From 30cf42ee3a23d74aa17d2ab06a3dc200c7f0fc8a Mon Sep 17 00:00:00 2001
From: Gleb Koval <gleb@koval.net>
Date: Wed, 5 Feb 2025 05:12:32 +0000
Subject: [PATCH] fix: separate variable and function in scope

---
 src/main/wacc/Error.scala   |  2 +-
 src/main/wacc/renamer.scala | 48 +++++++++++++++++++++++--------------
 src/main/wacc/types.scala   |  2 --
 3 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/src/main/wacc/Error.scala b/src/main/wacc/Error.scala
index a9f0490..6370925 100644
--- a/src/main/wacc/Error.scala
+++ b/src/main/wacc/Error.scala
@@ -2,7 +2,7 @@ package wacc
 
 enum Error {
   case DuplicateDeclaration(ident: ast.Ident)
-  case UndefinedIdentifier(ident: ast.Ident)
+  case UndefinedIdentifier(ident: ast.Ident, identType: renamer.IdentType)
   case FunctionParamsMismatch(expected: Int, got: Int)
   case TypeMismatch(expected: types.SemType, got: types.SemType)
 }
diff --git a/src/main/wacc/renamer.scala b/src/main/wacc/renamer.scala
index 023b317..cdfe19d 100644
--- a/src/main/wacc/renamer.scala
+++ b/src/main/wacc/renamer.scala
@@ -6,24 +6,29 @@ object renamer {
   import ast._
   import types._
 
+  enum IdentType {
+    case Func
+    case Var
+  }
+
   private case class Scope(
-      current: mutable.Map[String, Ident],
-      parent: Map[String, Ident]
+      current: mutable.Map[(String, IdentType), Ident],
+      parent: Map[(String, IdentType), Ident]
   ) {
     def subscope: Scope =
       Scope(mutable.Map.empty, Map.empty.withDefault(current.withDefault(parent)))
 
-    def add(semType: SemType, name: Ident)(using
+    def add(semType: SemType, name: Ident, identType: IdentType)(using
         globalNames: mutable.Map[Ident, SemType],
         globalNumbering: mutable.Map[String, Int],
         errors: mutable.Builder[Error, List[Error]]
     ) = {
-      if (current.contains(name.v)) {
+      if (current.contains((name.v, identType))) {
         errors += Error.DuplicateDeclaration(name)
       } else {
         val uid = globalNumbering.getOrElse(name.v, 0)
         name.uid = uid
-        current(name.v) = name
+        current((name.v, identType)) = name
 
         globalNames(name) = semType
         globalNumbering(name.v) = uid + 1
@@ -54,16 +59,16 @@ object renamer {
       val functionScope = scope.subscope
       val paramTypes = params.map { param =>
         val paramType = SemType(param.paramType)
-        functionScope.add(paramType, param.name)
+        functionScope.add(paramType, param.name, IdentType.Var)
         paramType
       }
-      scope.add(KnownType.Func(SemType(retType), paramTypes), name)
+      scope.add(KnownType.Func(SemType(retType), paramTypes), name, IdentType.Func)
       body.toList.foreach(rename(functionScope))
     }
     case VarDecl(synType, name, value) => {
       // Order matters here. Variable isn't declared until after the value is evaluated.
       rename(scope)(value)
-      scope.add(SemType(synType), name)
+      scope.add(SemType(synType), name, IdentType.Var)
     }
     case Assign(lhs, value) => {
       rename(scope)(lhs)
@@ -89,7 +94,7 @@ object renamer {
       rename(scope)(snd)
     }
     case Call(name, args) => {
-      rename(scope)(name)
+      renameIdent(scope, name, IdentType.Func)
       args.foreach(rename(scope))
     }
     case Fst(elem)         => rename(scope)(elem)
@@ -105,15 +110,22 @@ object renamer {
       rename(scope)(op.x)
       rename(scope)(op.y)
     }
-    case id: Ident => {
-      scope.current.withDefault(scope.parent).get(id.v) match {
-        case Some(Ident(_, uid)) => id.uid = uid
-        case None => {
-          errors += Error.UndefinedIdentifier(id)
-          scope.add(?, id)
-        }
-      }
-    }
+    // Default to variables. Only `call` uses IdentType.Func.
+    case id: Ident => renameIdent(scope, id, IdentType.Var)
     case IntLiter(_) | BoolLiter(_) | CharLiter(_) | StrLiter(_) | PairLiter | Skip => ()
   }
+
+  private def renameIdent(scope: Scope, ident: Ident, identType: IdentType)(using
+      globalNames: mutable.Map[Ident, SemType],
+      globalNumbering: mutable.Map[String, Int],
+      errors: mutable.Builder[Error, List[Error]]
+  ): Unit = {
+    scope.current.withDefault(scope.parent).get((ident.v, identType)) match {
+      case Some(Ident(_, uid)) => ident.uid = uid
+      case None => {
+        errors += Error.UndefinedIdentifier(ident, identType)
+        scope.add(?, ident, identType)
+      }
+    }
+  }
 }
diff --git a/src/main/wacc/types.scala b/src/main/wacc/types.scala
index 2ce5f27..388416f 100644
--- a/src/main/wacc/types.scala
+++ b/src/main/wacc/types.scala
@@ -1,7 +1,5 @@
 package wacc
 
-import scala.collection.mutable
-
 object types {
   import ast._