From a725e4031da2ee3e381a9c90579bbc54475b2c8b Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Wed, 15 Dec 2021 15:46:29 +0100
Subject: [PATCH] Check for splices in quoted macro parameters

Closes #12225
---
 compiler/src/dotty/tools/dotc/transform/Splicer.scala | 9 ++++++++-
 tests/neg-macros/i12225.scala                         | 7 +++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 tests/neg-macros/i12225.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/Splicer.scala b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
index 06162ef513fa..49b6f5564620 100644
--- a/compiler/src/dotty/tools/dotc/transform/Splicer.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
@@ -149,7 +149,14 @@ object Splicer {
         case Typed(expr, _) => checkIfValidArgument(expr)
 
         case Apply(Select(Apply(fn, quoted :: Nil), nme.apply), _) if fn.symbol == defn.QuotedRuntime_exprQuote =>
-          // OK
+          val noSpliceChecker = new TreeTraverser {
+            def traverse(tree: Tree)(using Context): Unit = tree match
+              case Spliced(_) =>
+                report.error("Quoted argument of macros may not have splices", tree.srcPos)
+              case _ =>
+                traverseChildren(tree)
+          }
+          noSpliceChecker.traverse(quoted)
 
         case Apply(TypeApply(fn, List(quoted)), _)if fn.symbol == defn.QuotedTypeModule_of =>
           // OK
diff --git a/tests/neg-macros/i12225.scala b/tests/neg-macros/i12225.scala
new file mode 100644
index 000000000000..66d619aad634
--- /dev/null
+++ b/tests/neg-macros/i12225.scala
@@ -0,0 +1,7 @@
+object TestMacro {
+  inline def test[T](inline t: T): T = ${ identity('{ identity(${ identity('{ identity(${ identity('t) }) }) }) }) } // error
+}
+
+object Test {
+  TestMacro.test("x")
+}