make exec::finally pipeable again; fixes #1842

Author: ericniebler

include/exec/finally.hpp

@@ -21,6 +21,7 @@
 // include these after execution_fwd.hpp
 #include "../stdexec/__detail/__basic_sender.hpp"
 #include "../stdexec/__detail/__optional.hpp"
+#include "../stdexec/__detail/__sender_adaptor_closure.hpp"
 #include "../stdexec/__detail/__senders.hpp"
 #include "../stdexec/__detail/__tuple.hpp"
 #include "../stdexec/__detail/__utility.hpp"
@@ -48,7 +49,7 @@ namespace exec {
     template <STDEXEC::sender _Final>
     STDEXEC_ATTRIBUTE(always_inline)
     auto operator()(_Final&& __final) const {
-      return __closure(*this, static_cast<_Final&&>(__final));
+      return STDEXEC::__closure(*this, static_cast<_Final&&>(__final));
     }
 
     template <class _Sender>

test/exec/test_finally.cpp

@@ -28,6 +28,11 @@ namespace {
     STATIC_REQUIRE(sender<decltype(s)>);
   }
 
+  TEST_CASE("finally with pipe syntax is a sender", "[adaptors][finally]") {
+    auto s = just() | exec::finally(just());
+    STATIC_REQUIRE(sender<decltype(s)>);
+  }
+
   TEST_CASE("finally is a sender in empty env", "[adaptors][finally]") {
     auto s = exec::finally(just(), just());
     STATIC_REQUIRE(sender_in<decltype(s), ex::env<>>);