Remove old concepts parsing code

[changyu]

Summary

This is so we can implement concepts per p0734r0. Relevant failing test cases are disabled.

include/clang/AST/DeclTemplate.h

class TemplateDecl : public NamedDecl {
   void anchor() override;
 
 protected:
   // Construct a template decl with the given name and parameters.
   // Used when there is no templated element (e.g., for tt-params).
   TemplateDecl(ConstrainedTemplateDeclInfo *CTDI, Kind DK, DeclContext *DC,
                SourceLocation L, DeclarationName Name,
                TemplateParameterList *Params)
-      : NamedDecl(DK, DC, L, Name), TemplatedDecl(nullptr, false),
+      : NamedDecl(DK, DC, L, Name), TemplatedDecl(nullptr),
         TemplateParams(CTDI) {
     this->setTemplateParameters(Params);
   }
 
   TemplateDecl(Kind DK, DeclContext *DC, SourceLocation L, DeclarationName Name,
                TemplateParameterList *Params)
       : TemplateDecl(nullptr, DK, DC, L, Name, Params) {}
 
   // Construct a template decl with name, parameters, and templated element.
   TemplateDecl(ConstrainedTemplateDeclInfo *CTDI, Kind DK, DeclContext *DC,
                SourceLocation L, DeclarationName Name,
                TemplateParameterList *Params, NamedDecl *Decl)
-      : NamedDecl(DK, DC, L, Name), TemplatedDecl(Decl, false),
+      : NamedDecl(DK, DC, L, Name), TemplatedDecl(Decl),
         TemplateParams(CTDI) {
     this->setTemplateParameters(Params);
   }
 
   TemplateDecl(Kind DK, DeclContext *DC, SourceLocation L, DeclarationName Name,
                TemplateParameterList *Params, NamedDecl *Decl)
       : TemplateDecl(nullptr, DK, DC, L, Name, Params, Decl) {}
 
public:
   Expr *getAssociatedConstraints() const {
     const TemplateDecl *const C = cast<TemplateDecl>(getCanonicalDecl());
     const auto *const CTDI =
         C->TemplateParams.dyn_cast<ConstrainedTemplateDeclInfo *>();
     return CTDI ? CTDI->getAssociatedConstraints() : nullptr;
   }
 
   /// Get the underlying, templated declaration.
-  NamedDecl *getTemplatedDecl() const { return TemplatedDecl.getPointer(); }
+  NamedDecl *getTemplatedDecl() const { return TemplatedDecl; }
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
 
   static bool classofKind(Kind K) {
     return K >= firstTemplate && K <= lastTemplate;
   }
 
   SourceRange getSourceRange() const override LLVM_READONLY {
     return SourceRange(getTemplateParameters()->getTemplateLoc(),
-                       TemplatedDecl.getPointer()->getSourceRange().getEnd());
+                       TemplatedDecl->getSourceRange().getEnd());
   }
 
-  /// Whether this is a (C++ Concepts TS) function or variable concept.
-  bool isConcept() const { return TemplatedDecl.getInt(); }
-  void setConcept() { TemplatedDecl.setInt(true); }
-
 protected:
-  /// \brief The named declaration from which this template was instantiated.
-  /// (or null).
-  ///
-  /// The boolean value will be true to indicate that this template
-  /// (function or variable) is a concept.
-  llvm::PointerIntPair<NamedDecl *, 1, bool> TemplatedDecl;
-
+  NamedDecl *TemplatedDecl;
   /// \brief The template parameter list and optional requires-clause
   /// associated with this declaration; alternatively, a
   /// \c ConstrainedTemplateDeclInfo if the associated constraints of the
   /// template are being tracked by this particular declaration.
   llvm::PointerUnion<TemplateParameterList *,
                      ConstrainedTemplateDeclInfo *>
       TemplateParams;
 
void setAssociatedConstraints(Expr *AC) {
     TemplateParams.get<ConstrainedTemplateDeclInfo *>()
         ->setAssociatedConstraints(AC);
   }
 
 public:
   /// \brief Initialize the underlying templated declaration and
   /// template parameters.
   void init(NamedDecl *templatedDecl, TemplateParameterList* templateParams) {
-    assert(!TemplatedDecl.getPointer() && "TemplatedDecl already set!");
+    assert(!TemplatedDecl && "TemplatedDecl already set!");
     assert(!TemplateParams && "TemplateParams already set!");
-    TemplatedDecl.setPointer(templatedDecl);
+    TemplatedDecl = templatedDecl;
     TemplateParams = templateParams;
   }
 };
 
