[SILGen] Consistently call makeUsed() in RValue::getAsSingleValue().

Fixes rdar://problem/50711880.

Author: DougGregor

lib/SILGen/RValue.cpp

@@ -21,6 +21,7 @@
 #include "Initialization.h"
 #include "SILGenFunction.h"
 #include "swift/AST/CanTypeVisitor.h"
+#include "swift/Basic/Defer.h"
 #include "swift/Basic/STLExtras.h"
 #include "swift/SIL/AbstractionPattern.h"
 #include "swift/SIL/SILArgument.h"
@@ -573,19 +574,19 @@ void RValue::assignInto(SILGenFunction &SGF, SILLocation loc,
 
 ManagedValue RValue::getAsSingleValue(SILGenFunction &SGF, SILLocation loc) && {
   assert(!isUsed() && "r-value already used");
+  SWIFT_DEFER {
+    makeUsed();
+  };
 
   if (isInContext()) {
-    makeUsed();
     return ManagedValue::forInContext();
   }
 
   // Avoid killing and re-emitting the cleanup if the enclosed value isn't a
   // tuple.
   if (!isa<TupleType>(type)) {
     assert(values.size() == 1 && "exploded non-tuple?!");
-    ManagedValue result = values[0];
-    makeUsed();
-    return result;
+    return values[0];
   }
 
   // *NOTE* Inside implodeTupleValues, we copy our values if they are not at +1.

test/SILGen/property_wrappers.swift

@@ -400,6 +400,18 @@ struct ObservingTest {
   }
 }
 
+// Tuple initial values.
+struct WithTuples {
+	// CHECK-LABEL: sil hidden [ossa] @$s17property_wrappers10WithTuplesVACycfC : $@convention(method) (@thin WithTuples.Type) -> WithTuples {
+	// CHECK: function_ref @$s17property_wrappers10WithTuplesV10$fractions33_F728088E0028E14D18C6A10CF68512E8LLAA07WrapperC12InitialValueVySd_S2dtGvpfi : $@convention(thin) () -> (Double, Double, Double)
+	// CHECK: function_ref @$s17property_wrappers23WrapperWithInitialValueV07initialF0ACyxGx_tcfC : $@convention(method) <τ_0_0> (@in τ_0_0, @thin WrapperWithInitialValue<τ_0_0>.Type) -> @out WrapperWithInitialValue<τ_0_0>
+  @WrapperWithInitialValue var fractions = (1.3, 0.7, 0.3)
+
+	static func getDefault() -> WithTuples {
+		return .init()
+	}
+}
+
 // CHECK-LABEL: sil_vtable ClassUsingWrapper {
 // CHECK-NEXT:  #ClassUsingWrapper.x!getter.1: (ClassUsingWrapper) -> () -> Int : @$s17property_wrappers17ClassUsingWrapperC1xSivg   // ClassUsingWrapper.x.getter
 // CHECK-NEXT:  #ClassUsingWrapper.x!setter.1: (ClassUsingWrapper) -> (Int) -> () : @$s17property_wrappers17ClassUsingWrapperC1xSivs // ClassUsingWrapper.x.setter