From 8cbec9218f80e8ab7cc7a7103659617a3edfd05d Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Tue, 12 May 2020 15:05:56 +0200
Subject: [PATCH] Fix #7839: Improve error message for implicit parameters

---
 compiler/src/dotty/tools/dotc/transform/Splicer.scala | 6 +++---
 tests/neg-macros/i7839.check                          | 8 ++++++++
 tests/neg-macros/i7839.scala                          | 6 ++++++
 3 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 tests/neg-macros/i7839.check
 create mode 100644 tests/neg-macros/i7839.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/Splicer.scala b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
index 2e535d58d0e3..38c38ac42eff 100644
--- a/compiler/src/dotty/tools/dotc/transform/Splicer.scala
+++ b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
@@ -160,12 +160,12 @@ object Splicer {
           // OK
 
         case _ =>
+          val extra = if tree.span.isZeroExtent then ": " + tree.show else ""
           ctx.error(
-            """Malformed macro parameter
+            s"""Malformed macro parameter$extra
               |
-              |Parameters may be:
+              |Parameters may only be:
               | * Quoted parameters or fields
-              | * References to inline parameters
               | * Literal values of primitive types
               |""".stripMargin, tree.sourcePos)
       }
diff --git a/tests/neg-macros/i7839.check b/tests/neg-macros/i7839.check
new file mode 100644
index 000000000000..197867ab809b
--- /dev/null
+++ b/tests/neg-macros/i7839.check
@@ -0,0 +1,8 @@
+-- Error: tests/neg-macros/i7839.scala:4:18 ----------------------------------------------------------------------------
+4 |  ${ transformImpl } // error
+  |                  ^
+  |                  Malformed macro parameter: dummyImplicit
+  |
+  |                  Parameters may only be:
+  |                   * Quoted parameters or fields
+  |                   * Literal values of primitive types
diff --git a/tests/neg-macros/i7839.scala b/tests/neg-macros/i7839.scala
new file mode 100644
index 000000000000..60536771b2bd
--- /dev/null
+++ b/tests/neg-macros/i7839.scala
@@ -0,0 +1,6 @@
+import scala.quoted._
+
+inline def transform(using dummyImplicit: DummyImplicit): Unit =
+  ${ transformImpl } // error
+
+def transformImpl(using dummyImplicit: DummyImplicit)(using QuoteContext): Expr[Unit] = ???