Fix implementation of [temp.local]p4.

When a template-name is looked up, we need to give injected-class-name
declarations of class templates special treatment, as they denote a
template rather than a type.

Previously we achieved this by applying a filter to the lookup results
after completing name lookup, but that is incorrect in various ways, not
least of which is that it lost all information about access and how
members were named, and the filtering caused us to generally lose
all ambiguity errors between templates and non-templates.

We now preserve the lookup results exactly, and the few places that need
to map from a declaration found by name lookup into a declaration of a
template do so explicitly. Deduplication of repeated lookup results of
the same injected-class-name declaration is done by name lookup instead
of after the fact.

This reinstates r354091, which was previously reverted in r354097
because it exposed bugs in lldb and compiler-rt. Those bugs were fixed
in r354173 and r354174 respectively.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@354176 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 2 deletions

diff --git a/include/clang/Sema/Lookup.h b/include/clang/Sema/Lookup.h
index 990005f1cc..0466d06d75 100644
--- a/include/clang/Sema/Lookup.h
+++ b/include/clang/Sema/Lookup.h
@@ -172,7 +172,8 @@ public:
       : SemaPtr(Other.SemaPtr), NameInfo(Other.NameInfo),
         LookupKind(Other.LookupKind), IDNS(Other.IDNS), Redecl(Other.Redecl),
         ExternalRedecl(Other.ExternalRedecl), HideTags(Other.HideTags),
-        AllowHidden(Other.AllowHidden) {}
+        AllowHidden(Other.AllowHidden),
+        TemplateNameLookup(Other.TemplateNameLookup) {}
 
   // FIXME: Remove these deleted methods once the default build includes
   // -Wdeprecated.
@@ -193,7 +194,8 @@ public:
         HideTags(std::move(Other.HideTags)),
         Diagnose(std::move(Other.Diagnose)),
         AllowHidden(std::move(Other.AllowHidden)),
-        Shadowed(std::move(Other.Shadowed)) {
+        Shadowed(std::move(Other.Shadowed)),
+        TemplateNameLookup(std::move(Other.TemplateNameLookup)) {
     Other.Paths = nullptr;
     Other.Diagnose = false;
   }
@@ -216,6 +218,7 @@ public:
     Diagnose = std::move(Other.Diagnose);
     AllowHidden = std::move(Other.AllowHidden);
     Shadowed = std::move(Other.Shadowed);
+    TemplateNameLookup = std::move(Other.TemplateNameLookup);
     Other.Paths = nullptr;
     Other.Diagnose = false;
     return *this;
@@ -286,6 +289,15 @@ public:
     HideTags = Hide;
   }
 
+  /// Sets whether this is a template-name lookup. For template-name lookups,
+  /// injected-class-names are treated as naming a template rather than a
+  /// template specialization.
+  void setTemplateNameLookup(bool TemplateName) {
+    TemplateNameLookup = TemplateName;
+  }
+
+  bool isTemplateNameLookup() const { return TemplateNameLookup; }
+
   bool isAmbiguous() const {
     return getResultKind() == Ambiguous;
   }
@@ -739,6 +751,9 @@ private:
   /// declaration that we skipped. This only happens when \c LookupKind
   /// is \c LookupRedeclarationWithLinkage.
   bool Shadowed = false;
+
+  /// True if we're looking up a template-name.
+  bool TemplateNameLookup = false;
 };
 
 /// Consumes visible declarations found when searching for