 /// \brief Provides information about a function template specialization,
 /// which is a FunctionDecl that has been explicitly specialization or
 /// instantiated from a function template.
 class FunctionTemplateSpecializationInfo : public llvm::FoldingSetNode {
public:
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 
   /// \brief Load any lazily-loaded specializations from the external source.
   void LoadLazySpecializations() const;
 
   /// Get the underlying function declaration of the template.
   FunctionDecl *getTemplatedDecl() const {
-    return static_cast<FunctionDecl *>(TemplatedDecl.getPointer());
+    return static_cast<FunctionDecl *>(TemplatedDecl);
   }
 
   /// Returns whether this template declaration defines the primary
   /// pattern.
   bool isThisDeclarationADefinition() const {
     return getTemplatedDecl()->isThisDeclarationADefinition();
   }
 
public:
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 
   /// \brief Load any lazily-loaded specializations from the external source.
   void LoadLazySpecializations() const;
 
   /// \brief Get the underlying class declarations of the template.
   CXXRecordDecl *getTemplatedDecl() const {
-    return static_cast<CXXRecordDecl *>(TemplatedDecl.getPointer());
+    return static_cast<CXXRecordDecl *>(TemplatedDecl);
   }
 
   /// \brief Returns whether this template declaration defines the primary
   /// class pattern.
   bool isThisDeclarationADefinition() const {
     return getTemplatedDecl()->isThisDeclarationADefinition();
   }
 
protected:
   }
 
 public:
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 
   /// Get the underlying function declaration of the template.
   TypeAliasDecl *getTemplatedDecl() const {
-    return static_cast<TypeAliasDecl *>(TemplatedDecl.getPointer());
+    return static_cast<TypeAliasDecl *>(TemplatedDecl);
   }
 
 
   TypeAliasTemplateDecl *getCanonicalDecl() override {
     return cast<TypeAliasTemplateDecl>(
              RedeclarableTemplateDecl::getCanonicalDecl());
   }
   const TypeAliasTemplateDecl *getCanonicalDecl() const {
public:
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 
   /// \brief Load any lazily-loaded specializations from the external source.
   void LoadLazySpecializations() const;
 
   /// \brief Get the underlying variable declarations of the template.
   VarDecl *getTemplatedDecl() const {
-    return static_cast<VarDecl *>(TemplatedDecl.getPointer());
+    return static_cast<VarDecl *>(TemplatedDecl);
   }
 
   /// \brief Returns whether this template declaration defines the primary
   /// variable pattern.
   bool isThisDeclarationADefinition() const {
     return getTemplatedDecl()->isThisDeclarationADefinition();
   }
 

include/clang/Sema/DeclSpec.h

private:
   unsigned FS_noreturn_specified : 1;
 
   // friend-specifier
   unsigned Friend_specified : 1;
 
   // constexpr-specifier
   unsigned Constexpr_specified : 1;
 
-  // concept-specifier
-  unsigned Concept_specified : 1;
-
   union {
     UnionParsedType TypeRep;
     Decl *DeclRep;
     Expr *ExprRep;
   };
 
   // attributes.
   ParsedAttributes Attrs;
private:
   /// otherwise, it is the same as TSTLoc. Hence, the pair TSTLoc and
   /// TSTNameLoc provides source range info for tag types.
   SourceLocation TSTNameLoc;
   SourceRange TypeofParensRange;
   SourceLocation TQ_constLoc, TQ_restrictLoc, TQ_volatileLoc, TQ_atomicLoc,
       TQ_unalignedLoc;
   SourceLocation FS_inlineLoc, FS_virtualLoc, FS_explicitLoc, FS_noreturnLoc;
   SourceLocation FS_forceinlineLoc;
-  SourceLocation FriendLoc, ModulePrivateLoc, ConstexprLoc, ConceptLoc;
+  SourceLocation FriendLoc, ModulePrivateLoc, ConstexprLoc;
   SourceLocation TQ_pipeLoc;
 
   WrittenBuiltinSpecs writtenBS;
   void SaveWrittenBuiltinSpecs();
 
   ObjCDeclSpec *ObjCQualifiers;
 
   static bool isTypeRep(TST T) {
: StorageClassSpec(SCS_unspecified),
       TypeQualifiers(TQ_unspecified),
       FS_inline_specified(false),
       FS_forceinline_specified(false),
       FS_virtual_specified(false),
       FS_explicit_specified(false),
       FS_noreturn_specified(false),
       Friend_specified(false),
       Constexpr_specified(false),
-      Concept_specified(false),
       Attrs(attrFactory),
       writtenBS(),
       ObjCQualifiers(nullptr) {
   }
 
