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

Author: anatoliykmetyuk

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

@@ -1315,6 +1315,16 @@ trait Applications extends Compatibility {
     else if (sym1.is(Module)) compareOwner(sym1.companionClass, sym2)
     else 0
 
+  /** Drop any implicit parameter section */
+  def stripImplicit(tp: Type)(using Context): Type = tp match {
+    case mt: MethodType if mt.isImplicitMethod =>
+      stripImplicit(resultTypeApprox(mt))
+    case pt: PolyType =>
+      pt.derivedLambdaType(pt.paramNames, pt.paramInfos, stripImplicit(pt.resultType))
+    case _ =>
+      tp
+  }
+
   /** Compare to alternatives of an overloaded call or an implicit search.
    *
    *  @param  alt1, alt2      Non-overloaded references indicating the two choices
@@ -1466,16 +1476,6 @@ trait Applications extends Compatibility {
         else tp
     }
 
-    /** Drop any implicit parameter section */
-    def stripImplicit(tp: Type): Type = tp match {
-      case mt: MethodType if mt.isImplicitMethod =>
-        stripImplicit(resultTypeApprox(mt))
-      case pt: PolyType =>
-        pt.derivedLambdaType(pt.paramNames, pt.paramInfos, stripImplicit(pt.resultType))
-      case _ =>
-        tp
-    }
-
     def compareWithTypes(tp1: Type, tp2: Type) = {
       val ownerScore = compareOwner(alt1.symbol.maybeOwner, alt2.symbol.maybeOwner)
       def winsType1 = isAsSpecific(alt1, tp1, alt2, tp2)
@@ -1811,7 +1811,7 @@ trait Applications extends Compatibility {
     }
 
     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/i8188a.scala

@@ -0,0 +1,11 @@
+object Test {
+  extension StrDeco on (tree: String) {
+    def show(given DummyImplicit): String = ???
+    def show(color: Boolean)(given 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)(given DummyImplicit): String = x * 2
+  def f(x: String)(color: Boolean)(given 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)(given DummyImplicit): String = x * 2
+  def f(x: String)(given DummyImplicit)(color: Boolean): String = x * 3
+}
+
+@main def Test = println(new Foo().f("foo"))