PR43080: Do not build context-sensitive expressions during name classification.

Summary:
We don't know what context to use until the classification result is
consumed by the parser, which could happen in a different semantic
context. So don't build the expression that results from name
classification until we get to that point and can handle it properly.

This covers everything except C++ implicit class member access, which
is a little awkward to handle properly in the face of the protected
member access check. But it at least fixes all the currently-filed
instances of PR43080.

Reviewers: efriedma

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68896

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374826 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 100 insertions, 19 deletions

diff --git a/include/clang/Basic/TokenKinds.def b/include/clang/Basic/TokenKinds.def
index 0a8d27ec2e..94fe1ba63a 100644
--- a/include/clang/Basic/TokenKinds.def
+++ b/include/clang/Basic/TokenKinds.def
@@ -728,6 +728,11 @@ ANNOTATION(typename)     // annotation for a C typedef name, a C++ (possibly
 ANNOTATION(template_id)  // annotation for a C++ template-id that names a
                          // function template specialization (not a type),
                          // e.g., "std::swap<int>"
+ANNOTATION(non_type)     // annotation for a single non-type declaration
+ANNOTATION(non_type_undeclared) // annotation for an undeclared identifier that
+                                // was assumed to be an ADL-only function name
+ANNOTATION(non_type_dependent)  // annotation for an assumed non-type member of
+                                // a dependent base class
 ANNOTATION(primary_expr) // annotation for a primary expression
 ANNOTATION(decltype)     // annotation for a decltype expression,
                          // e.g., "decltype(foo.bar())"
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index 920921f693..52d159062c 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -766,6 +766,22 @@ private:
     Tok.setAnnotationValue(T.getAsOpaquePtr());
   }
 
+  static NamedDecl *getNonTypeAnnotation(const Token &Tok) {
+    return static_cast<NamedDecl*>(Tok.getAnnotationValue());
+  }
+
+  static void setNonTypeAnnotation(Token &Tok, NamedDecl *ND) {
+    Tok.setAnnotationValue(ND);
+  }
+
+  static IdentifierInfo *getIdentifierAnnotation(const Token &Tok) {
+    return static_cast<IdentifierInfo*>(Tok.getAnnotationValue());
+  }
+
+  static void setIdentifierAnnotation(Token &Tok, IdentifierInfo *ND) {
+    Tok.setAnnotationValue(ND);
+  }
+
   /// Read an already-translated primary expression out of an annotation
   /// token.
   static ExprResult getExprAnnotation(const Token &Tok) {
@@ -799,8 +815,7 @@ private:
     /// Annotation was successful.
     ANK_Success
   };
-  AnnotatedNameKind TryAnnotateName(bool IsAddressOfOperand,
-                                    CorrectionCandidateCallback *CCC = nullptr);
+  AnnotatedNameKind TryAnnotateName(CorrectionCandidateCallback *CCC = nullptr);
 
   /// Push a tok::annot_cxxscope token onto the token stream.
   void AnnotateScopeToken(CXXScopeSpec &SS, bool IsNewAnnotation);
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index b8b59fdf93..0403df4ba7 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -1855,29 +1855,52 @@ public:
   /// Describes the result of the name lookup and resolution performed
   /// by \c ClassifyName().
   enum NameClassificationKind {
+    /// This name is not a type or template in this context, but might be
+    /// something else.
     NC_Unknown,
+    /// Classification failed; an error has been produced.
     NC_Error,
+    /// The name has been typo-corrected to a keyword.
     NC_Keyword,
+    /// The name was classified as a type.
     NC_Type,
-    NC_Expression,
-    NC_NestedNameSpecifier,
+    /// The name was classified as a specific non-type, non-template
+    /// declaration. ActOnNameClassifiedAsNonType should be called to
+    /// convert the declaration to an expression.
+    NC_NonType,
+    /// The name was classified as an ADL-only function name.
+    /// ActOnNameClassifiedAsUndeclaredNonType should be called to convert the
+    /// result to an expression.
+    NC_UndeclaredNonType,
+    /// The name denotes a member of a dependent type that could not be
+    /// resolved. ActOnNameClassifiedAsDependentNonType should be called to
+    /// convert the result to an expression.
+    NC_DependentNonType,
+    /// The name was classified as a non-type, and an expression representing
+    /// that name has been formed.
+    NC_ContextIndependentExpr,
+    /// The name was classified as a template whose specializations are types.
     NC_TypeTemplate,
+    /// The name was classified as a variable template name.
     NC_VarTemplate,
+    /// The name was classified as a function template name.
     NC_FunctionTemplate,
+    /// The name was classified as an ADL-only function template name.
     NC_UndeclaredTemplate,
   };
 
   class NameClassification {
     NameClassificationKind Kind;
-    ExprResult Expr;
-    TemplateName Template;
-    ParsedType Type;
+    union {
+      ExprResult Expr;
+      NamedDecl *NonTypeDecl;
+      TemplateName Template;
+      ParsedType Type;
+    };
 
     explicit NameClassification(NameClassificationKind Kind) : Kind(Kind) {}
 
   public:
-    NameClassification(ExprResult Expr) : Kind(NC_Expression), Expr(Expr) {}
-
     NameClassification(ParsedType Type) : Kind(NC_Type), Type(Type) {}
 