   // storage-class-specifier
   SCS getStorageClassSpec() const { return (SCS)StorageClassSpec; }
   TSCS getThreadStorageClassSpec() const {
bool setFunctionSpecNoreturn(SourceLocation Loc, const char *&PrevSpec,
                                unsigned &DiagID);
 
   bool SetFriendSpec(SourceLocation Loc, const char *&PrevSpec,
                      unsigned &DiagID);
   bool setModulePrivateSpec(SourceLocation Loc, const char *&PrevSpec,
                             unsigned &DiagID);
   bool SetConstexprSpec(SourceLocation Loc, const char *&PrevSpec,
                         unsigned &DiagID);
-  bool SetConceptSpec(SourceLocation Loc, const char *&PrevSpec,
-                      unsigned &DiagID);
 
   bool isFriendSpecified() const { return Friend_specified; }
   SourceLocation getFriendSpecLoc() const { return FriendLoc; }
 
   bool isModulePrivateSpecified() const { return ModulePrivateLoc.isValid(); }
   SourceLocation getModulePrivateSpecLoc() const { return ModulePrivateLoc; }
   
   bool isConstexprSpecified() const { return Constexpr_specified; }
   SourceLocation getConstexprSpecLoc() const { return ConstexprLoc; }
 
-  bool isConceptSpecified() const { return Concept_specified; }
-  SourceLocation getConceptSpecLoc() const { return ConceptLoc; }
-
   void ClearConstexprSpec() {
     Constexpr_specified = false;
     ConstexprLoc = SourceLocation();
   }
 
-  void ClearConceptSpec() {
-    Concept_specified = false;
-    ConceptLoc = SourceLocation();
-  }
-
   AttributePool &getAttributePool() const {
     return Attrs.getPool();
   }
 
   /// \brief Concatenates two attribute lists.
   ///
   /// The GCC attribute syntax allows for the following:
   ///

lib/Parse/ParseDecl.cpp

case tok::kw___module_private__:
       isInvalid = DS.setModulePrivateSpec(Loc, PrevSpec, DiagID);
       break;
 
     // constexpr
     case tok::kw_constexpr:
       isInvalid = DS.SetConstexprSpec(Loc, PrevSpec, DiagID);
       break;
 
-    // concept
-    case tok::kw_concept:
-      isInvalid = DS.SetConceptSpec(Loc, PrevSpec, DiagID);
-      break;
-
     // type-specifier
     case tok::kw_short:
       isInvalid = DS.SetTypeSpecWidth(DeclSpec::TSW_short, Loc, PrevSpec,
                                       DiagID, Policy);
       break;
     case tok::kw_long:
       if (DS.getTypeSpecWidth() != DeclSpec::TSW_long)
         isInvalid = DS.SetTypeSpecWidth(DeclSpec::TSW_long, Loc, PrevSpec,
case tok::kw_typeof:
 
     // GNU attributes.
   case tok::kw___attribute:
 
     // C++11 decltype and constexpr.
   case tok::annot_decltype:
   case tok::kw_constexpr:
 
-    // C++ Concepts TS - concept
-  case tok::kw_concept:
-
     // C11 _Atomic
   case tok::kw__Atomic:
     return true;
 
     // GNU ObjC bizarre protocol extension: <proto1,proto2> with implicit 'id'.
   case tok::less:
     return getLangOpts().ObjC1;
 

lib/Parse/ParseTentative.cpp

case tok::kw_decltype:
 
     // decl-specifier:
     //   storage-class-specifier
     //   type-specifier
     //   function-specifier
     //   'friend'
     //   'typedef'
     //   'constexpr'
-    //   'concept'
   case tok::kw_friend:
   case tok::kw_typedef:
   case tok::kw_constexpr:
-  case tok::kw_concept:
     // storage-class-specifier
   case tok::kw_register:
   case tok::kw_static:
   case tok::kw_extern:
   case tok::kw_mutable:
   case tok::kw_auto:
   case tok::kw___thread:
   case tok::kw_thread_local:

lib/Sema/DeclSpec.cpp

if (Constexpr_specified) {
     PrevSpec = "constexpr";
     return true;
   }
   Constexpr_specified = true;
   ConstexprLoc = Loc;
   return false;
 }
 
-bool DeclSpec::SetConceptSpec(SourceLocation Loc, const char *&PrevSpec,
-                              unsigned &DiagID) {
-  if (Concept_specified) {
-    DiagID = diag::ext_duplicate_declspec;
-    PrevSpec = "concept";
-    return true;
-  }
-  Concept_specified = true;
-  ConceptLoc = Loc;
-  return false;
-}
-
 void DeclSpec::SaveWrittenBuiltinSpecs() {
   writtenBS.Sign = getTypeSpecSign();
   writtenBS.Width = getTypeSpecWidth();
   writtenBS.Type = getTypeSpecType();
   // Search the list of attributes for the presence of a mode attribute.
   writtenBS.ModeAttr = false;
   AttributeList* attrs = getAttributes().getList();
   while (attrs) {

lib/Sema/SemaDecl.cpp

if (Tag)
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
           << GetDiagnosticTypeSpecifierID(DS.getTypeSpecType());
     else
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_no_declarators);
     // Don't emit warnings after this error.
     return TagD;
   }
 
