Add documentation and test for indirect summons

Author: jchyb

Diff for: library/src/scala/quoted/Expr.scala

@@ -280,6 +280,17 @@ object Expr {
     }
   }
 
+  /** Find a given instance of type `T` in the current scope,
+   *  while excluding certain symbols from the initial implicit search.
+   *  Return `Some` containing the expression of the implicit or
+   * `None` if implicit resolution failed.
+   *
+   *  @tparam T type of the implicit parameter
+   *  @param ignored Symbols ignored during the initial implicit search
+   *
+   *  @note if the found given requires additional search for other given instances,
+   *  this additional search will NOT exclude the symbols from the `ignored` list.
+   */
   @scala.annotation.experimental def summonIgnoring[T](using Type[T])(using quotes: Quotes)(ignored: quotes.reflect.Symbol*): Option[Expr[T]] = {
     import quotes.reflect._
     Implicits.searchIgnoring(TypeRepr.of[T])(ignored*) match {

Diff for: library/src/scala/quoted/Quotes.scala

@@ -3706,6 +3706,16 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       */
       def search(tpe: TypeRepr): ImplicitSearchResult
 
+      /** Find a given instance of type `T` in the current scope provided by the current enclosing splice,
+      *  while excluding certain symbols from the initial implicit search.
+      *  Return an `ImplicitSearchResult`.
+      *
+      *  @param tpe type of the implicit parameter
+      *  @param ignored Symbols ignored during the initial implicit search
+      *
+      *  @note if an found given requires additional search for other given instances,
+      *  this additional search will NOT exclude the symbols from the `ignored` list.
+      */
       @experimental def searchIgnoring(tpe: TypeRepr)(ignored: Symbol*): ImplicitSearchResult
     }
 

Diff for: tests/run-macros/summonIgnoring-nonrecursive.check

@@ -0,0 +1,3 @@
+TC[C2] generated in macro using:
+TC2[_] generated in macro using:
+TC[C1] generated in macro

Diff for: tests/run-macros/summonIgnoring-nonrecursive/Macro_1.scala

@@ -0,0 +1,50 @@
+//> using options -experimental
+import scala.quoted._
+class C1
+trait TC[T] {
+  def print(): Unit
+}
+
+object TC {
+  implicit transparent inline def auto[T]: TC[T] = ${autoImpl[T]}
+  def autoImpl[T: Type](using Quotes): Expr[TC[T]] =
+    import quotes.reflect._
+    if (TypeRepr.of[T].typeSymbol == Symbol.classSymbol("C1")){
+      '{
+        new TC[T] {
+          def print() = {
+            println("TC[C1] generated in macro")
+          }
+        }
+      }
+    } else {
+      Expr.summonIgnoring[TC2[C1]](Symbol.classSymbol("TC").companionModule.methodMember("auto")*) match
+        case Some(a) =>
+          '{
+            new TC[T] {
+              def print(): Unit =
+                println(s"TC[${${Expr(TypeRepr.of[T].show)}}] generated in macro using:")
+                $a.print()
+            }
+          }
+        case None =>
+          '{
+            new TC[T]{
+              def print(): Unit =
+                println(s"TC[${${Expr(TypeRepr.of[T].show)}}] generated in macro without TC2[_]")
+            }
+          }
+    }
+}
+
+trait TC2[T] {
+  def print(): Unit
+}
+
+object TC2 {
+  implicit def auto2[T](using tc: TC[T]): TC2[T] = new TC2[T] {
+    def print(): Unit =
+      println(s"TC2[_] generated in macro using:")
+      tc.print()
+  }
+}

Diff for: tests/run-macros/summonIgnoring-nonrecursive/Test_2.scala

@@ -0,0 +1,6 @@
+//> using options -experimental
+
+@main def Test(): Unit = {
+  class C2
+  summon[TC[C2]].print()
+}