When qualified lookup into the current instantiation fails (because it

finds nothing), and the current instantiation has dependent base
classes, treat the qualified lookup as if it referred to an unknown
specialization. Fixes PR6031.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@93433 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 02581c1241a4c4790959436ebc564569d60322f6..336a895de8cfb0737f3a0bb418d85b5e1b2bb2d3 100644 (file)
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -393,6 +393,9 @@ public:
     return reverse_base_class_const_iterator(vbases_begin());
  }
 
+  /// \brief Determine whether this class has any dependent base classes.
+  bool hasAnyDependentBases() const;
+
   /// Iterator access to method members.  The method iterator visits
   /// all method members of the class, including non-instance methods,
   /// special methods, etc.

diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index b30d335918ab1e2bc5db94cd178f34bdc39544fd..1cce35c0b39a4c8baf3f19d8850c4b9d4316846a 100644 (file)
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -144,6 +144,19 @@ CXXRecordDecl::setBases(ASTContext &C,
   }
 }
 
+/// Callback function for CXXRecordDecl::forallBases that acknowledges
+/// that it saw a base class.
+static bool SawBase(const CXXRecordDecl *, void *) {
+  return true;
+}
+
+bool CXXRecordDecl::hasAnyDependentBases() const {
+  if (!isDependentContext())
+    return false;
+
+  return !forallBases(SawBase, 0);
+}
+
 bool CXXRecordDecl::hasConstCopyConstructor(ASTContext &Context) const {
   return getCopyConstructor(Context, Qualifiers::Const) != 0;
 }

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 8fc34880c1103bef20b054847206e594e0da9665..44bf48915ea7d7e66780583e3d101e6b46e460bd 100644 (file)
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -2032,6 +2032,7 @@ public:
   bool isDependentScopeSpecifier(const CXXScopeSpec &SS);
   CXXRecordDecl *getCurrentInstantiationOf(NestedNameSpecifier *NNS);
   bool isUnknownSpecialization(const CXXScopeSpec &SS);
+  bool isCurrentInstantiationWithDependentBases(const CXXScopeSpec &SS);
 
   /// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
   /// global scope ('::').

diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index a8f118ebdd67271c409b12292f3db179dbcd0047..8594583ec3eff223cbbec9f3b301305a149d1a2e 100644 (file)
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -210,6 +210,28 @@ bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
   return getCurrentInstantiationOf(NNS) == 0;
 }
 
+/// \brief Determine whether the given scope specifier refers to a
+/// current instantiation that has any dependent base clases.
+///
+/// This check is typically used when we've performed lookup into the
+/// current instantiation of a template, but that lookup failed. When
+/// there are dependent bases present, however, the lookup needs to be
+/// delayed until template instantiation time.
+bool Sema::isCurrentInstantiationWithDependentBases(const CXXScopeSpec &SS) {
+  if (!SS.isSet())
+    return false;
+
+  NestedNameSpecifier *NNS = (NestedNameSpecifier*)SS.getScopeRep();
+  if (!NNS->isDependent())
+    return false;
+
+  CXXRecordDecl *CurrentInstantiation = getCurrentInstantiationOf(NNS);
+  if (!CurrentInstantiation)
+    return false;
+
+  return CurrentInstantiation->hasAnyDependentBases();
+}
+
 /// \brief If the given nested name specifier refers to the current
 /// instantiation, return the declaration that corresponds to that
 /// current instantiation (C++0x [temp.dep.type]p1).

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 75fe7fd00fcf10afe2459ca21142f563b782dabf..c54745f552e10b5ed1ea60e6de3880ada41a4e2d 100644 (file)
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -4785,8 +4785,18 @@ Sema::DeclPtrTy Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
     if (Previous.isAmbiguous())
       return DeclPtrTy();
 
-    // A tag 'foo::bar' must already exist.
     if (Previous.empty()) {
+      // Name lookup did not find anything. However, if the
+      // nested-name-specifier refers to the current instantiation,
+      // and that current instantiation has any dependent base
+      // classes, we might find something at instantiation time: treat
+      // this as a dependent elaborated-type-specifier.
+      if (isCurrentInstantiationWithDependentBases(SS)) {
+        IsDependent = true;
+        return DeclPtrTy();
+      }
+
+      // A tag 'foo::bar' must already exist.
       Diag(NameLoc, diag::err_not_tag_in_scope) << Name << SS.getRange();
       Name = 0;
       Invalid = true;

