From 164a8edc59d4e62bb4de99e15d1e986c16e2a503 Mon Sep 17 00:00:00 2001
From: Jan Chyb <jan.chyb.99@gmail.com>
Date: Tue, 26 Nov 2024 17:21:14 +0100
Subject: [PATCH] Add a check for correct Array shape in
 quotes.reflect.ClassOfConstant

---
 .../scala/quoted/runtime/impl/QuotesImpl.scala    | 12 +++++++++++-
 tests/neg-macros/i21916.check                     | 15 +++++++++++++++
 tests/neg-macros/i21916/Macro_1.scala             |  9 +++++++++
 tests/neg-macros/i21916/Test_2.scala              |  1 +
 4 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 tests/neg-macros/i21916.check
 create mode 100644 tests/neg-macros/i21916/Macro_1.scala
 create mode 100644 tests/neg-macros/i21916/Test_2.scala

diff --git a/compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala b/compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala
index 22be293c3562..2559334fa996 100644
--- a/compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala
+++ b/compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala
@@ -2519,7 +2519,17 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
 
     object ClassOfConstant extends ClassOfConstantModule:
       def apply(x: TypeRepr): ClassOfConstant =
-        // TODO check that the type is a valid class when creating this constant or let Ycheck do it?
+        // We only check if the supplied TypeRepr is valid if it contains an Array,
+        // as so far only that Array could cause issues
+        def correctTypeApplicationForArray(typeRepr: TypeRepr): Boolean =
+            val isArray = typeRepr.typeSymbol != dotc.core.Symbols.defn.ArrayClass
+            typeRepr match
+              case AppliedType(_, Nil) => isArray
+              case _ => isArray
+        xCheckMacroAssert(
+          correctTypeApplicationForArray(x),
+          "Illegal empty Array type constructor. Please supply a type parameter."
+        )
         dotc.core.Constants.Constant(x)
       def unapply(constant: ClassOfConstant): Some[TypeRepr] = Some(constant.typeValue)
     end ClassOfConstant
diff --git a/tests/neg-macros/i21916.check b/tests/neg-macros/i21916.check
new file mode 100644
index 000000000000..b07bc5736bd9
--- /dev/null
+++ b/tests/neg-macros/i21916.check
@@ -0,0 +1,15 @@
+
+-- Error: tests/neg-macros/i21916/Test_2.scala:1:33 --------------------------------------------------------------------
+1 |@main def Test: Unit = Macro.test() // error
+  |                       ^^^^^^^^^^^^
+  |                   Exception occurred while executing macro expansion.
+  |                   java.lang.AssertionError: Illegal empty Array type constructor. Please supply a type parameter.
+  |                   	at Macro$.testImpl(Macro_1.scala:8)
+  |
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |This location contains code that was inlined from Macro_1.scala:3
+3 |  inline def test() = ${testImpl}
+  |                      ^^^^^^^^^^^
+   ---------------------------------------------------------------------------------------------------------------------
diff --git a/tests/neg-macros/i21916/Macro_1.scala b/tests/neg-macros/i21916/Macro_1.scala
new file mode 100644
index 000000000000..78af2cde2963
--- /dev/null
+++ b/tests/neg-macros/i21916/Macro_1.scala
@@ -0,0 +1,9 @@
+import scala.quoted._
+object Macro:
+  inline def test() = ${testImpl}
+  def testImpl(using Quotes): Expr[Any] = {
+    import quotes.reflect._
+    val tpe = TypeRepr.of[Array[Byte]] match
+      case AppliedType(tycons, _) => tycons
+    Literal(ClassOfConstant(tpe)).asExpr
+  }
diff --git a/tests/neg-macros/i21916/Test_2.scala b/tests/neg-macros/i21916/Test_2.scala
new file mode 100644
index 000000000000..da8bf436a33c
--- /dev/null
+++ b/tests/neg-macros/i21916/Test_2.scala
@@ -0,0 +1 @@
+@main def Test: Unit = Macro.test() // error