[ASTImporter] Improved import of friend templates.

Summary:
When importing a friend class template declaration,
this declaration should not be merged with any other existing declaration
for the same type. Otherwise the getFriendDecl of the FriendDecl can point
to an other already referenced declaration, this case causes problems.
Additionally the previous decl of class templates is set at import.

Reviewers: a.sidorin, a_sidorin

Reviewed By: a_sidorin

Subscribers: a_sidorin, martong, cfe-commits

Differential Revision: https://reviews.llvm.org/D50516

llvm-svn: 339560

1 files changed, 36 insertions, 10 deletions

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 768b2e5bedb..c1136c9f428 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -2164,11 +2164,21 @@ Decl *ASTNodeImporter::VisitEnumDecl(EnumDecl *D) {
 }
 
 Decl *ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
+  bool IsFriendTemplate = false;
+  if (auto *DCXX = dyn_cast<CXXRecordDecl>(D)) {
+    IsFriendTemplate =
+        DCXX->getDescribedClassTemplate() &&
+        DCXX->getDescribedClassTemplate()->getFriendObjectKind() !=
+            Decl::FOK_None;
+  }
+
   // If this record has a definition in the translation unit we're coming from,
   // but this particular declaration is not that definition, import the
   // definition and map to that.
   TagDecl *Definition = D->getDefinition();
   if (Definition && Definition != D &&
+      // Friend template declaration must be imported on its own.
+      !IsFriendTemplate &&
       // In contrast to a normal CXXRecordDecl, the implicit
       // CXXRecordDecl of ClassTemplateSpecializationDecl is its redeclaration.
       // The definition of the implicit CXXRecordDecl in this case is the
@@ -2241,7 +2251,7 @@ Decl *ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
         PrevDecl = FoundRecord;
 
         if (RecordDecl *FoundDef = FoundRecord->getDefinition()) {
-          if ((SearchName && !D->isCompleteDefinition())
+          if ((SearchName && !D->isCompleteDefinition() && !IsFriendTemplate)
               || (D->isCompleteDefinition() &&
                   D->isAnonymousStructOrUnion()
                     == FoundDef->isAnonymousStructOrUnion() &&
@@ -2281,6 +2291,9 @@ Decl *ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
               !IsStructuralMatch(D, FoundRecord))
             continue;
 
+          if (IsFriendTemplate)
+            continue;
+
           AdoptDecl = FoundRecord;
           continue;
         } else if (!SearchName) {
@@ -2348,7 +2361,7 @@ Decl *ASTNodeImporter::VisitRecordDecl(RecordDecl *D) {
         if (!ToDescribed)
           return nullptr;
         D2CXX->setDescribedClassTemplate(ToDescribed);
-        if (!DCXX->isInjectedClassName()) {
+        if (!DCXX->isInjectedClassName() && !IsFriendTemplate) {
           // In a record describing a template the type should be an
           // InjectedClassNameType (see Sema::CheckClassTemplate). Update the
           // previously set type to the correct value here (ToDescribed is not
@@ -4371,12 +4384,14 @@ static ClassTemplateDecl *getDefinition(ClassTemplateDecl *D) {
 }
 
 Decl *ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
+  bool IsFriend = D->getFriendObjectKind() != Decl::FOK_None;
+
   // If this record has a definition in the translation unit we're coming from,
   // but this particular declaration is not that definition, import the
   // definition and map to that.
   auto *Definition =
       cast_or_null<CXXRecordDecl>(D->getTemplatedDecl()->getDefinition());
-  if (Definition && Definition != D->getTemplatedDecl()) {
+  if (Definition && Definition != D->getTemplatedDecl() && !IsFriend) {
     Decl *ImportedDef
       = Importer.Import(Definition->getDescribedClassTemplate());
     if (!ImportedDef)
@@ -4413,17 +4428,20 @@ Decl *ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
           // definition. So, try to get the definition if that is available in
           // the redecl chain.
           ClassTemplateDecl *TemplateWithDef = getDefinition(FoundTemplate);
-          if (!TemplateWithDef)
+          if (TemplateWithDef)
+            FoundTemplate = TemplateWithDef;
+          else
             continue;
-          FoundTemplate = TemplateWithDef; // Continue with the definition.
         }
 
         if (IsStructuralMatch(D, FoundTemplate)) {
-          // The class templates structurally match; call it the same template.
+          if (!IsFriend) {
+            Importer.MapImported(D->getTemplatedDecl(),
+                                 FoundTemplate->getTemplatedDecl());
+            return Importer.MapImported(D, FoundTemplate);
+          }
 
-          Importer.MapImported(D->getTemplatedDecl(),
-                               FoundTemplate->getTemplatedDecl());
-          return Importer.MapImported(D, FoundTemplate);
+          continue;
         }
       }
 
@@ -4461,9 +4479,17 @@ Decl *ASTNodeImporter::VisitClassTemplateDecl(ClassTemplateDecl *D) {
 
   ToTemplated->setDescribedClassTemplate(D2);
 
+  if (ToTemplated->getPreviousDecl()) {
+    assert(
+        ToTemplated->getPreviousDecl()->getDescribedClassTemplate() &&
+        "Missing described template");
+    D2->setPreviousDecl(
+        ToTemplated->getPreviousDecl()->getDescribedClassTemplate());
+  }
   D2->setAccess(D->getAccess());
   D2->setLexicalDeclContext(LexicalDC);
-  LexicalDC->addDeclInternal(D2);
+  if (!IsFriend)
+    LexicalDC->addDeclInternal(D2);
 
   if (FromTemplated->isCompleteDefinition() &&
       !ToTemplated->isCompleteDefinition()) {