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index e75277e823e0ae156cbb05011eeb311fa407a81f..d2e70cf9ad6f0efd64ff1ab0c271318ecff58738 100644 (file)
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -1608,15 +1608,19 @@ Sema::ActOnDependentTemplateName(SourceLocation TemplateKWLoc,
     TemplateTy Template;
     TemplateNameKind TNK = isTemplateName(0, SS, Name, ObjectType,
                                           EnteringContext, Template);
-    if (TNK == TNK_Non_template) {
+    if (TNK == TNK_Non_template && 
+        isCurrentInstantiationWithDependentBases(SS)) {
+      // This is a dependent template.
+    } else if (TNK == TNK_Non_template) {
       Diag(Name.getSourceRange().getBegin(), 
            diag::err_template_kw_refers_to_non_template)
         << GetNameFromUnqualifiedId(Name)
         << Name.getSourceRange();
       return TemplateTy();
+    } else {
+      // We found something; return it.
+      return Template;
     }
-
-    return Template;
   }
 
   NestedNameSpecifier *Qualifier
@@ -4765,6 +4769,14 @@ Sema::CheckTypenameType(NestedNameSpecifier *NNS, const IdentifierInfo &II,
   Decl *Referenced = 0;
   switch (Result.getResultKind()) {
   case LookupResult::NotFound:
+    if (CurrentInstantiation && CurrentInstantiation->hasAnyDependentBases()) {
+      // We performed a lookup in the current instantiation and didn't
+      // find anything. However, this current instantiation has
+      // dependent bases, so we might be able to find something at
+      // instantiation time: just build a TypenameType and move on.
+      return Context.getTypenameType(NNS, &II);
+    }
+
     DiagID = diag::err_typename_nested_not_found;
     break;
 

diff --git a/test/SemaTemplate/dependent-base-classes.cpp b/test/SemaTemplate/dependent-base-classes.cpp
index 242765894f7341236f544fcd96f6a8f58a9b6ed7..b9666dba61c661251299c7a47834ef4415badd95 100644 (file)
--- a/test/SemaTemplate/dependent-base-classes.cpp
+++ b/test/SemaTemplate/dependent-base-classes.cpp
@@ -10,3 +10,56 @@ struct X1 : T::apply<U> { }; // expected-error{{missing 'template' keyword prior
 
 template<typename T>
 struct X2 : vector<T> { }; // expected-error{{unknown template name 'vector'}}
+
+namespace PR6031 {
+  template<typename T>
+  struct A;
+
+  template <class X>
+  struct C { };
+
+  template <class TT>
+  struct II {
+    typedef typename A<TT>::type type;
+  };
+
+  template <class TT>
+  struct FI : II<TT>
+  {
+    C<typename FI::type> a;
+  };
+
+  template <class TT>
+  struct FI2
+  {
+    C<typename FI2::type> a; // expected-error{{no type named 'type' in 'struct PR6031::FI2'}} \
+        // expected-error{{C++ requires a type specifier for all declarations}}
+  };
+
+  template<typename T>
+  struct Base {
+    class Nested { };
+    template<typename U> struct MemberTemplate { };
+    int a;
+  };
+
+  template<typename T>
+  struct HasDepBase : Base<T> {
+    int foo() {
+      class HasDepBase::Nested nested;
+      typedef typename HasDepBase::template MemberTemplate<T>::type type;
+      return HasDepBase::a;
+    }
+  };
+
+  template<typename T>
+  struct NoDepBase {
+    int foo() {
+      class NoDepBase::Nested nested; // expected-error{{'Nested' does not name a tag member in the specified scope}}
+      typedef typename NoDepBase::template MemberTemplate<T>::type type; // expected-error{{'MemberTemplate' following the 'template' keyword does not refer to a template}} \
+      // FIXME: expected-error{{expected an identifier or template-id after '::'}} \
+      // FIXME: expected-error{{unqualified-id}}
+      return NoDepBase::a; // expected-error{{no member named 'a' in 'struct PR6031::NoDepBase'}}
+    }
+  };
+}