     NameClassification(const IdentifierInfo *Keyword) : Kind(NC_Keyword) {}
@@ -1890,8 +1913,24 @@ public:
       return NameClassification(NC_Unknown);
     }
 
-    static NameClassification NestedNameSpecifier() {
-      return NameClassification(NC_NestedNameSpecifier);
+    static NameClassification ContextIndependentExpr(ExprResult E) {
+      NameClassification Result(NC_ContextIndependentExpr);
+      Result.Expr = E;
+      return Result;
+    }
+
+    static NameClassification NonType(NamedDecl *D) {
+      NameClassification Result(NC_NonType);
+      Result.NonTypeDecl = D;
+      return Result;
+    }
+
+    static NameClassification UndeclaredNonType() {
+      return NameClassification(NC_UndeclaredNonType);
+    }
+
+    static NameClassification DependentNonType() {
+      return NameClassification(NC_DependentNonType);
     }
 
     static NameClassification TypeTemplate(TemplateName Name) {
@@ -1920,14 +1959,19 @@ public:
 
     NameClassificationKind getKind() const { return Kind; }
 
+    ExprResult getExpression() const {
+      assert(Kind == NC_ContextIndependentExpr);
+      return Expr;
+    }
+
     ParsedType getType() const {
       assert(Kind == NC_Type);
       return Type;
     }
 
-    ExprResult getExpression() const {
-      assert(Kind == NC_Expression);
-      return Expr;
+    NamedDecl *getNonTypeDecl() const {
+      assert(Kind == NC_NonType);
+      return NonTypeDecl;
     }
 
     TemplateName getTemplateName() const {
@@ -1971,17 +2015,29 @@ public:
   /// \param NextToken The token following the identifier. Used to help
   /// disambiguate the name.
   ///
-  /// \param IsAddressOfOperand True if this name is the operand of a unary
-  ///        address of ('&') expression, assuming it is classified as an
-  ///        expression.
-  ///
   /// \param CCC The correction callback, if typo correction is desired.
   NameClassification ClassifyName(Scope *S, CXXScopeSpec &SS,
                                   IdentifierInfo *&Name, SourceLocation NameLoc,
                                   const Token &NextToken,
-                                  bool IsAddressOfOperand,
                                   CorrectionCandidateCallback *CCC = nullptr);
 
+  /// Act on the result of classifying a name as an undeclared (ADL-only)
+  /// non-type declaration.
+  ExprResult ActOnNameClassifiedAsUndeclaredNonType(IdentifierInfo *Name,
+                                                    SourceLocation NameLoc);
+  /// Act on the result of classifying a name as an undeclared member of a
+  /// dependent base class.
+  ExprResult ActOnNameClassifiedAsDependentNonType(const CXXScopeSpec &SS,
+                                                   IdentifierInfo *Name,
+                                                   SourceLocation NameLoc,
+                                                   bool IsAddressOfOperand);
+  /// Act on the result of classifying a name as a specific non-type
+  /// declaration.
+  ExprResult ActOnNameClassifiedAsNonType(Scope *S, const CXXScopeSpec &SS,
+                                          NamedDecl *Found,
+                                          SourceLocation NameLoc,
+                                          const Token &NextToken);
+
   /// Describes the detailed kind of a template name. Used in diagnostics.
   enum class TemplateNameKindForDiagnostics {
     ClassTemplate,
@@ -3407,6 +3463,7 @@ public:
                               LookupNameKind NameKind,
                               RedeclarationKind Redecl
                                 = NotForRedeclaration);
+  bool LookupBuiltin(LookupResult &R);
   bool LookupName(LookupResult &R, Scope *S,
                   bool AllowBuiltinCreation = false);
   bool LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
@@ -4389,6 +4446,10 @@ public:
                       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr,
                       ArrayRef<Expr *> Args = None, TypoExpr **Out = nullptr);
 
+  DeclResult LookupIvarInObjCMethod(LookupResult &Lookup, Scope *S,
+                                    IdentifierInfo *II);
+  ExprResult BuildIvarRefExpr(Scope *S, SourceLocation Loc, ObjCIvarDecl *IV);
+
   ExprResult LookupInObjCMethod(LookupResult &LookUp, Scope *S,
                                 IdentifierInfo *II,
                                 bool AllowBuiltinCreation=false);