-  if (DS.isConceptSpecified()) {
-    // C++ Concepts TS [dcl.spec.concept]p1: A concept definition refers to
-    // either a function concept and its definition or a variable concept and
-    // its initializer.
-    Diag(DS.getConceptSpecLoc(), diag::err_concept_wrong_decl_kind);
-    return TagD;
-  }
-
   DiagnoseFunctionSpecifiers(DS);
 
   if (DS.isFriendSpecified()) {
     // If we're dealing with a decl but not a TagDecl, assume that
     // whatever routines created it handled the friendship aspect.
     if (TagD && !Tag)
       return nullptr;
     return ActOnFriendTypeDecl(S, DS, TemplateParams);
if (Previous.isSingleTagDecl() &&
       (TemplateParamLists.size() == 0 || R->isFunctionType()))
     Previous.clear();
 
   // Check that there are no default arguments other than in the parameters
   // of a function declaration (C++ only).
   if (getLangOpts().CPlusPlus)
     CheckExtraCXXDefaultArguments(D);
 
-  if (D.getDeclSpec().isConceptSpecified()) {
-    // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
-    // applied only to the definition of a function template or variable
-    // template, declared in namespace scope
-    if (!TemplateParamLists.size()) {
-      Diag(D.getDeclSpec().getConceptSpecLoc(),
-           diag:: err_concept_wrong_decl_kind);
-      return nullptr;
-    }
-
-    if (!DC->getRedeclContext()->isFileContext()) {
-      Diag(D.getIdentifierLoc(),
-           diag::err_concept_decls_may_only_appear_in_namespace_scope);
-      return nullptr;
-    }
-  }
-
   NamedDecl *New;
 
   bool AddToScope = true;
   if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef) {
     if (TemplateParamLists.size()) {
       Diag(D.getIdentifierLoc(), diag::err_template_typedef);
       return nullptr;
     }
Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
   DiagnoseFunctionSpecifiers(D.getDeclSpec());
 
   if (D.getDeclSpec().isInlineSpecified())
     Diag(D.getDeclSpec().getInlineSpecLoc(), diag::err_inline_non_function)
         << getLangOpts().CPlusPlus17;
   if (D.getDeclSpec().isConstexprSpecified())
     Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_invalid_constexpr)
       << 1;
-  if (D.getDeclSpec().isConceptSpecified())
-    Diag(D.getDeclSpec().getConceptSpecLoc(),
-         diag::err_concept_wrong_decl_kind);
 
   if (D.getName().Kind != UnqualifiedId::IK_Identifier) {
     if (D.getName().Kind == UnqualifiedId::IK_DeductionGuideName)
       Diag(D.getName().StartLocation,
            diag::err_deduction_guide_invalid_specifier)
           << "typedef";
     else
       Diag(D.getName().StartLocation, diag::err_typedef_not_identifier)
if (!getLangOpts().CPlusPlus) {
     if (D.getDeclSpec().isConstexprSpecified()) {
       NewVD->setConstexpr(true);
       // C++1z [dcl.spec.constexpr]p1:
       //   A static data member declared with the constexpr specifier is
       //   implicitly an inline variable.
       if (NewVD->isStaticDataMember() && getLangOpts().CPlusPlus17)
         NewVD->setImplicitlyInline();
     }
-
-    if (D.getDeclSpec().isConceptSpecified()) {
-      if (VarTemplateDecl *VTD = NewVD->getDescribedVarTemplate())
-        VTD->setConcept();
-
-      // C++ Concepts TS [dcl.spec.concept]p2: A concept definition shall not
-      // be declared with the thread_local, inline, friend, or constexpr
-      // specifiers, [...]
-      if (D.getDeclSpec().getThreadStorageClassSpec() == TSCS_thread_local) {
-        Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
-             diag::err_concept_decl_invalid_specifiers)
-            << 0 << 0;
-        NewVD->setInvalidDecl(true);
-      }
-
-      if (D.getDeclSpec().isConstexprSpecified()) {
-        Diag(D.getDeclSpec().getConstexprSpecLoc(),
-             diag::err_concept_decl_invalid_specifiers)
-            << 0 << 3;
-        NewVD->setInvalidDecl(true);
-      }
-
-      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
-      // applied only to the definition of a function template or variable
-      // template, declared in namespace scope.
-      if (IsVariableTemplateSpecialization) {
-        Diag(D.getDeclSpec().getConceptSpecLoc(),
-             diag::err_concept_specified_specialization)
-            << (IsPartialSpecialization ? 2 : 1);
-      }
-
-      // C++ Concepts TS [dcl.spec.concept]p6: A variable concept has the
-      // following restrictions:
-      // - The declared type shall have the type bool.
-      if (!Context.hasSameType(NewVD->getType(), Context.BoolTy) &&
-          !NewVD->isInvalidDecl()) {
-        Diag(D.getIdentifierLoc(), diag::err_variable_concept_bool_decl);
-        NewVD->setInvalidDecl(true);
-      }
-    }
   }
 
