Change how we suppress access control in explicit instantiations

so that we actually accumulate all the delayed diagnostics.  Do
this so that we can restore those diagnostics to good standing
if it turns out that we were wrong to suppress, e.g. if the
tag specifier is actually an elaborated type specifier and not
a declaration.

llvm-svn: 156291

6 files changed, 122 insertions, 45 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index dbf35b14cfb..7cb64746781 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2773,12 +2773,16 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     ScopedEnumKWLoc = ConsumeToken();
   }
 
-  // C++11 [temp.explicit]p12: The usual access controls do not apply to names
-  // used to specify explicit instantiations. We extend this to also cover
-  // explicit specializations.
-  Sema::SuppressAccessChecksRAII SuppressAccess(Actions,
-    TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
-    TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);
+  // C++11 [temp.explicit]p12:
+  //   The usual access controls do not apply to names used to specify
+  //   explicit instantiations.
+  // We extend this to also cover explicit specializations.  Note that
+  // we don't suppress if this turns out to be an elaborated type
+  // specifier.
+  bool shouldDelayDiagsInTag =
+    (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
+     TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);
+  SuppressAccessChecks diagsFromTag(*this, shouldDelayDiagsInTag);
 
   // If attributes exist after tag, parse them.
   ParsedAttributes attrs(AttrFactory);
@@ -2842,8 +2846,10 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     IsScopedUsingClassTag = false;
   }
 
-  // Stop suppressing access control now we've parsed the enum name.
-  SuppressAccess.done();
+  // Okay, end the suppression area.  We'll decide whether to emit the
+  // diagnostics in a second.
+  if (shouldDelayDiagsInTag)
+    diagsFromTag.done();
 
   TypeResult BaseType;
 
@@ -2925,16 +2931,29 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   // enum foo {..};  void bar() { enum foo x; }  <- use of old foo.
   //
   Sema::TagUseKind TUK;
-  if (DS.isFriendSpecified())
-    TUK = Sema::TUK_Friend;
-  else if (!AllowDeclaration)
+  if (!AllowDeclaration) {
     TUK = Sema::TUK_Reference;
-  else if (Tok.is(tok::l_brace))
-    TUK = Sema::TUK_Definition;
-  else if (Tok.is(tok::semi) && DSC != DSC_type_specifier)
-    TUK = Sema::TUK_Declaration;
-  else
+  } else if (Tok.is(tok::l_brace)) {
+    if (DS.isFriendSpecified()) {
+      Diag(Tok.getLocation(), diag::err_friend_decl_defines_type)
+        << SourceRange(DS.getFriendSpecLoc());
+      ConsumeBrace();
+      SkipUntil(tok::r_brace);
+      TUK = Sema::TUK_Friend;
+    } else {
+      TUK = Sema::TUK_Definition;
+    }
+  } else if (Tok.is(tok::semi) && DSC != DSC_type_specifier) {
+    TUK = (DS.isFriendSpecified() ? Sema::TUK_Friend : Sema::TUK_Declaration);
+  } else {
     TUK = Sema::TUK_Reference;
+  }
+
+  // If this is an elaborated type specifier, and we delayed
+  // diagnostics before, just merge them into the current pool.
+  if (TUK == Sema::TUK_Reference && shouldDelayDiagsInTag) {
+    diagsFromTag.redelay();
+  }
 
   MultiTemplateParamsArg TParams;
   if (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
@@ -3014,14 +3033,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   }
 
   if (Tok.is(tok::l_brace) && TUK != Sema::TUK_Reference) {
-    if (TUK == Sema::TUK_Friend) {
-      Diag(Tok, diag::err_friend_decl_defines_type)
-        << SourceRange(DS.getFriendSpecLoc());
-      ConsumeBrace();
-      SkipUntil(tok::r_brace);
-    } else {
-      ParseEnumBody(StartLoc, TagDecl);
-    }
+    ParseEnumBody(StartLoc, TagDecl);
   }
 
   if (DS.SetTypeSpecType(DeclSpec::TST_enum, StartLoc,
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 2a641413536..730c345d807 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -968,9 +968,13 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   // 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.
-  Sema::SuppressAccessChecksRAII SuppressAccess(Actions,
-    TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
-    TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);
+  //
+  // Note that we don't suppress if this turns out to be an elaborated
+  // type specifier.
+  bool shouldDelayDiagsInTag =
+    (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
+     TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);
+  SuppressAccessChecks diagsFromTag(*this, shouldDelayDiagsInTag);
 
