From a8871fb1bee9f7b11669ee737daa3ef05157e6aa Mon Sep 17 00:00:00 2001
From: Harry Li <me@flandia.dev>
Date: Fri, 7 Feb 2025 15:42:24 +0800
Subject: [PATCH] Validate number of arguments in application

---
 .../hkmc2/semantics/ImplicitResolver.scala    | 16 +++++++---------
 .../src/test/mlscript/backlog/ToTriage.mls    | 19 +++++++++++--------
 .../src/test/mlscript/basics/StrTest.mls      | 17 ++++++++++++-----
 3 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/semantics/ImplicitResolver.scala b/hkmc2/shared/src/main/scala/hkmc2/semantics/ImplicitResolver.scala
index d5653c53a0..d4f83e2e6e 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/semantics/ImplicitResolver.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/semantics/ImplicitResolver.scala
@@ -139,15 +139,13 @@ class ImplicitResolver(tl: TraceLogger)
         val paramss = tdf.params
         (paramss zip argss).foreach: 
           case (ps, Term.Tup(args)) =>
-            // * TODO: Check the arity.
-            // if ps.paramCountUB
-            // then if ps.paramCountLB != args.length then
-            //   raise(ErrorReport(msg"Expected ${ps.paramCountLB.toString()} arguments, " +
-            //     msg"got ${args.length.toString()}" -> base.toLoc :: Nil))
-            // else if ps.paramCountLB > args.length then
-            //   raise(ErrorReport(msg"Expected at least ${ps.paramCountLB.toString()} arguments, " +
-            //     msg"got ${args.length.toString()}" -> base.toLoc :: Nil))
-            assert(ps.params.sizeCompare(args) === 0)
+            if ps.paramCountUB
+            then if ps.paramCountLB != args.length then
+              raise(ErrorReport(msg"Expected ${ps.paramCountLB.toString()} arguments, " +
+                msg"got ${args.length.toString()}" -> base.toLoc :: Nil))
+            else if ps.paramCountLB > args.length then
+              raise(ErrorReport(msg"Expected at least ${ps.paramCountLB.toString()} arguments, " +
+                msg"got ${args.length.toString()}" -> base.toLoc :: Nil))
             (ps.params zip args).foreach((p, arg) => resolveArg(p, arg)(base))
           case _ =>
             lastWords("Other argument forms.")
diff --git a/hkmc2/shared/src/test/mlscript/backlog/ToTriage.mls b/hkmc2/shared/src/test/mlscript/backlog/ToTriage.mls
index 3ac7fe664b..63ae3dce7b 100644
--- a/hkmc2/shared/src/test/mlscript/backlog/ToTriage.mls
+++ b/hkmc2/shared/src/test/mlscript/backlog/ToTriage.mls
@@ -89,6 +89,9 @@ set g.0 = g.0 + 1
 :todo // TODO instrument Predef
 :re
 id(1, 2)
+//│ ╔══[ERROR] Expected 1 arguments, got 2
+//│ ║  l.91: 	id(1, 2)
+//│ ╙──      	^^
 //│ = 1
 
 // ——— ——— ———
@@ -149,7 +152,7 @@ f of
       2
   of 3
 //│ ╔══[PARSE ERROR] Expected end of input; found indented block instead
-//│ ║  l.150: 	  of 3
+//│ ║  l.153: 	  of 3
 //│ ╙──       	^^
 //│ = [function]
 
@@ -180,7 +183,7 @@ object Oops with
 :e
 Oops.fakeField
 //│ ╔══[ERROR] Object 'Oops' does not contain member 'fakeField'
-//│ ║  l.181: 	Oops.fakeField
+//│ ║  l.184: 	Oops.fakeField
 //│ ╙──       	    ^^^^^^^^^^
 //│ = 1
 
@@ -246,7 +249,7 @@ object Cls(x) with
 :e
 Cls.x
 //│ ╔══[ERROR] Object 'Cls' does not contain member 'x'
-//│ ║  l.247: 	Cls.x
+//│ ║  l.250: 	Cls.x
 //│ ╙──       	   ^^
 //│ ═══[RUNTIME ERROR] Error: Access to required field 'x' yielded 'undefined'
 
@@ -274,15 +277,15 @@ module Example with
 // whoops
   val a = this
 //│ ╔══[PARSE ERROR] Expected block after type declaration body; found newline instead
-//│ ║  l.273: 	module Example with
+//│ ║  l.276: 	module Example with
 //│ ║         	                   ^
-//│ ║  l.274: 	// whoops
+//│ ║  l.277: 	// whoops
 //│ ╙──       	
 //│ ╔══[PARSE ERROR] Expected an expression; found block instead
-//│ ║  l.275: 	  val a = this
+//│ ║  l.278: 	  val a = this
 //│ ╙──       	  ^
 //│ ╔══[PARSE ERROR] Expected end of input; found indented block instead
-//│ ║  l.275: 	  val a = this
+//│ ║  l.278: 	  val a = this
 //│ ╙──       	^^
 
 // ——— ——— ———
@@ -290,7 +293,7 @@ module Example with
 :fixme // ("Not in scope" error)
 let xs = new Oopsie
 //│ ╔══[ERROR] Name not found: Oopsie
-//│ ║  l.291: 	let xs = new Oopsie
+//│ ║  l.294: 	let xs = new Oopsie
 //│ ╙──       	             ^^^^^^
 //│ /!!!\ Uncaught error: hkmc2.InternalError: Not in scope: xs (class hkmc2.semantics.VarSymbol)
 
diff --git a/hkmc2/shared/src/test/mlscript/basics/StrTest.mls b/hkmc2/shared/src/test/mlscript/basics/StrTest.mls
index 5dd5ff6249..19d1a96663 100644
--- a/hkmc2/shared/src/test/mlscript/basics/StrTest.mls
+++ b/hkmc2/shared/src/test/mlscript/basics/StrTest.mls
@@ -17,24 +17,31 @@ concat of
 
 // TODO (~) should be sanitized
 
+:e
 (~)("a", "b", "c")
+//│ ╔══[ERROR] Expected 2 arguments, got 3
+//│ ║  l.21: 	(~)("a", "b", "c")
+//│ ╙──      	 ^
 //│ = "ab"
 
-
+:e
 (~)("a")
+//│ ╔══[ERROR] Expected 2 arguments, got 1
+//│ ║  l.28: 	(~)("a")
+//│ ╙──      	 ^
 //│ = "aundefined"
 
 :ge
 ~"a"
 //│ ╔══[COMPILATION ERROR] Unexpected type annotations ~"a"
-//│ ║  l.28: 	~"a"
+//│ ║  l.35: 	~"a"
 //│ ╙──      	 ^^^
 
 
 :ge
 ~("a", "b")
 //│ ╔══[COMPILATION ERROR] Unexpected type annotations ~{ "a"; "b" }
-//│ ║  l.35: 	~("a", "b")
+//│ ║  l.42: 	~("a", "b")
 //│ ╙──      	       ^^^
 
 
@@ -42,10 +49,10 @@ concat of
 :ge
 ~ of "a", "b"
 //│ ╔══[PARSE ERROR] Expected start of statement in this position; found 'of' keyword instead
-//│ ║  l.43: 	~ of "a", "b"
+//│ ║  l.50: 	~ of "a", "b"
 //│ ╙──      	  ^^
 //│ ╔══[PARSE ERROR] Expected end of input; found literal instead
-//│ ║  l.43: 	~ of "a", "b"
+//│ ║  l.50: 	~ of "a", "b"
 //│ ╙──      	     ^^^
 //│ ═══[COMPILATION ERROR] Unexpected type annotations ~<error>