   if (D.getDeclSpec().isInlineSpecified()) {
     if (!getLangOpts().CPlusPlus) {
       Diag(D.getDeclSpec().getInlineSpecLoc(), diag::err_inline_non_function)
           << 0;
     } else if (CurContext->isFunctionOrMethod()) {
       // 'inline' is not allowed on block scope variable declaration.
if (!Previous.empty()) {
         << Name << computeDeclContext(D.getCXXScopeSpec(), true)
         << D.getCXXScopeSpec().getRange();
       NewVD->setInvalidDecl();
     }
 
     if (!IsVariableTemplateSpecialization)
       D.setRedeclaration(CheckVariableDeclaration(NewVD, Previous));
 
-    // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare [...]
-    // an explicit specialization (14.8.3) or a partial specialization of a
-    // concept definition.
-    if (IsVariableTemplateSpecialization &&
-        !D.getDeclSpec().isConceptSpecified() && !Previous.empty() &&
-        Previous.isSingleResult()) {
-      NamedDecl *PreviousDecl = Previous.getFoundDecl();
-      if (VarTemplateDecl *VarTmpl = dyn_cast<VarTemplateDecl>(PreviousDecl)) {
-        if (VarTmpl->isConcept()) {
-          Diag(NewVD->getLocation(), diag::err_concept_specialized)
-              << 1                            /*variable*/
-              << (IsPartialSpecialization ? 2 /*partially specialized*/
-                                          : 1 /*explicitly specialized*/);
-          Diag(VarTmpl->getLocation(), diag::note_previous_declaration);
-          NewVD->setInvalidDecl();
-        }
-      }
-    }
-
     if (NewTemplate) {
       VarTemplateDecl *PrevVarTemplate =
           NewVD->getPreviousDecl()
               ? NewVD->getPreviousDecl()->getDescribedVarTemplate()
               : nullptr;
 
       // Check the template parameter list of this declaration, possibly
       // merging in the template parameter list from the previous variable
Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
   if (IsLocalExternDecl)
     NewFD->setLocalExternDecl();
 
   if (getLangOpts().CPlusPlus) {
     bool isInline = D.getDeclSpec().isInlineSpecified();
     bool isVirtual = D.getDeclSpec().isVirtualSpecified();
     bool isExplicit = D.getDeclSpec().isExplicitSpecified();
     bool isConstexpr = D.getDeclSpec().isConstexprSpecified();
-    bool isConcept = D.getDeclSpec().isConceptSpecified();
     isFriend = D.getDeclSpec().isFriendSpecified();
     if (isFriend && !isInline && D.isFunctionDefinition()) {
       // C++ [class.friend]p5
       //   A function can be defined in a friend declaration of a
       //   class . . . . Such a function is implicitly inline.
       NewFD->setImplicitlyInline();
     }
 
if (isConstexpr) {
 
       // C++11 [dcl.constexpr]p3: functions declared constexpr are required to
       // be either constructors or to return a literal type. Therefore,
       // destructors cannot be declared constexpr.
       if (isa<CXXDestructorDecl>(NewFD))
         Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_constexpr_dtor);
     }
 
