[PATCH] [ms-cxxabi] Elide dtor access checks for pass-by-val objects in callees

[Hans Wennborg]

  Thanks Richard! New patch attached/uploaded that only elides the direct access check. Does this look OK?

Hi rnk, rsmith,

http://llvm-reviews.chandlerc.com/D2409

CHANGE SINCE LAST DIFF
  http://llvm-reviews.chandlerc.com/D2409?vs=6154&id=6412#toc

Files:
  lib/Sema/SemaChecking.cpp
  test/SemaCXX/microsoft-dtor-lookup.cpp
  test/SemaObjCXX/microsoft-abi-byval.mm

Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -6239,12 +6239,21 @@
 
     // MSVC destroys objects passed by value in the callee.  Therefore a
     // function definition which takes such a parameter must be able to call the
-    // object's destructor.
+    // object's destructor.  However, we don't perform any direct access check
+    // on the dtor.
     if (getLangOpts().CPlusPlus && Context.getTargetInfo()
                                        .getCXXABI()
                                        .areArgsDestroyedLeftToRightInCallee()) {
-      if (const RecordType *RT = Param->getType()->getAs<RecordType>())
-        FinalizeVarWithDestructor(Param, RT);
+      if (const RecordType *RT = Param->getType()->getAs<RecordType>()) {
+        CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(RT->getDecl());
+        if (!ClassDecl->isInvalidDecl() &&
+            !ClassDecl->hasIrrelevantDestructor() &&
+            !ClassDecl->isDependentContext()) {
+          CXXDestructorDecl *Destructor = LookupDestructor(ClassDecl);
+          MarkFunctionReferenced(Param->getLocation(), Destructor);
+          DiagnoseUseOfDecl(Destructor, Param->getLocation());
+        }
+      }
     }
   }
 
Index: test/SemaCXX/microsoft-dtor-lookup.cpp
===================================================================
--- test/SemaCXX/microsoft-dtor-lookup.cpp
+++ test/SemaCXX/microsoft-dtor-lookup.cpp
@@ -32,10 +32,9 @@
 // requires a dtor for B, but we can't implicitly define it because ~A is
 // private.  bar should be able to call A's private dtor without error, even
 // though MSVC rejects bar.
-
 class A {
 private:
-  ~A(); // expected-note 2{{declared private here}}
+  ~A(); // expected-note {{declared private here}}
   int a;
 };
 
@@ -54,7 +53,7 @@
 };
 
 void foo(B b) { } // expected-note {{implicit destructor for 'Test2::B' first required here}}
-void bar(A a) { } // expected-error {{variable of type 'Test2::A' has private destructor}}
+void bar(A a) { } // no error; MSVC rejects this, but we skip the direct access check.
 void baz(D d) { } // no error
 
 }
@@ -64,13 +63,13 @@
 
 class A {
   A();
-  ~A(); // expected-note 2{{implicitly declared private here}}
+  ~A(); // expected-note {{implicitly declared private here}}
   friend void bar(A);
   int a;
 };
 
 void bar(A a) { }
-void baz(A a) { } // expected-error {{variable of type 'Test3::A' has private destructor}}
+void baz(A a) { } // no error; MSVC rejects this, but the standard allows it.
 
 // MSVC accepts foo() but we reject it for consistency with Itanium.  MSVC also
 // rejects this if A has a copy ctor or if we call A's ctor.
Index: test/SemaObjCXX/microsoft-abi-byval.mm
===================================================================
--- test/SemaObjCXX/microsoft-abi-byval.mm
+++ test/SemaObjCXX/microsoft-abi-byval.mm
@@ -1,14 +1,15 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -cxx-abi microsoft -Wno-objc-root-class %s
+// expected-no-diagnostics
 
 class Foo {
-  ~Foo(); // expected-note {{implicitly declared private here}}
+  ~Foo();
 };
 
 @interface bar
 - (void) my_method: (Foo)arg;
 @end
 
 @implementation bar
-- (void) my_method: (Foo)arg { // expected-error {{variable of type 'Foo' has private destructor}}
+- (void) my_method: (Foo)arg { // no error; MS ABI will call Foo's dtor, but we skip the access check.
 }
 @end
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