[MSVC] Improved lookup into dependent/non-dependent bases of dependent class

Patch improves lookup into dependendt bases of dependent class and adds lookup
into non-dependent bases.
Differential Revision: http://reviews.llvm.org/D7173


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@229817 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 135 insertions, 38 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index fd8b3e5431..e2547739f4 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -128,45 +128,85 @@ bool Sema::isSimpleTypeSpecifier(tok::TokenKind Kind) const {
   return false;
 }
 
+namespace {
+enum class UnqualifiedTypeNameLookupResult {
+  NotFound,
+  FoundNonType,
+  FoundType
+};
+} // namespace
+
+/// \brief Tries to perform unqualified lookup of the type decls in bases for
+/// dependent class.
+/// \return \a NotFound if no any decls is found, \a FoundNotType if found not a
+/// type decl, \a FoundType if only type decls are found.
+static UnqualifiedTypeNameLookupResult
+lookupUnqualifiedTypeNameInBase(Sema &S, const IdentifierInfo &II,
+                                SourceLocation NameLoc,
+                                const CXXRecordDecl *RD) {
+  if (!RD->hasDefinition())
+    return UnqualifiedTypeNameLookupResult::NotFound;
+  // Look for type decls in base classes.
+  UnqualifiedTypeNameLookupResult FoundTypeDecl =
+      UnqualifiedTypeNameLookupResult::NotFound;
+  for (const auto &Base : RD->bases()) {
+    const CXXRecordDecl *BaseRD = nullptr;
+    if (auto *BaseTT = Base.getType()->getAs<TagType>())
+      BaseRD = BaseTT->getAsCXXRecordDecl();
+    else if (auto *TST = Base.getType()->getAs<TemplateSpecializationType>()) {
+      // Look for type decls in dependent base classes that have known primary
+      // templates.
+      if (!TST || !TST->isDependentType())
+        continue;
+      auto *TD = TST->getTemplateName().getAsTemplateDecl();
+      if (!TD)
+        continue;
+      auto *BasePrimaryTemplate =
+          dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl());
+      if (!BasePrimaryTemplate)
+        continue;
+      BaseRD = BasePrimaryTemplate;
+    }
+    if (BaseRD) {
+      for (NamedDecl *ND : BaseRD->lookup(&II)) {
+        if (!isa<TypeDecl>(ND))
+          return UnqualifiedTypeNameLookupResult::FoundNonType;
+        FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
+      }
+      if (FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound) {
+        switch (lookupUnqualifiedTypeNameInBase(S, II, NameLoc, BaseRD)) {
+        case UnqualifiedTypeNameLookupResult::FoundNonType:
+          return UnqualifiedTypeNameLookupResult::FoundNonType;
+        case UnqualifiedTypeNameLookupResult::FoundType:
+          FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
+          break;
+        case UnqualifiedTypeNameLookupResult::NotFound:
+          break;
+        }
+      }
+    }
+  }
+
+  return FoundTypeDecl;
+}
+
 static ParsedType recoverFromTypeInKnownDependentBase(Sema &S,
                                                       const IdentifierInfo &II,
                                                       SourceLocation NameLoc) {
-  // Find the first parent class template context, if any.
-  // FIXME: Perform the lookup in all enclosing class templates.
+  // Lookup in the parent class template context, if any.
   const CXXRecordDecl *RD = nullptr;
-  for (DeclContext *DC = S.CurContext; DC; DC = DC->getParent()) {
+  UnqualifiedTypeNameLookupResult FoundTypeDecl =
+      UnqualifiedTypeNameLookupResult::NotFound;
+  for (DeclContext *DC = S.CurContext;
+       DC && FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound;
+       DC = DC->getParent()) {
+    // Look for type decls in dependent base classes that have known primary
+    // templates.
     RD = dyn_cast<CXXRecordDecl>(DC);
     if (RD && RD->getDescribedClassTemplate())
-      break;
-  }
-  if (!RD)
-    return ParsedType();
-
-  // Look for type decls in dependent base classes that have known primary
-  // templates.
-  bool FoundTypeDecl = false;
-  for (const auto &Base : RD->bases()) {
-    auto *TST = Base.getType()->getAs<TemplateSpecializationType>();
-    if (!TST || !TST->isDependentType())
-      continue;
-    auto *TD = TST->getTemplateName().getAsTemplateDecl();
-    if (!TD)
-      continue;
-    auto *BasePrimaryTemplate =
-        dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl());
-    if (!BasePrimaryTemplate)
-      continue;
-    // FIXME: Allow lookup into non-dependent bases of dependent bases, possibly
-    // by calling or integrating with the main LookupQualifiedName mechanism.
-    for (NamedDecl *ND : BasePrimaryTemplate->lookup(&II)) {
-      if (FoundTypeDecl)
-        return ParsedType();
-      FoundTypeDecl = isa<TypeDecl>(ND);
-      if (!FoundTypeDecl)
-        return ParsedType();
-    }
+      FoundTypeDecl = lookupUnqualifiedTypeNameInBase(S, II, NameLoc, RD);
   }
-  if (!FoundTypeDecl)
+  if (FoundTypeDecl != UnqualifiedTypeNameLookupResult::FoundType)
     return ParsedType();
 
