From 880350d830b62de21ab68f779c2932814add9897 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Tue, 31 Aug 2021 14:49:53 +0200
Subject: [PATCH] Do not bind inline parameters when lifting args

Fixes #13411
---
 .../dotty/tools/dotc/typer/EtaExpansion.scala |  6 ++--
 tests/pos/i13411.scala                        | 12 +++++++
 tests/pos/i13411b/Constants.java              |  5 +++
 tests/pos/i13411b/Test.scala                  | 32 +++++++++++++++++++
 4 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 tests/pos/i13411.scala
 create mode 100644 tests/pos/i13411b/Constants.java
 create mode 100644 tests/pos/i13411b/Test.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/EtaExpansion.scala b/compiler/src/dotty/tools/dotc/typer/EtaExpansion.scala
index 32849de6f560..74891fccd985 100644
--- a/compiler/src/dotty/tools/dotc/typer/EtaExpansion.scala
+++ b/compiler/src/dotty/tools/dotc/typer/EtaExpansion.scala
@@ -88,8 +88,10 @@ abstract class Lifter {
     methRef.widen match {
       case mt: MethodType =>
         args.lazyZip(mt.paramNames).lazyZip(mt.paramInfos).map { (arg, name, tp) =>
-          val lifter = if (tp.isInstanceOf[ExprType]) exprLifter else this
-          lifter.liftArg(defs, arg, if (name.firstPart contains '$') EmptyTermName else name)
+          if tp.hasAnnotation(defn.InlineParamAnnot) then arg
+          else
+            val lifter = if (tp.isInstanceOf[ExprType]) exprLifter else this
+            lifter.liftArg(defs, arg, if (name.firstPart contains '$') EmptyTermName else name)
         }
       case _ =>
         args.mapConserve(liftArg(defs, _))
diff --git a/tests/pos/i13411.scala b/tests/pos/i13411.scala
new file mode 100644
index 000000000000..d310cdbdad21
--- /dev/null
+++ b/tests/pos/i13411.scala
@@ -0,0 +1,12 @@
+class Foo
+class Bar extends Foo
+
+inline def thingy(a: Int = 0, b: Int = 0, inline c: Foo = new Bar) = {
+  inline c match {
+    case _: Bar =>
+  }
+}
+
+def x = 1
+
+def test = thingy(b = x)
diff --git a/tests/pos/i13411b/Constants.java b/tests/pos/i13411b/Constants.java
new file mode 100644
index 000000000000..0cb5fb31ac5e
--- /dev/null
+++ b/tests/pos/i13411b/Constants.java
@@ -0,0 +1,5 @@
+public class Constants {
+  public static final int A = 0;
+  public static final int B = 2;
+  public static final int C = 3;
+}
diff --git a/tests/pos/i13411b/Test.scala b/tests/pos/i13411b/Test.scala
new file mode 100644
index 000000000000..4ed586485d86
--- /dev/null
+++ b/tests/pos/i13411b/Test.scala
@@ -0,0 +1,32 @@
+class broken {
+  sealed trait Foo
+  case object A extends Foo
+  case object B extends Foo
+  case object C extends Foo
+  case object D extends Foo
+
+  inline def foo(inline f: Foo) = inline f match {
+    case _: A.type => "the letter a"
+    case _: B.type => "the letter b"
+    case _: C.type => "the letter c"
+    case _: D.type => "the letter d"
+  }
+
+  inline def thingy(
+    depthClampEnable: Boolean = false,
+    rasterizerDiscardEnable: Boolean = false,
+    polygonMode: Int = 0,
+    cullMode: Int = 0,
+    frontFace: Int = 0,
+    depthBiasEnable: Boolean = false,
+    depthBiasConstantFactor: Float = 0,
+    depthBiasClamp: Float = 0,
+    depthBiasSlopeFactor: Float = 0,
+    lineWidth: Float = 0,
+    inline f: Foo = A,
+  ) = {
+    foo(f)
+  }
+
+  thingy(polygonMode = Constants.A, cullMode = Constants.B, frontFace = Constants.C, lineWidth = 1.0f)
+}