Enable fatal warnings everywhere.

build.sbt

@@ -2,6 +2,16 @@ import org.scalajs.linker.interface.OutputPatterns
 
 val scalaV = "2.13.12"
 
+inThisBuild(Def.settings(
+  scalacOptions ++= Seq(
+    "-encoding",
+    "utf-8",
+    "-feature",
+    "-deprecation",
+    "-Xfatal-warnings",
+  )
+))
+
 lazy val cli = project
   .in(file("cli"))
   .enablePlugins(ScalaJSPlugin)

wasm/src/main/scala/ir2wasm/WasmBuilder.scala

@@ -32,9 +32,9 @@ class WasmBuilder {
     }
   }
 
-  def transformTopLevelExport(export: LinkedTopLevelExport)(implicit ctx: WasmContext): Unit = {
+  def transformTopLevelExport(topLevelExport: LinkedTopLevelExport)(implicit ctx: WasmContext): Unit = {
     implicit val fctx = WasmFunctionContext()
-    export.tree match {
+    topLevelExport.tree match {
       case d: IRTrees.TopLevelFieldExportDef   => ???
       case d: IRTrees.TopLevelJSClassExportDef => ???
       case d: IRTrees.TopLevelMethodExportDef  => transformToplevelMethodExportDef(d)
@@ -370,11 +370,11 @@ class WasmBuilder {
     )
     ctx.addFunction(func)
 
-    val export = new WasmExport.Function(
+    val exprt = new WasmExport.Function(
       methodName.value,
       func
     )
-    ctx.addExport(export)
+    ctx.addExport(exprt)
   }
 
   private def genFunction(

wasm/src/main/scala/wasm4s/Wasm.scala

@@ -133,7 +133,7 @@ class WasmModule(
   def addFunctionType(typ: WasmFunctionType): Unit = _functionTypes.addOne(typ)
   def addRecGroupType(typ: WasmStructType): Unit = _recGroupTypes.addOne(typ)
   def addGlobal(typ: WasmGlobal): Unit = _globals.addOne(typ)
-  def addExport(export: WasmExport[_]) = _exports.addOne(export)
+  def addExport(exprt: WasmExport[_]) = _exports.addOne(exprt)
 
   def functionTypes = _functionTypes.toList
   def recGroupTypes = WasmModule.tsort(_recGroupTypes.toList)
@@ -157,8 +157,8 @@ object WasmModule {
       } else {
         val found = noPreds.map { _._1 }.toSet
         val updated = hasPreds.map {
-          case (k, Some(v)) => // should be safe because hasPreds has no None
-            (k, if (found.contains(v)) None else Some(v))
+          case (k, v) =>
+            (k, v.filter(!found.contains(_)))
         }
         tsort(updated, done ++ found)
       }

wasm/src/main/scala/wasm4s/WasmContext.scala

@@ -96,7 +96,7 @@ trait FunctionTypeWriterWasmContext extends ReadOnlyWasmContext { this: WasmCont
 
 class WasmContext(val module: WasmModule) extends FunctionTypeWriterWasmContext {
   import WasmContext._
-  def addExport(export: WasmExport[_]): Unit = module.addExport(export)
+  def addExport(exprt: WasmExport[_]): Unit = module.addExport(exprt)
   def addFunction(fun: WasmFunction): Unit = {
     module.addFunction(fun)
     functions.define(fun)