   // We found some types in dependent base classes.  Recover as if the user
diff --git a/test/SemaTemplate/ms-lookup-template-base-classes.cpp b/test/SemaTemplate/ms-lookup-template-base-classes.cpp
index 979782f1cb..62451081c3 100644
--- a/test/SemaTemplate/ms-lookup-template-base-classes.cpp
+++ b/test/SemaTemplate/ms-lookup-template-base-classes.cpp
@@ -303,12 +303,12 @@ static_assert(sizeof(B<int>) == sizeof(A<int>::NameFromBase), "");
 }
 
 namespace two_types_in_base {
-template <typename T> struct A { typedef T NameFromBase; };
-template <typename T> struct B { struct NameFromBase { T m; }; };
+template <typename T> struct A { typedef T NameFromBase; }; // expected-note {{member found by ambiguous name lookup}}
+template <typename T> struct B { struct NameFromBase { T m; }; }; // expected-note {{member found by ambiguous name lookup}}
 template <typename T> struct C : A<T>, B<T> {
-  NameFromBase m; // expected-error {{unknown type name 'NameFromBase'}}
+  NameFromBase m; // expected-error {{member 'NameFromBase' found in multiple base classes of different types}} expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
 };
-static_assert(sizeof(C<int>) == 4, "");
+static_assert(sizeof(C<int>) == 4, ""); // expected-note {{in instantiation of template class 'two_types_in_base::C<int>' requested here}}
 }
 
 namespace type_and_decl_in_base {
@@ -386,9 +386,66 @@ namespace type_in_base_of_dependent_base {
 struct A { typedef int NameFromBase; };
 template <typename T>
 struct B : A {};
-// FIXME: MSVC accepts this.
 template <typename T>
-struct C : B<T> { NameFromBase m; }; // expected-error {{unknown type name 'NameFromBase'}}
+struct C : B<T> { NameFromBase m; }; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+}
+
+namespace type_in_second_dependent_base {
+template <typename T>
+struct A {};
+template<typename T>
+struct B { typedef T NameFromBase; };
+template <typename T>
+struct D : A<T>, B<T> { NameFromBase m; }; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+}
+
+namespace type_in_second_non_dependent_base {
+struct A {};
+struct B { typedef int NameFromBase; };
+template<typename T>
+struct C : A, B {};
+template <typename T>
+struct D : C<T> { NameFromBase m; }; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+}
+
+namespace type_in_virtual_base_of_dependent_base {
+template <typename T>
+struct A { typedef T NameFromBase; };
+template <typename T>
+struct B : virtual A<T> {};
+template <typename T>
+struct C : B<T>, virtual A<T> { NameFromBase m; }; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+C<int> c;
+}
+
+namespace type_in_base_of_multiple_dependent_bases {
+template <typename T>
+struct A { typedef T NameFromBase; };
+template <typename T>
+struct B : public A<T> {};
+template <typename T>
+struct C : B<T>, public A<T> { NameFromBase m; }; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}} expected-warning {{direct base 'A<int>' is inaccessible due to ambiguity:}}
+C<int> c; // expected-note {{in instantiation of template class 'type_in_base_of_multiple_dependent_bases::C<int>' requested here}}
+}
+
+namespace type_in_dependent_base_of_non_dependent_type {
+template<typename T> struct A { typedef int NameFromBase; };
+template<typename T> struct B : A<T> {
+  struct C;
+  template<typename TT>
+  struct D : C {
+    NameFromBase m; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+  };
+  struct E : C {
+    NameFromBase m; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+  };
+};
+template<typename T> struct B<T>::C : B {
+  NameFromBase m; // expected-warning {{use of identifier 'NameFromBase' found via unqualified lookup into dependent bases of class templates is a Microsoft extension}}
+};
+template<typename T> struct F : B<T>::C {
+  NameFromBase m; // expected-error {{unknown type name 'NameFromBase'}}
+};
 }
 
 namespace lookup_in_function_contexts {