Fix inline function types as macros args

* Show that there is no semantic difference between
  inline functions and by name functions

Author: nicolasstucki

compiler/src/dotty/tools/dotc/transform/Splicer.scala

@@ -65,7 +65,7 @@ object Splicer {
         val args1 = args.head.zip(tp.paramInfos).map {
           case (arg: Literal, tp) if tp.hasAnnotation(defn.InlineParamAnnot) => arg.const.value
           case (arg, tp) =>
-            assert(!tp.hasAnnotation(defn.InlineParamAnnot))
+            assert(!tp.hasAnnotation(defn.InlineParamAnnot) || defn.isFunctionType(tp))
             // Replace argument by its binding
             val arg1 = bindMap.getOrElse(arg, arg)
             new scala.quoted.Exprs.TastyTreeExpr(arg1)

tests/run/quote-inline-function.check

@@ -0,0 +1,47 @@
+Normal function
+{
+  var i: Int = 0
+  val j: Int = 5
+  <label> def while$(): Unit = 
+    if i.<(j) then 
+      {
+        val x$1: Int = i
+        f.apply(x$1)
+        i = i.+(1)
+        while$()
+      }
+     else ()
+  while$()
+}
+
+By name function
+{
+  var i: Int = 0
+  val j: Int = 5
+  <label> def while$(): Unit = 
+    if i.<(j) then 
+      {
+        val x$1: Int = i
+        scala.Predef.println(x$1)
+        i = i.+(1)
+        while$()
+      }
+     else ()
+  while$()
+}
+
+inline function
+{
+  var i: Int = 0
+  val j: Int = 5
+  <label> def while$(): Unit = 
+    if i.<(j) then 
+      {
+        val x$1: Int = i
+        scala.Predef.println(x$1)
+        i = i.+(1)
+        while$()
+      }
+     else ()
+  while$()
+}

tests/run/quote-inline-function/quoted_1.scala

@@ -0,0 +1,22 @@
+import scala.quoted._
+
+import dotty.tools.dotc.quoted.Toolbox._
+
+object Macros {
+
+  inline def foreach1(start: Int, end: Int, f: Int => Unit): String = ~impl('(start), '(end), '(f))
+  inline def foreach2(start: Int, end: Int, f: => Int => Unit): String = ~impl('(start), '(end), '(f))
+  inline def foreach3(start: Int, end: Int, inline f: Int => Unit): String = ~impl('(start), '(end), '(f))
+
+  def impl(start: Expr[Int], end: Expr[Int], f: Expr[Int => Unit]): Expr[String] = {
+    val res = '{
+      var i = ~start
+      val j = ~end
+      while (i < j) {
+        ~f.apply('(i))
+        i += 1
+      }
+    }
+    res.show.toExpr
+  }
+}

tests/run/quote-inline-function/quoted_2.scala

@@ -0,0 +1,18 @@
+import scala.quoted._
+import Macros._
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    println("Normal function")
+    println(foreach1(0, 5, x => println(x)))
+    println()
+
+    println("By name function")
+    println(foreach2(0, 5, x => println(x)))
+    println()
+
+    println("inline function")
+    println(foreach3(0, 5, x => println(x)))
+
+  }
+}