   ParsedAttributes attrs(AttrFactory);
   // If attributes exist after tag, parse them.
@@ -1103,10 +1107,6 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
     }
   }
 
-  // As soon as we're finished parsing the class's template-id, turn access
-  // checking back on.
-  SuppressAccess.done();
-
   // There are four options here.
   //  - If we are in a trailing return type, this is always just a reference,
   //    and we must not try to parse a definition. For instance,
@@ -1149,6 +1149,14 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   else
     TUK = Sema::TUK_Reference;
 
+  // If this is an elaborated type specifier, and we delayed
+  // diagnostics before, just merge them into the current pool.
+  if (shouldDelayDiagsInTag) {
+    diagsFromTag.done();
+    if (TUK == Sema::TUK_Reference)
+      diagsFromTag.redelay();
+  }
+
   if (!Name && !TemplateId && (DS.getTypeSpecType() == DeclSpec::TST_error ||
                                TUK != Sema::TUK_Definition)) {
     if (DS.getTypeSpecType() != DeclSpec::TST_error) {
diff --git a/clang/lib/Parse/RAIIObjectsForParser.h b/clang/lib/Parse/RAIIObjectsForParser.h
index f5a6f8fcf94..64431276bf7 100644
--- a/clang/lib/Parse/RAIIObjectsForParser.h
+++ b/clang/lib/Parse/RAIIObjectsForParser.h
@@ -24,6 +24,59 @@ namespace clang {
   // TODO: move ParsingClassDefinition here.
   // TODO: move TentativeParsingAction here.
 
+  /// \brief A RAII object used to temporarily suppress access-like
+  /// checking.  Access-like checks are those associated with
+  /// controlling the use of a declaration, like C++ access control
+  /// errors and deprecation warnings.  They are contextually
+  /// dependent, in that they can only be resolved with full
+  /// information about what's being declared.  They are also
+  /// suppressed in certain contexts, like the template arguments of
+  /// an explicit instantiation.  However, those suppression contexts
+  /// cannot necessarily be fully determined in advance;  for
+  /// example, something starting like this:
+  ///   template <> class std::vector<A::PrivateType>
+  /// might be the entirety of an explicit instantiation:
+  ///   template <> class std::vector<A::PrivateType>;
+  /// or just an elaborated type specifier:
+  ///   template <> class std::vector<A::PrivateType> make_vector<>();
+  /// Therefore this class collects all the diagnostics and permits
+  /// them to be re-delayed in a new context.
+  class SuppressAccessChecks {
+    Sema &S;
+    sema::DelayedDiagnosticPool DiagnosticPool;
+    Sema::ParsingDeclState State;
+    bool Active;
+
+  public:
+    /// Begin suppressing access-like checks 
+    SuppressAccessChecks(Parser &P, bool activate = true)
+        : S(P.getActions()), DiagnosticPool(NULL) {
+      if (activate) {
+        State = S.PushParsingDeclaration(DiagnosticPool);
+        Active = true;
+      } else {
+        Active = false;
+      }
+    }
+
+    void done() {
+      assert(Active && "trying to end an inactive suppression");
+      S.PopParsingDeclaration(State, NULL);
+      Active = false;
+    }
+
+    void redelay() {
+      assert(!Active && "redelaying without having ended first");
+      if (!DiagnosticPool.pool_empty())
+        S.redelayDiagnostics(DiagnosticPool);
+      assert(DiagnosticPool.pool_empty());
+    }
+
+    ~SuppressAccessChecks() {
+      if (Active) done();
+    }
+  };
+
   /// \brief RAII object used to inform the actions that we're
   /// currently parsing a declaration.  This is active when parsing a
   /// variable's initializer, but not when parsing the body of a
@@ -93,14 +146,13 @@ namespace clang {
       pop(D);
     }
 
