Merge pull request #8245 from dotty-staging/i8188

Fix #8188: For the purposes of overloading, contextual methods aren't methodic

Author: odersky

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -1824,7 +1824,7 @@ trait Applications extends Compatibility {
       skip(alt.widen)
 
     def resultIsMethod(tp: Type): Boolean = tp.widen.stripPoly match
-      case tp: MethodType => tp.resultType.isInstanceOf[MethodType]
+      case tp: MethodType => stripImplicit(tp.resultType).isInstanceOf[MethodType]
       case _ => false
 
     val found = narrowMostSpecific(candidates)

tests/pos/i2378.scala renamed to tests/neg/i2378.scala

@@ -21,10 +21,10 @@ class Test(val tb: Toolbox) {
   implicit val cap: Cap = null
 
   def foo(tree: Tree): Int = (tree: Any) match {
-    case tb.Apply(fun, args) => 3
+    case tb.Apply(fun, args) => 3  // error: ambiguous overload of unapply
   }
 
   def bar(tree: tpd.Tree): Int = (tree: Any) match {
-    case Apply(fun, args) => 3
+    case Apply(fun, args) => 3  // error: ambiguous overload of unapply
   }
 }

tests/pos/i8188a.scala

@@ -0,0 +1,11 @@
+object Test {
+  extension StrDeco on (tree: String) {
+    def show(using DummyImplicit): String = ???
+    def show(color: Boolean)(using DummyImplicit): String = ???
+  }
+
+  val a: String = "foo".show
+  val b: String = "foo".show(true)
+  val c: Any = "foo".show
+  val d: Any = "foo".show(true)
+}

tests/pos/i8188b.scala

@@ -0,0 +1,6 @@
+class Foo {
+  def f(x: String)(using DummyImplicit): String = x * 2
+  def f(x: String)(color: Boolean)(using DummyImplicit): String = x * 3
+}
+
+@main def Test = println(new Foo().f("foo"))

tests/pos/i8188c.scala

@@ -0,0 +1,6 @@
+class Foo {
+  def f(x: String)(using DummyImplicit): String = x * 2
+  def f(x: String)(using DummyImplicit)(color: Boolean): String = x * 3
+}
+
+@main def Test = println(new Foo().f("foo"))