Revert "Diagnose UnresolvedLookupExprs that resolve to instance members in static methods"

This reverts commit r250592.

It has issues around unevaluated contexts, like this:
  template <class T> struct A { T i; };
  template <class T>
  struct B : A<T> {
    using A<T>::i;
    typedef decltype(i) U;
  };
  template struct B<int>;

llvm-svn: 250774

2 files changed, 15 insertions, 22 deletions

diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
index 3256bd986ff..52dfceccb94 100644
--- a/clang/lib/Sema/SemaExprMember.cpp
+++ b/clang/lib/Sema/SemaExprMember.cpp
@@ -192,8 +192,10 @@ static IMAKind ClassifyImplicitMemberAccess(Sema &SemaRef,
 }
 
 /// Diagnose a reference to a field with no object available.
-void Sema::DiagnoseInstanceReference(const CXXScopeSpec &SS, NamedDecl *Rep,
-                                     const DeclarationNameInfo &nameInfo) {
+static void diagnoseInstanceReference(Sema &SemaRef,
+                                      const CXXScopeSpec &SS,
+                                      NamedDecl *Rep,
+                                      const DeclarationNameInfo &nameInfo) {
   SourceLocation Loc = nameInfo.getLoc();
   SourceRange Range(Loc);
   if (SS.isSet()) Range.setBegin(SS.getRange().getBegin());
@@ -201,7 +203,7 @@ void Sema::DiagnoseInstanceReference(const CXXScopeSpec &SS, NamedDecl *Rep,
   // Look through using shadow decls and aliases.
   Rep = Rep->getUnderlyingDecl();
 
-  DeclContext *FunctionLevelDC = getFunctionLevelDeclContext();
+  DeclContext *FunctionLevelDC = SemaRef.getFunctionLevelDeclContext();
   CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FunctionLevelDC);
   CXXRecordDecl *ContextClass = Method ? Method->getParent() : nullptr;
   CXXRecordDecl *RepClass = dyn_cast<CXXRecordDecl>(Rep->getDeclContext());
@@ -211,19 +213,20 @@ void Sema::DiagnoseInstanceReference(const CXXScopeSpec &SS, NamedDecl *Rep,
 
   if (IsField && InStaticMethod)
     // "invalid use of member 'x' in static member function"
-    Diag(Loc, diag::err_invalid_member_use_in_static_method)
+    SemaRef.Diag(Loc, diag::err_invalid_member_use_in_static_method)
         << Range << nameInfo.getName();
   else if (ContextClass && RepClass && SS.isEmpty() && !InStaticMethod &&
            !RepClass->Equals(ContextClass) && RepClass->Encloses(ContextClass))
     // Unqualified lookup in a non-static member function found a member of an
     // enclosing class.
-    Diag(Loc, diag::err_nested_non_static_member_use)
-        << IsField << RepClass << nameInfo.getName() << ContextClass << Range;
+    SemaRef.Diag(Loc, diag::err_nested_non_static_member_use)
+      << IsField << RepClass << nameInfo.getName() << ContextClass << Range;
   else if (IsField)
-    Diag(Loc, diag::err_invalid_non_static_member_use) << nameInfo.getName()
-                                                       << Range;
+    SemaRef.Diag(Loc, diag::err_invalid_non_static_member_use)
+      << nameInfo.getName() << Range;
   else
-    Diag(Loc, diag::err_member_call_without_object) << Range;
+    SemaRef.Diag(Loc, diag::err_member_call_without_object)
+      << Range;
 }
 
 /// Builds an expression which might be an implicit member expression.
@@ -257,7 +260,7 @@ Sema::BuildPossibleImplicitMemberExpr(const CXXScopeSpec &SS,
 
   case IMA_Error_StaticContext:
   case IMA_Error_Unrelated:
-    DiagnoseInstanceReference(SS, R.getRepresentativeDecl(),
+    diagnoseInstanceReference(*this, SS, R.getRepresentativeDecl(),
                               R.getLookupNameInfo());
     return ExprError();
   }
@@ -471,7 +474,7 @@ static void DiagnoseQualifiedMemberReference(Sema &SemaRef,
   // If this is an implicit member access, use a different set of
   // diagnostics.
   if (!BaseExpr)
-    return SemaRef.DiagnoseInstanceReference(SS, rep, nameInfo);
+    return diagnoseInstanceReference(SemaRef, SS, rep, nameInfo);
 
   SemaRef.Diag(nameInfo.getLoc(), diag::err_qualified_member_of_unrelated)
     << SS.getRange() << rep << BaseType;
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 81c56c2f2c6..31d69cbac35 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -9128,18 +9128,8 @@ TreeTransform<Derived>::TransformUnresolvedLookupExpr(
 
   // If we have neither explicit template arguments, nor the template keyword,
   // it's a normal declaration name.
-  if (!Old->hasExplicitTemplateArgs() && !TemplateKWLoc.isValid()) {
-    // If an UnresolvedLookupExpr resolved to an instance member, that's an
-    // error.
-    NamedDecl *D = R.getAsSingle<NamedDecl>();
-    if (D && D->isCXXInstanceMember()) {
-      SemaRef.DiagnoseInstanceReference(SS, D, Old->getNameInfo());
-      R.clear();
-      return ExprError();
-    }
-
+  if (!Old->hasExplicitTemplateArgs() && !TemplateKWLoc.isValid())
     return getDerived().RebuildDeclarationNameExpr(SS, R, Old->requiresADL());
-  }
 
   // If we have template arguments, rebuild them, then rebuild the
   // templateid expression.