PLN,                           // domestic consumption (NBFI credit base)
   )(using p: SimParams): State =
     // TFI: inflow + investment income + rebalance
     val netInflow = tfiInflow(employed, wage, equityReturn, govBondYield, depositRate)

src/main/scala/sfc/config/SimParams.scala

@@ -47,6 +47,7 @@ case class SectorDef(
   * Polish GDP (~3.5 bln PLN). Do NOT construct SimParams directly with unscaled
   * values — always start from `defaults` and use `.copy()`.
   */
+@annotation.nowarn("msg=unused private member") // Scala 3.8 false positive: defaults used via copy()
 case class SimParams private (
     flags: FeatureFlags = FeatureFlags(),
     pop: PopulationConfig = PopulationConfig(),

src/main/scala/sfc/engine/Simulation.scala

@@ -3,7 +3,6 @@ package sfc.engine
 import sfc.accounting.*
 import sfc.agents.*
 import sfc.config.*
-import sfc.types.*
 
 import scala.util.Random
 

src/main/scala/sfc/engine/markets/IntermediateMarket.scala

@@ -1,6 +1,6 @@
 package sfc.engine.markets
 
-import sfc.agents.{Firm, TechState}
+import sfc.agents.Firm
 import sfc.config.SimParams
 import sfc.types.*
 import sfc.util.KahanSum.*

src/main/scala/sfc/engine/markets/LaborMarket.scala

@@ -83,7 +83,7 @@ object LaborMarket:
       households: Vector[Household.State],
       firms: Vector[Firm.State],
       marketWage: PLN,
-      rng: Random,
+      @scala.annotation.unused rng: Random,
   )(using p: SimParams): JobSearchResult =
     val vacancies = computeVacancies(households, firms)
     if vacancies.isEmpty then JobSearchResult(households, 0)