[c++2a] [concepts] Add rudimentary parsing support for template concept declarations

This patch is a tweak of changyu's patch: https://reviews.llvm.org/D40381. It differs in that the recognition of the 'concept' token is moved into the machinery that recognizes declaration-specifiers - this allows us to leverage the attribute handling machinery more seamlessly.

See the test file to get a sense of the basic parsing that this patch supports. 

There is much more work to be done before concepts are usable...

Thanks Changyu!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@330794 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 40 insertions, 0 deletions

diff --git a/include/clang/AST/DeclTemplate.h b/include/clang/AST/DeclTemplate.h
index 9c68352e76..1fe95f4a59 100644
--- a/include/clang/AST/DeclTemplate.h
+++ b/include/clang/AST/DeclTemplate.h
@@ -3015,6 +3015,46 @@ public:
   static bool classofKind(Kind K) { return K == VarTemplate; }
 };
 
+/// \brief Represents a C++2a ([temp] p1) concept-definition.
+class ConceptDecl : public TemplateDecl {
+protected:
+  Expr *ConstraintExpr;
+
+  ConceptDecl(DeclContext *DC,
+              SourceLocation NameLoc, DeclarationName Name,
+              TemplateParameterList *Params,
+              Expr *ConstraintExpr)
+      : TemplateDecl(nullptr, Concept, DC, NameLoc, Name, Params),
+        ConstraintExpr(ConstraintExpr) {};
+public:
+  static ConceptDecl *Create(ASTContext &C, DeclContext *DC,
+                             SourceLocation NameLoc, DeclarationName Name,
+                             TemplateParameterList *Params,
+                             Expr *ConstraintExpr);
+  static ConceptDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+
+  Expr *getConstraintExpr() const {
+    return ConstraintExpr;
+  }
+
+  void setConstraintExpr(Expr *CE) {
+    ConstraintExpr = CE;
+  }
+
+  SourceRange getSourceRange() const override LLVM_READONLY {
+    return SourceRange(getTemplateParameters()->getTemplateLoc(),
+                       getConstraintExpr()->getLocEnd());
+  }
+
+  // Implement isa/cast/dyncast/etc.
+  static bool classof(const Decl *D) { return classofKind(D->getKind()); }
+  static bool classofKind(Kind K) { return K == Concept; }
+
+  friend class ASTReader;
+  friend class ASTDeclReader;
+  friend class ASTDeclWriter;
+};
+
 inline NamedDecl *getAsNamedDecl(TemplateParameter P) {
   if (auto *PD = P.dyn_cast<TemplateTypeParmDecl *>())
     return PD;