-    if (isConcept) {
-      // This is a function concept.
-      if (FunctionTemplateDecl *FTD = NewFD->getDescribedFunctionTemplate())
-        FTD->setConcept();
-
-      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
-      // applied only to the definition of a function template [...]
-      if (!D.isFunctionDefinition()) {
-        Diag(D.getDeclSpec().getConceptSpecLoc(),
-             diag::err_function_concept_not_defined);
-        NewFD->setInvalidDecl();
-      }
-
-      // C++ Concepts TS [dcl.spec.concept]p1: [...] A function concept shall
-      // have no exception-specification and is treated as if it were specified
-      // with noexcept(true) (15.4). [...]
-      if (const FunctionProtoType *FPT = R->getAs<FunctionProtoType>()) {
-        if (FPT->hasExceptionSpec()) {
-          SourceRange Range;
-          if (D.isFunctionDeclarator())
-            Range = D.getFunctionTypeInfo().getExceptionSpecRange();
-          Diag(NewFD->getLocation(), diag::err_function_concept_exception_spec)
-              << FixItHint::CreateRemoval(Range);
-          NewFD->setInvalidDecl();
-        } else {
-          Context.adjustExceptionSpec(NewFD, EST_BasicNoexcept);
-        }
-
-        // C++ Concepts TS [dcl.spec.concept]p5: A function concept has the
-        // following restrictions:
-        // - The declared return type shall have the type bool.
-        if (!Context.hasSameType(FPT->getReturnType(), Context.BoolTy)) {
-          Diag(D.getIdentifierLoc(), diag::err_function_concept_bool_ret);
-          NewFD->setInvalidDecl();
-        }
-
-        // C++ Concepts TS [dcl.spec.concept]p5: A function concept has the
-        // following restrictions:
-        // - The declaration's parameter list shall be equivalent to an empty
-        //   parameter list.
-        if (FPT->getNumParams() > 0 || FPT->isVariadic())
-          Diag(NewFD->getLocation(), diag::err_function_concept_with_params);
-      }
-
-      // C++ Concepts TS [dcl.spec.concept]p2: Every concept definition is
-      // implicity defined to be a constexpr declaration (implicitly inline)
-      NewFD->setImplicitlyInline();
-
-      // C++ Concepts TS [dcl.spec.concept]p2: A concept definition shall not
-      // be declared with the thread_local, inline, friend, or constexpr
-      // specifiers, [...]
-      if (isInline) {
-        Diag(D.getDeclSpec().getInlineSpecLoc(),
-             diag::err_concept_decl_invalid_specifiers)
-            << 1 << 1;
-        NewFD->setInvalidDecl(true);
-      }
-
-      if (isFriend) {
-        Diag(D.getDeclSpec().getFriendSpecLoc(),
-             diag::err_concept_decl_invalid_specifiers)
-            << 1 << 2;
-        NewFD->setInvalidDecl(true);
-      }
-
-      if (isConstexpr) {
-        Diag(D.getDeclSpec().getConstexprSpecLoc(),
-             diag::err_concept_decl_invalid_specifiers)
-            << 1 << 3;
-        NewFD->setInvalidDecl(true);
-      }
-
-      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
-      // applied only to the definition of a function template or variable
-      // template, declared in namespace scope.
-      if (isFunctionTemplateSpecialization) {
-        Diag(D.getDeclSpec().getConceptSpecLoc(),
-             diag::err_concept_specified_specialization) << 1;
-        NewFD->setInvalidDecl(true);
-        return NewFD;
-      }
-    }
-
     // If __module_private__ was specified, mark the function accordingly.
     if (D.getDeclSpec().isModulePrivateSpecified()) {
       if (isFunctionTemplateSpecialization) {
         SourceLocation ModulePrivateLoc
           = D.getDeclSpec().getModulePrivateSpecLoc();
         Diag(ModulePrivateLoc, diag::err_module_private_specialization)
           << 0
           << FixItHint::CreateRemoval(ModulePrivateLoc);
if (Var->isConstexpr() && !Var->isThisDeclarationADefinition() &&
         }
       } else {
         Diag(Var->getLocation(), diag::err_invalid_constexpr_var_decl);
         Var->setInvalidDecl();
         return;
       }
     }
 
-    // C++ Concepts TS [dcl.spec.concept]p1: [...]  A variable template
-    // definition having the concept specifier is called a variable concept. A
-    // concept definition refers to [...] a variable concept and its initializer.
-    if (VarTemplateDecl *VTD = Var->getDescribedVarTemplate()) {
-      if (VTD->isConcept()) {
-        Diag(Var->getLocation(), diag::err_var_concept_not_initialized);
-        Var->setInvalidDecl();
-        return;
-      }
-    }
-
     // OpenCL v1.1 s6.5.3: variables declared in the constant address space must
     // be initialized.
     if (!Var->isInvalidDecl() &&
         Var->getType().getAddressSpace() == LangAS::opencl_constant &&
         Var->getStorageClass() != SC_Extern && !Var->getInit()) {
       Diag(Var->getLocation(), diag::err_opencl_constant_no_init);
       Var->setInvalidDecl();
       return;
if (DeclSpec::TSCS TSCS = DS.getThreadStorageClassSpec())
     Diag(DS.getThreadStorageClassSpecLoc(), diag::err_invalid_thread)
       << DeclSpec::getSpecifierName(TSCS);
   if (DS.isInlineSpecified())
     Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
         << getLangOpts().CPlusPlus17;
   if (DS.isConstexprSpecified())
     Diag(DS.getConstexprSpecLoc(), diag::err_invalid_constexpr)
       << 0;
-  if (DS.isConceptSpecified())
-    Diag(DS.getConceptSpecLoc(), diag::err_concept_wrong_decl_kind);
 
