SIL: Fix assertion failure when function with opaque result type returns a tuple

Author: slavapestov

lib/SIL/AbstractionPattern.cpp

@@ -274,11 +274,16 @@ bool AbstractionPattern::matchesTuple(CanTupleType substType) {
     return getNumTupleElements_Stored() == substType->getNumElements();
   case Kind::ClangType:
   case Kind::Type:
-  case Kind::Discard:
+  case Kind::Discard: {
     if (isTypeParameter())
       return true;
-    auto tuple = dyn_cast<TupleType>(getType());
-    return (tuple && tuple->getNumElements() == substType->getNumElements());
+    auto type = getType();
+    if (auto tuple = dyn_cast<TupleType>(type))
+      return (tuple->getNumElements() == substType->getNumElements());
+    if (isa<OpaqueTypeArchetypeType>(type))
+      return true;
+    return false;
+  }
   }
   llvm_unreachable("bad kind");
 }

test/SILGen/opaque_result_type.swift

@@ -165,3 +165,11 @@ public class D {
         return d
     }()
 }
+
+// CHECK-LABEL: sil [ossa] @$s18opaque_result_type10tupleAsAnyQryF : $@convention(thin) () -> @out @_opaqueReturnTypeOf("$s18opaque_result_type10tupleAsAnyQryF", 0) 🦸 {
+public func tupleAsAny() -> some Any {
+// CHECK-NEXT: bb0(%0 : $*()):
+// CHECK-NEXT:   %1 = tuple ()
+// CHECK-NEXT:   return %1 : $()
+  return ()
+}