[PropertyWrappers] lvalue computation in buildStorageReference() should use PropertyWrapperMutability

Author: theblixguy

lib/Sema/TypeCheckStorage.cpp

@@ -738,10 +738,12 @@ static Expr *buildStorageReference(AccessorDecl *accessor,
 
   // If we're acessing a property wrapper, determine if the
   // intermediate access requires an lvalue.
-  if (underlyingVars.size() > 0) {
-    isMemberLValue = underlyingVars[0]->isGetterMutating();
-    if (isLValue)
-      isMemberLValue |= underlyingVars[0]->isSetterMutating();
+  if (auto var = dyn_cast<VarDecl>(accessor->getStorage())) {
+    if (auto mut = var->getPropertyWrapperMutability()) {
+      isMemberLValue = mut->Getter == PropertyWrapperMutability::Mutating;
+      if (isLValue)
+        isMemberLValue |= mut->Setter == PropertyWrapperMutability::Mutating;
+    }
   }
 
   bool isSelfLValue = storage->isGetterMutating();

test/SILGen/property_wrappers.swift

@@ -519,6 +519,30 @@ extension UsesMyPublished {
   }
 }
 
+// SR-11603 - crash due to incorrect lvalue computation
+@propertyWrapper
+struct StructWrapper<T> {
+  var wrappedValue: T
+}
+
+@propertyWrapper
+class ClassWrapper<T> {
+  var wrappedValue: T
+  init(wrappedValue: T) {
+    self.wrappedValue = wrappedValue
+  }
+}
+
+
+struct SR_11603 {
+  // CHECK: @StructWrapper @ClassWrapper var prop: Int { get nonmutating set }
+  @StructWrapper @ClassWrapper var prop: Int
+
+  func foo() {
+    prop = 1234
+  }
+}
+
 // 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