[Concepts] Implement a portion of Concepts TS[dcl.spec.concept]p5 and p6:

Diagnose if the return type of a function concept or declaration type of a
variable concept is not bool.

Reviewers: hubert.reinterpretcast

Differential Revision: http://reviews.llvm.org/D16163

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@259159 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticSemaKinds.td

@@ -2074,6 +2074,10 @@ def err_concept_decl_invalid_specifiers : Error<
   "'%select{thread_local|inline|friend|constexpr}1'">;
 def err_function_concept_with_params : Error<
   "function concept cannot have any parameters">;
+def err_function_concept_bool_ret : Error<
+  "declared return type of function concept must be 'bool'">;
+def err_variable_concept_bool_decl : Error<
+  "declared type of variable concept must be 'bool'">;
 
 // C++11 char16_t/char32_t
 def warn_cxx98_compat_unicode_type : Warning<

lib/Sema/SemaDecl.cpp

@@ -6001,6 +6001,15 @@ Sema::ActOnVariableDeclarator(Scope *S, Declarator &D, DeclContext *DC,
             << 0 << 3;
         NewVD->setInvalidDecl(true);
       }
+
+      // 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);
+      }
     }
   }
@@ -7681,6 +7690,14 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
           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

test/CXX/concepts-ts/dcl.dcl/dcl.spec/dcl.spec.concept/p5.cpp

@@ -11,3 +11,15 @@ concept bool fcpp(Ts... ts) { return true; } // expected-error {{function concep
 
 template<typename T>
 concept bool fcpva(...) { return true; } // expected-error {{function concept cannot have any parameters}}
+
+template<typename T>
+concept const bool fcrtc() { return true; } // expected-error {{declared return type of function concept must be 'bool'}}
+
+template<typename T>
+concept int fcrti() { return 5; } // expected-error {{declared return type of function concept must be 'bool'}}
+
+template<typename T>
+concept float fcrtf() { return 5.5; } // expected-error {{declared return type of function concept must be 'bool'}}
+
+template<typename T>
+concept decltype(auto) fcrtd(void) { return true; } // expected-error {{declared return type of function concept must be 'bool'}}

test/CXX/concepts-ts/dcl.dcl/dcl.spec/dcl.spec.concept/p6.cpp

+// RUN:  %clang_cc1 -std=c++14 -fconcepts-ts -x c++ -verify %s
+
+template<typename T>
+concept bool vc { true };
+
+template<typename T>
+struct B { typedef bool Boolean; };
+
+template<int N>
+B<void>::Boolean concept vctb(!0);
+
+template<typename T>
+concept const bool vctc { true }; // expected-error {{declared type of variable concept must be 'bool'}}
+
+template<typename T>
+concept int vcti { 5 }; // expected-error {{declared type of variable concept must be 'bool'}}
+
+template<typename T>
+concept float vctf { 5.5 }; // expected-error {{declared type of variable concept must be 'bool'}}
+
+template<typename T>
+concept auto vcta { true }; // expected-error {{declared type of variable concept must be 'bool'}}
+
+template<typename T>
+concept decltype(auto) vctd { true }; // expected-error {{declared type of variable concept must be 'bool'}}