When we form a new function/class template specialization, we first

search for the specialization (in a folding set) and, if not found
form a *Decl that is then inserted into that folding set. In rare
cases, the folding set may be reallocated between the search and the
insertion, causing a crash. No test case, because triggering rehashing
consistently in a small test case is not feasible. Fixes
<rdar://problem/11115071>.

llvm-svn: 153575

clang/lib/AST/Decl.cpp

@@ -2255,22 +2255,7 @@ FunctionDecl::setFunctionTemplateSpecialization(ASTContext &C,
                                                       TemplateArgsAsWritten,
                                                       PointOfInstantiation);
   TemplateOrSpecialization = Info;
-
+  Template->addSpecialization(Info, InsertPos);
-  // Insert this function template specialization into the set of known
-  // function template specializations.
-  if (InsertPos)
-    Template->addSpecialization(Info, InsertPos);
-  else {
-    // Try to insert the new node. If there is an existing node, leave it, the
-    // set will contain the canonical decls while
-    // FunctionTemplateDecl::findSpecialization will return
-    // the most recent redeclarations.
-    FunctionTemplateSpecializationInfo *Existing
-      = Template->getSpecializations().GetOrInsertNode(Info);
-    (void)Existing;
-    assert((!Existing || Existing->Function->isCanonicalDecl()) &&
-           "Set is supposed to only contain canonical decls");
-  }
 }
 
 void

clang/lib/AST/DeclTemplate.cpp

@@ -238,7 +238,10 @@ FunctionTemplateDecl::findSpecialization(const TemplateArgument *Args,
 
 void FunctionTemplateDecl::addSpecialization(
       FunctionTemplateSpecializationInfo *Info, void *InsertPos) {
-  getSpecializations().InsertNode(Info, InsertPos);
+  if (InsertPos)
+    getSpecializations().InsertNode(Info, InsertPos);
+  else
+    getSpecializations().GetOrInsertNode(Info);
   if (ASTMutationListener *L = getASTMutationListener())
     L->AddedCXXTemplateSpecialization(this, Info->Function);
 }
@@ -322,7 +325,14 @@ ClassTemplateDecl::findSpecialization(const TemplateArgument *Args,
 
 void ClassTemplateDecl::AddSpecialization(ClassTemplateSpecializationDecl *D,
                                           void *InsertPos) {
-  getSpecializations().InsertNode(D, InsertPos);
+  if (InsertPos)
+    getSpecializations().InsertNode(D, InsertPos);
+  else {
+    ClassTemplateSpecializationDecl *Existing 
+      = getSpecializations().GetOrInsertNode(D);
+    (void)Existing;
+    assert(Existing->isCanonicalDecl() && "Non-canonical specialization?");
+  }
   if (ASTMutationListener *L = getASTMutationListener())
     L->AddedCXXTemplateSpecialization(this, D);
 }
@@ -338,7 +348,15 @@ ClassTemplateDecl::findPartialSpecialization(const TemplateArgument *Args,
 void ClassTemplateDecl::AddPartialSpecialization(
                                       ClassTemplatePartialSpecializationDecl *D,
                                       void *InsertPos) {
-  getPartialSpecializations().InsertNode(D, InsertPos);
+  if (InsertPos)
+    getPartialSpecializations().InsertNode(D, InsertPos);
+  else {
+    ClassTemplatePartialSpecializationDecl *Existing
+      = getPartialSpecializations().GetOrInsertNode(D);
+    (void)Existing;
+    assert(Existing->isCanonicalDecl() && "Non-canonical specialization?");
+  }
+
   if (ASTMutationListener *L = getASTMutationListener())
     L->AddedCXXTemplateSpecialization(this, D);
 }

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -1014,11 +1014,11 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
   // Check whether there is already a function template specialization for
   // this declaration.
   FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
-  void *InsertPos = 0;
   if (FunctionTemplate && !TemplateParams) {
     std::pair<const TemplateArgument *, unsigned> Innermost
       = TemplateArgs.getInnermost();
 
+    void *InsertPos = 0;
     FunctionDecl *SpecFunc
       = FunctionTemplate->findSpecialization(Innermost.first, Innermost.second,
                                              InsertPos);
@@ -1148,7 +1148,7 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
                             TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                              Innermost.first,
                                                              Innermost.second),
-                                                InsertPos);
+                                                /*InsertPos=*/0);
   } else if (isFriend) {
     // Note, we need this connection even if the friend doesn't have a body.
     // Its body may exist but not have been attached yet due to deferred
@@ -1316,7 +1316,6 @@ TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D,
                                       TemplateParameterList *TemplateParams,
                                       bool IsClassScopeSpecialization) {
   FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
-  void *InsertPos = 0;
   if (FunctionTemplate && !TemplateParams) {
     // We are creating a function template specialization from a function
     // template. Check whether there is already a function template
@@ -1324,6 +1323,7 @@ TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D,
     std::pair<const TemplateArgument *, unsigned> Innermost
       = TemplateArgs.getInnermost();
 
+    void *InsertPos = 0;
     FunctionDecl *SpecFunc
       = FunctionTemplate->findSpecialization(Innermost.first, Innermost.second,
                                              InsertPos);
@@ -1476,7 +1476,7 @@ TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D,
                          TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                           Innermost.first,
                                                           Innermost.second),
-                                              InsertPos);
+                                              /*InsertPos=*/0);
   } else if (!isFriend) {
     // Record that this is an instantiation of a member function.
     Method->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
@@ -2125,7 +2125,7 @@ TemplateDeclInstantiator::InstantiateClassTemplatePartialSpecialization(
 
   // Add this partial specialization to the set of class template partial
   // specializations.
-  ClassTemplate->AddPartialSpecialization(InstPartialSpec, InsertPos);
+  ClassTemplate->AddPartialSpecialization(InstPartialSpec, /*InsertPos=*/0);
   return InstPartialSpec;
 }