-  private:
-    void steal(ParsingDeclRAIIObject &Other) {
-      DiagnosticPool.steal(Other.DiagnosticPool);
-      State = Other.State;
-      Popped = Other.Popped;
-      Other.Popped = true;
+    /// Unregister this object from Sema, but remember all the
+    /// diagnostics that were emitted into it.
+    void abortAndRemember() {
+      pop(0);
     }
 
+  private:
     void push() {
       State = Actions.PushParsingDeclaration(DiagnosticPool);
       Popped = false;
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index ca3e233cb7e..5017c2cdf56 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -99,7 +99,7 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     ObjCShouldCallSuperDealloc(false),
     ObjCShouldCallSuperFinalize(false),
     TUKind(TUKind),
-    NumSFINAEErrors(0), InFunctionDeclarator(0), SuppressAccessChecking(false), 
+    NumSFINAEErrors(0), InFunctionDeclarator(0),
     AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
     NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
     CurrentInstantiationScope(0), TyposCorrected(0),
diff --git a/clang/lib/Sema/SemaAccess.cpp b/clang/lib/Sema/SemaAccess.cpp
index 13bb6dc7dbb..49e59001d2f 100644
--- a/clang/lib/Sema/SemaAccess.cpp
+++ b/clang/lib/Sema/SemaAccess.cpp
@@ -1391,9 +1391,6 @@ 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 declaration, we may need to delay
   // access control checking, because our effective context might be
   // different based on what the declaration comes out as.
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index e3a21694ac8..f2d1d19d22d 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4200,8 +4200,7 @@ static void handleDelayedForbiddenType(Sema &S, DelayedDiagnostic &diag,
 
 void Sema::PopParsingDeclaration(ParsingDeclState state, Decl *decl) {
   assert(DelayedDiagnostics.getCurrentPool());
-  sema::DelayedDiagnosticPool &poppedPool =
-    *DelayedDiagnostics.getCurrentPool();
+  DelayedDiagnosticPool &poppedPool = *DelayedDiagnostics.getCurrentPool();
   DelayedDiagnostics.popWithoutEmitting(state);
 
   // When delaying diagnostics to run in the context of a parsed
@@ -4216,9 +4215,9 @@ void Sema::PopParsingDeclaration(ParsingDeclState state, Decl *decl) {
   // only the declarator pops will be passed decls.  This is correct;
   // we really do need to consider delayed diagnostics from the decl spec
   // for each of the different declarations.
-  const sema::DelayedDiagnosticPool *pool = &poppedPool;
+  const DelayedDiagnosticPool *pool = &poppedPool;
   do {
-    for (sema::DelayedDiagnosticPool::pool_iterator
+    for (DelayedDiagnosticPool::pool_iterator
            i = pool->pool_begin(), e = pool->pool_end(); i != e; ++i) {
       // This const_cast is a bit lame.  Really, Triggered should be mutable.
       DelayedDiagnostic &diag = const_cast<DelayedDiagnostic&>(*i);
@@ -4244,6 +4243,15 @@ void Sema::PopParsingDeclaration(ParsingDeclState state, Decl *decl) {
   } while ((pool = pool->getParent()));
 }
 
+/// Given a set of delayed diagnostics, re-emit them as if they had
+/// been delayed in the current context instead of in the given pool.
+/// Essentially, this just moves them to the current pool.
+void Sema::redelayDiagnostics(DelayedDiagnosticPool &pool) {
+  DelayedDiagnosticPool *curPool = DelayedDiagnostics.getCurrentPool();
+  assert(curPool && "re-emitting in undelayed context not supported");
+  curPool->steal(pool);
+}
+
 static bool isDeclDeprecated(Decl *D) {
   do {
     if (D->isDeprecated())