From ec67ca07b08eebd96fb2f78c2b42bd58d28c2b2e Mon Sep 17 00:00:00 2001
From: Slava Pestov <spestov@apple.com>
Date: Fri, 14 Dec 2018 21:16:44 -0500
Subject: [PATCH 1/3] Add test case for https://bugs.swift.org/browse/SR-6739

---
 test/SILGen/default_arguments.swift | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/test/SILGen/default_arguments.swift b/test/SILGen/default_arguments.swift
index a795fa0e7e0d4..b3d86d246df7a 100644
--- a/test/SILGen/default_arguments.swift
+++ b/test/SILGen/default_arguments.swift
@@ -367,3 +367,13 @@ func callThem() throws {
    defaultEscaping()
    autoclosureDefaultEscaping()
 }
+
+func tupleDefaultArg(x: (Int, Int) = (1, 2)) {}
+
+// CHECK-LABEL: sil hidden @$s17default_arguments19callTupleDefaultArgyyF : $@convention(thin) () -> ()
+// CHECK: function_ref @$s17default_arguments15tupleDefaultArg1xySi_Sit_tFfA_ : $@convention(thin) () -> (Int, Int)
+// CHECK: function_ref @$s17default_arguments15tupleDefaultArg1xySi_Sit_tF : $@convention(thin) (Int, Int) -> ()
+// CHECK: return
+func callTupleDefaultArg() {
+  tupleDefaultArg()
+}
\ No newline at end of file

From 2c4a23c7a008d8e987960f5000bdb3512e8f5a17 Mon Sep 17 00:00:00 2001
From: Slava Pestov <spestov@apple.com>
Date: Fri, 14 Dec 2018 21:20:37 -0500
Subject: [PATCH 2/3] Add test case for https://bugs.swift.org/browse/SR-7771

---
 test/SILGen/default_arguments.swift | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/test/SILGen/default_arguments.swift b/test/SILGen/default_arguments.swift
index b3d86d246df7a..48bfaabe90c26 100644
--- a/test/SILGen/default_arguments.swift
+++ b/test/SILGen/default_arguments.swift
@@ -376,4 +376,10 @@ func tupleDefaultArg(x: (Int, Int) = (1, 2)) {}
 // CHECK: return
 func callTupleDefaultArg() {
   tupleDefaultArg()
-}
\ No newline at end of file
+}
+
+// FIXME: Should this be banned?
+func stupidGames(x: Int = 3) -> Int {
+  return x
+}
+stupidGames(x:)()
\ No newline at end of file

From 98659c697fcc0cdeab1f561a68d5ae83317bc66a Mon Sep 17 00:00:00 2001
From: Slava Pestov <spestov@apple.com>
Date: Fri, 14 Dec 2018 21:32:06 -0500
Subject: [PATCH 3/3] SILGen: Remove over-eager assertions in assignment
 lowering

We already assert that each element of the tuple is an lvalue;
asserting that the tuple itself has an lvalue or is Void is
incorrect because the tuple might have zero non-tuple elements
recursively but itself not be Void, eg ((), ()).

Fixes <https://bugs.swift.org/browse/SR-5919>.
---
 lib/SILGen/SILGenExpr.cpp    | 4 ----
 test/SILGen/assignment.swift | 9 +++++++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/lib/SILGen/SILGenExpr.cpp b/lib/SILGen/SILGenExpr.cpp
index 1700891281a2f..2cc12d0c46caf 100644
--- a/lib/SILGen/SILGenExpr.cpp
+++ b/lib/SILGen/SILGenExpr.cpp
@@ -4283,9 +4283,6 @@ namespace {
 
     // If the destination is a tuple, recursively destructure.
     void visitTupleExpr(TupleExpr *E) {
-      auto *TTy = E->getType()->castTo<TupleType>();
-      assert(TTy->hasLValueType() || TTy->isVoid());
-      (void)TTy;
       for (auto &elt : E->getElements()) {
         visit(elt);
       }
@@ -4398,7 +4395,6 @@ static void emitSimpleAssignment(SILGenFunction &SGF, SILLocation loc,
 
   // Handle tuple destinations by destructuring them if present.
   CanType destType = dest->getType()->getCanonicalType();
-  assert(!destType->isMaterializable() || destType->isVoid());
 
   // But avoid this in the common case.
   if (!isa<TupleType>(destType)) {
diff --git a/test/SILGen/assignment.swift b/test/SILGen/assignment.swift
index efd002938a612..876515654bf5c 100644
--- a/test/SILGen/assignment.swift
+++ b/test/SILGen/assignment.swift
@@ -49,3 +49,12 @@ func copyRightToLeft(p: inout P) {
   // CHECK:   end_access [[WRITE]] : $*P
   p.left = p.right
 }
+
+// SR-5919
+func stupidGames() -> ((), ()) {
+  return ((), ())
+}
+
+func assignToNestedVoid() {
+  let _: ((), ()) = stupidGames()
+}
\ No newline at end of file