   DiagnoseFunctionSpecifiers(DS);
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
   QualType parmDeclType = TInfo->getType();
 
   if (getLangOpts().CPlusPlus) {
     // Check that there are no default arguments inside the type of this

lib/Sema/SemaDeclCXX.cpp

Diag(D.getIdentifierLoc(), diag::err_deduction_guide_wrong_scope)
       << GuidedTemplateDecl;
     Diag(GuidedTemplateDecl->getLocation(), diag::note_template_decl_here);
   }
 
   auto &DS = D.getMutableDeclSpec();
   // We leave 'friend' and 'virtual' to be rejected in the normal way.
   if (DS.hasTypeSpecifier() || DS.getTypeQualifiers() ||
       DS.getStorageClassSpecLoc().isValid() || DS.isInlineSpecified() ||
-      DS.isNoreturnSpecified() || DS.isConstexprSpecified() ||
-      DS.isConceptSpecified()) {
+      DS.isNoreturnSpecified() || DS.isConstexprSpecified()) {
     BadSpecifierDiagnoser Diagnoser(
         *this, D.getIdentifierLoc(),
         diag::err_deduction_guide_invalid_specifier);
 
     Diagnoser.check(DS.getStorageClassSpecLoc(), DS.getStorageClassSpec());
     DS.ClearStorageClassSpecs();
     SC = SC_None;
 
     // 'explicit' is permitted.
     Diagnoser.check(DS.getInlineSpecLoc(), "inline");
     Diagnoser.check(DS.getNoreturnSpecLoc(), "_Noreturn");
     Diagnoser.check(DS.getConstexprSpecLoc(), "constexpr");
-    Diagnoser.check(DS.getConceptSpecLoc(), "concept");
     DS.ClearConstexprSpec();
-    DS.ClearConceptSpec();
 
     Diagnoser.check(DS.getConstSpecLoc(), "const");
     Diagnoser.check(DS.getRestrictSpecLoc(), "__restrict");
     Diagnoser.check(DS.getVolatileSpecLoc(), "volatile");
     Diagnoser.check(DS.getAtomicSpecLoc(), "_Atomic");
     Diagnoser.check(DS.getUnalignedSpecLoc(), "__unaligned");
     DS.ClearTypeQualifiers();
 

lib/Sema/SemaTemplate.cpp

UnresolvedSetIterator Result = getMostSpecialized(
       PDiag(diag::note_function_template_spec_matched));
 
   if (Result == Candidates.end())
     return true;
 
   // Ignore access information;  it doesn't figure into redeclaration checking.
   FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
 
-  // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare [...]
-  // an explicit specialization (14.8.3) [...] of a concept definition.
-  if (Specialization->getPrimaryTemplate()->isConcept()) {
-    Diag(FD->getLocation(), diag::err_concept_specialized)
-        << 0 /*function*/ << 1 /*explicitly specialized*/;
-    Diag(Specialization->getLocation(), diag::note_previous_declaration);
-    return true;
-  }
-
   FunctionTemplateSpecializationInfo *SpecInfo
     = Specialization->getTemplateSpecializationInfo();
   assert(SpecInfo && "Function template specialization info missing?");
 
   // Note: do not overwrite location info if previous template
   // specialization kind was explicit.
   TemplateSpecializationKind TSK = SpecInfo->getTemplateSpecializationKind();
   if (TSK == TSK_Undeclared || TSK == TSK_ImplicitInstantiation) {
Diag(D.getDeclSpec().getInlineSpecLoc(),
            diag::warn_explicit_instantiation_inline_0x)
       << FixItHint::CreateRemoval(D.getDeclSpec().getInlineSpecLoc());
   if (D.getDeclSpec().isConstexprSpecified() && R->isFunctionType())
     // FIXME: Add a fix-it to remove the 'constexpr' and add a 'const' if one is
     // not already specified.
     Diag(D.getDeclSpec().getConstexprSpecLoc(),
          diag::err_explicit_instantiation_constexpr);
 
-  // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
-  // applied only to the definition of a function template or variable template,
-  // declared in namespace scope.
-  if (D.getDeclSpec().isConceptSpecified()) {
-    Diag(D.getDeclSpec().getConceptSpecLoc(),
-         diag::err_concept_specified_specialization) << 0;
-    return true;
-  }
-
   // A deduction guide is not on the list of entities that can be explicitly
   // instantiated.
   if (Name.getNameKind() == DeclarationName::CXXDeductionGuideName) {
     Diag(D.getDeclSpec().getLocStart(), diag::err_deduction_guide_specialized)
       << /*explicit instantiation*/ 0;
     return true;
   }
 
if (!PrevTemplate) {
         Diag(D.getIdentifierLoc(),
              diag::err_explicit_instantiation_without_template_id)
           << PrevTemplate;
         Diag(PrevTemplate->getLocation(),
              diag::note_explicit_instantiation_here);
         return true;
       }
 
