Enforce module parameters to receive only module arguments

Author: FlandiaYingman

hkmc2/shared/src/main/scala/hkmc2/semantics/Elaborator.scala

@@ -232,7 +232,36 @@ extends Importer:
       term(rhs)
     case tree @ App(lhs, rhs) =>
       val sym = FlowSymbol("‹app-res›", nextUid)
-      Term.App(term(lhs), term(rhs))(tree, sym)
+      val lt = term(lhs)
+      val rt = term(rhs)
+
+      // Check if module arguments match module parameters
+      val args = rt match
+        case Term.Tup(fields) => S(fields)
+        case _ => N
+      val params = lt.symbol
+        .filter(_.isInstanceOf[BlockMemberSymbol])
+        .flatMap(_.asInstanceOf[BlockMemberSymbol].trmTree)
+        .filter(_.isInstanceOf[TermDef])
+        .flatMap(_.asInstanceOf[TermDef].paramLists.headOption)
+      for
+        (args, params) <- (args zip params)
+        (arg, param) <- (args zip params.fields)
+      do 
+        val argMod = arg.flags.mod
+        val paramMod = param match
+          case Tree.TypeDef(Mod, _, _, _) => true
+          case _ => false
+        if argMod && !paramMod then
+          raise:
+            ErrorReport:
+              msg"Module values can only be passed to module parameters." -> arg.toLoc :: Nil
+        if !argMod && paramMod then
+          raise:
+            ErrorReport:
+              msg"Module parameters can only receive module values." -> arg.toLoc :: Nil
+      
+      Term.App(lt, rt)(tree, sym)
     case Sel(pre, nme) =>
       val preTrm = term(pre)
       val sym = resolveField(nme, preTrm.symbol, nme)

hkmc2/shared/src/test/mlscript/basics/ModuleMethods.mls

@@ -124,6 +124,9 @@ f1(new C)
 // Error: module values can only be passed to module parameters.
 :e
 f1(M) 
+//│ ╔══[ERROR] Module values can only be passed to module parameters.
+//│ ║  l.126: 	f1(M) 
+//│ ╙──       	   ^
 //│ Elaborated tree:
 //│ Blk:
 //│   stats = Nil
@@ -133,12 +136,11 @@ f1(M)
 //│       nme = Ident of "f1"
 //│     rhs = Tup of Ls of 
 //│       Fld:
-//│         flags = ()
+//│         flags = (module)
 //│         value = Sel:
 //│           prefix = Ref of globalThis:block#1
 //│           nme = Ident of "M"
 //│         asc = N
-//│ FAILURE: Unexpected lack of type error
 
 
 // Good: m is a module parameter, therefore the module method foo can be called on m.
@@ -206,7 +208,7 @@ f2(M)
 //│       nme = Ident of "f2"
 //│     rhs = Tup of Ls of 
 //│       Fld:
-//│         flags = ()
+//│         flags = (module)
 //│         value = Sel:
 //│           prefix = Ref of globalThis:block#1
 //│           nme = Ident of "M"
@@ -276,6 +278,9 @@ fun id[T](t: T): T = t
 // Error: Module values can only be passed to module parameters.
 :e
 id(IntMT)
+//│ ╔══[ERROR] Module values can only be passed to module parameters.
+//│ ║  l.280: 	id(IntMT)
+//│ ╙──       	   ^^^^^
 //│ Elaborated tree:
 //│ Blk:
 //│   stats = Nil
@@ -285,12 +290,11 @@ id(IntMT)
 //│       nme = Ident of "id"
 //│     rhs = Tup of Ls of 
 //│       Fld:
-//│         flags = ()
+//│         flags = (module)
 //│         value = Sel:
 //│           prefix = Ref of globalThis:block#9
 //│           nme = Ident of "IntMT"
 //│         asc = N
-//│ FAILURE: Unexpected lack of type error
 
 
 // Good: module parameters must have an explicit and concrete type. 
@@ -330,7 +334,7 @@ idMod(IntMT)
 //│       nme = Ident of "idMod"
 //│     rhs = Tup of Ls of 
 //│       Fld:
-//│         flags = ()
+//│         flags = (module)
 //│         value = Sel:
 //│           prefix = Ref of globalThis:block#9
 //│           nme = Ident of "IntMT"