Partial fix for PR7267 based on comments by John McCall on an earlier patch.

This is more targeted, as it simply provides toggle actions for the parser to
turn access checking on and off. We then use these to suppress access checking
only while we parse the template-id (included scope specifier) of an explicit
instantiation and explicit specialization of a class template. The
specialization behavior is an extension, as it seems likely a defect that the
standard did not exempt them as it does explicit instantiations.

This allows the very common practice of specializing trait classes to work for
private, internal types. This doesn't address instantiating or specializing
function templates, although those apparently already partially work.

The naming and style for the Action layer isn't my favorite, comments and
suggestions would be appreciated there.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@106993 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Parse/Action.h b/include/clang/Parse/Action.h
index d8bb8a5b6158c335dc4c87f299c74436c9a22d5a..fed4361f1ae5c9cf9b3f8b7e848663a98ba3d910 100644 (file)
--- a/include/clang/Parse/Action.h
+++ b/include/clang/Parse/Action.h
@@ -2278,6 +2278,16 @@ public:
     return TypeResult();
   }
 
+  /// \brief Called when the parser begins parsing a construct which should not
+  /// have access control applied to it.
+  virtual void ActOnStartSuppressingAccessChecks() {
+  }
+
+  /// \brief Called when the parser finishes parsing a construct which should
+  /// not have access control applied to it.
+  virtual void ActOnStopSuppressingAccessChecks() {
+  }
+
   //===----------------------- Obj-C Declarations -------------------------===//
 
   // ActOnStartClassInterface - this action is called immediately after parsing

diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index 53fc3405bb3c4c537338bbafc2f16af809ed04b9..ffef288e71e0e44425150569b1ad2288e84a96f6 100644 (file)
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -613,6 +613,20 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     ConsumeCodeCompletionToken();
   }
 
+  // C++03 [temp.explicit] 14.7.2/8:
+  //   The usual access checking rules do not apply to names used to specify
+  //   explicit instantiations.
+  //
+  // As an extension we do not perform access checking on the names used to
+  // specify explicit specializations either. This is important to allow
+  // specializing traits classes for private types.
+  bool SuppressingAccessChecks = false;
+  if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
+      TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization) {
+    Actions.ActOnStartSuppressingAccessChecks();
+    SuppressingAccessChecks = true;
+  }
+
   AttributeList *AttrList = 0;
   // If attributes exist after tag, parse them.
   if (Tok.is(tok::kw___attribute))
@@ -732,10 +746,18 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
       DS.SetTypeSpecError();
       SkipUntil(tok::semi, false, true);
       TemplateId->Destroy();
+      if (SuppressingAccessChecks)
+        Actions.ActOnStopSuppressingAccessChecks();
+
       return;
     }
   }
 
+  // As soon as we're finished parsing the class's template-id, turn access
+  // checking back on.
+  if (SuppressingAccessChecks)
+    Actions.ActOnStopSuppressingAccessChecks();
+
   // There are four options here.  If we have 'struct foo;', then this
   // is either a forward declaration or a friend declaration, which
   // have to be treated differently.  If we have 'struct foo {...' or

diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index eadc2ad253d82a8f62241a05e57bc8d210a79215..d520a78abec2c47d74839735d54590cb766ef3c3 100644 (file)
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -125,8 +125,8 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     IdResolver(pp.getLangOptions()), StdNamespace(0), StdBadAlloc(0),
     GlobalNewDeleteDeclared(false), 
     CompleteTranslationUnit(CompleteTranslationUnit),
-    NumSFINAEErrors(0), NonInstantiationEntries(0), 
-    CurrentInstantiationScope(0), TyposCorrected(0),
+    NumSFINAEErrors(0), SuppressAccessChecking(false),
+    NonInstantiationEntries(0), CurrentInstantiationScope(0), TyposCorrected(0),
     AnalysisWarnings(*this)
 {
   TUScope = 0;

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 9d5e290b2f66f87c26140f1e9ecdba291b5d0cdd..fcf5e94149f52dcf81c8aff1ba2d444af2fcd3f5 100644 (file)
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -2797,6 +2797,12 @@ public:
 
   void HandleDelayedAccessCheck(DelayedDiagnostic &DD, Decl *Ctx);
 
+  /// A flag to suppress access checking.
+  bool SuppressAccessChecking;
+
+  void ActOnStartSuppressingAccessChecks();
+  void ActOnStopSuppressingAccessChecks();
+
   enum AbstractDiagSelID {
     AbstractNone = -1,
     AbstractReturnType,

diff --git a/lib/Sema/SemaAccess.cpp b/lib/Sema/SemaAccess.cpp
index 7845f6d0a94a8c254194dcd62a09c41d83293c34..e110e3dfa47139e9c0d1543cb679fe2046e63e07 100644 (file)
--- a/lib/Sema/SemaAccess.cpp
+++ b/lib/Sema/SemaAccess.cpp
@@ -1024,6 +1024,9 @@ static Sema::AccessResult CheckAccess(Sema &S, SourceLocation Loc,
   if (Entity.getAccess() == AS_public)
     return Sema::AR_accessible;
 
+  if (S.SuppressAccessChecking)
+    return Sema::AR_accessible;
+
   // If we're currently parsing a top-level declaration, delay
   // diagnostics.  This is the only case where parsing a declaration
   // can actually change our effective context for the purposes of
@@ -1334,3 +1337,15 @@ void Sema::CheckLookupAccess(const LookupResult &R) {
     }
   }
 }
+
+void Sema::ActOnStartSuppressingAccessChecks() {
+  assert(!SuppressAccessChecking &&
+         "Tried to start access check suppression when already started.");
+  SuppressAccessChecking = true;
+}
+
+void Sema::ActOnStopSuppressingAccessChecks() {
+  assert(SuppressAccessChecking &&
+         "Tried to stop access check suprression when already stopped.");
+  SuppressAccessChecking = false;
+}

diff --git a/test/CXX/temp/temp.spec/temp.explicit/p11.cpp b/test/CXX/temp/temp.spec/temp.explicit/p11.cpp
new file mode 100644 (file)
index 0000000..4ca5428
--- /dev/null
+++ b/test/CXX/temp/temp.spec/temp.explicit/p11.cpp
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+class X {
+  template <typename T> class Y {};
+};
+
+class A {
+  class B {};
+  class C {};
+};
+
+// C++0x [temp.explicit] 14.7.2/11:
+//   The usual access checking rules do not apply to names used to specify
+//   explicit instantiations.
+template class X::Y<A::B>;
+
+// As an extension, this rule is applied to explicit specializations as well.
+template <> class X::Y<A::C> {};