-      // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare an
-      // explicit instantiation (14.8.2) [...] of a concept definition.
-      if (PrevTemplate->isConcept()) {
-        Diag(D.getIdentifierLoc(), diag::err_concept_specialized)
-            << 1 /*variable*/ << 0 /*explicitly instantiated*/;
-        Diag(PrevTemplate->getLocation(), diag::note_previous_declaration);
-        return true;
-      }
-
       // Translate the parser's template argument list into our AST format.
       TemplateArgumentListInfo TemplateArgs =
           makeTemplateArgumentListInfo(*this, *D.getName().TemplateId);
 
       DeclResult Res = CheckVarTemplateId(PrevTemplate, TemplateLoc,
                                           D.getIdentifierLoc(), TemplateArgs);
       if (Res.isInvalid())
         return true;
DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
   FunctionTemplateDecl *FunTmpl = Specialization->getPrimaryTemplate();
   if (D.getName().getKind() != UnqualifiedId::IK_TemplateId && !FunTmpl &&
       D.getCXXScopeSpec().isSet() &&
       !ScopeSpecifierHasTemplateId(D.getCXXScopeSpec()))
     Diag(D.getIdentifierLoc(),
          diag::ext_explicit_instantiation_without_qualified_id)
     << Specialization << D.getCXXScopeSpec().getRange();
 
-  // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare an
-  // explicit instantiation (14.8.2) [...] of a concept definition.
-  if (FunTmpl && FunTmpl->isConcept() &&
-      !D.getDeclSpec().isConceptSpecified()) {
-    Diag(D.getIdentifierLoc(), diag::err_concept_specialized)
-        << 0 /*function*/ << 0 /*explicitly instantiated*/;
-    Diag(FunTmpl->getLocation(), diag::note_previous_declaration);
-    return true;
-  }
-
   CheckExplicitInstantiationScope(*this,
                    FunTmpl? (NamedDecl *)FunTmpl
                           : Specialization->getInstantiatedFromMemberFunction(),
                                   D.getIdentifierLoc(),
                                   D.getCXXScopeSpec().isSet());
 
   // FIXME: Create some kind of ExplicitInstantiationDecl here.
   return (Decl*) nullptr;

test/CXX/concepts-ts/dcl.dcl/lit.cfg.py

+# -*- Python -*-
+
+import os
+import lit.formats
+
+from lit.llvm import llvm_config
+
+# Configuration file for the 'lit' test runner.
+
+# name: The name of this test suite.
+config.name = 'Clang-Concepts-TS-Unsupported'
+
+# testFormat: The test format to use to interpret tests.
+#
+# For now we require '&&' between commands, until they get globally killed and
+# the test runner updated.
+config.test_format = lit.formats.ShTest(not llvm_config.use_lit_shell)
+
+# suffixes: A list of file extensions to treat as test files.
+config.suffixes = ['.c', '.cpp', '.cppm', '.m', '.mm', '.cu',
+                   '.ll', '.cl', '.s', '.S', '.modulemap', '.test', '.rs']
+
+config.unsupported = True
+
+# test_source_root: The root path where tests are located.
+config.test_source_root = os.path.dirname(__file__)

test/Parser/cxx-concept-declaration.cpp

 
-// Support parsing of function concepts and variable concepts
+// Support parsing of concepts
+// Disabled for now.
+// expected-no-diagnostics
 
 // RUN:  %clang_cc1 -std=c++14 -fconcepts-ts -x c++ -verify %s
-
-template<typename T> concept bool C1 = true;
-
-template<typename T> concept bool C2() { return true; }
-
-template<typename T>
-struct A { typedef bool Boolean; };
-
-template<int N>
-A<void>::Boolean concept C3(!0);
-
-template<typename T, int = 0>
-concept auto C4(void) -> bool { return true; }
-
-constexpr int One = 1;
-
-template <typename>
-static concept decltype(!0) C5 { bool(One) };
-
-template<typename T> concept concept bool C6 = true; // expected-warning {{duplicate 'concept' declaration specifier}}
-
-template<typename T> concept concept bool C7() { return true; } // expected-warning {{duplicate 'concept' declaration specifier}}
-
-template<concept T> concept bool D1 = true; // expected-error {{unknown type name 'T'}}
+// template<typename T> concept C1 = true;