[Macros] Drop the initializer when an accessor macro is applied

Author: DougGregor

lib/Sema/TypeCheckMacros.cpp

@@ -882,7 +882,24 @@ void swift::expandAccessors(
   // Trigger parsing of the sequence of accessor declarations. This has the
   // side effect of registering those accessor declarations with the storage
   // declaration, so there is nothing further to do.
-  (void)macroSourceFile->getTopLevelItems();
+  for (auto decl : macroSourceFile->getTopLevelItems()) {
+    auto accessor = dyn_cast_or_null<AccessorDecl>(decl.dyn_cast<Decl *>());
+    if (!accessor)
+      continue;
+
+    if (accessor->isObservingAccessor())
+      continue;
+
+    // If any non-observing accessor was added, remove the initializer if
+    // there is one.
+    if (auto var = dyn_cast<VarDecl>(storage)) {
+      if (auto binding = var->getParentPatternBinding()) {
+        unsigned index = binding->getPatternEntryIndexForVarDecl(var);
+        binding->setInit(index, nullptr);
+        break;
+      }
+    }
+  }
 }
 
 // FIXME: Almost entirely duplicated code from `expandAccessors`.

test/Macros/accessor_macros.swift

@@ -2,7 +2,7 @@
 // RUN: %target-build-swift -I %swift-host-lib-dir -L %swift-host-lib-dir -emit-library -o %t/%target-library-name(MacroDefinition) -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift -g -no-toolchain-stdlib-rpath
 
 // First check for no errors.
-// RUN: %target-typecheck-verify-swift -enable-experimental-feature Macros -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir %s
+// RUN: %target-typecheck-verify-swift -enable-experimental-feature Macros -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir
 
 // Check that the expansion buffer are as expected.
 // RUN: %target-swift-frontend -typecheck -enable-experimental-feature Macros -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir %s -dump-macro-expansions > %t/expansions-dump.txt 2>&1
@@ -53,7 +53,7 @@ struct MyStruct {
   // CHECK-DUMP: }
 
   @myPropertyWrapper
-  var birthDate: Date?
+  var birthDate: Date? = nil
   // CHECK-DUMP: macro:birthDate@myPropertyWrapper
   // CHECK-DUMP: get {
   // CHECK-DUMP:   _birthDate.wrappedValue