[PATCH] D11600: Add concept to VarDecl and diagnostic for unitialized variable concept

[Aaron Ballman]

On Wed, Jul 29, 2015 at 1:39 PM, Nathan Wilson <nwilson20 at gmail.com> wrote:
> nwilson created this revision.
> nwilson added reviewers: rsmith, fraggamuffin, hubert.reinterpretcast, faisalv, aaron.ballman.
> nwilson added a subscriber: cfe-commits.
> Herald added a subscriber: aemerson.
>
> Add IsConcept bit to VarDecl::NonParmVarDeclBitfields and associated isConcept/setConcept member functions. Set IsConcept to true when 'concept' specifier is in variable declaration. Create diagnostic when variable concept is not initialized.

LGTM!

~Aaron

>
> http://reviews.llvm.org/D11600
>
> Files:
>   include/clang/AST/Decl.h
>   include/clang/Basic/DiagnosticSemaKinds.td
>   lib/Sema/SemaDecl.cpp
>   test/SemaCXX/cxx-concept-declaration.cpp
>
> Index: test/SemaCXX/cxx-concept-declaration.cpp
> ===================================================================
> --- test/SemaCXX/cxx-concept-declaration.cpp
> +++ test/SemaCXX/cxx-concept-declaration.cpp
> @@ -15,3 +15,6 @@
>  struct C {
>    template<typename T> static concept bool D3 = true; // expected-error {{concept declarations may only appear in namespace scope}}
>  };
> +
> +template<typename T>
> +concept bool D6; // expected-error {{variable concept declaration must be initialized}}
> Index: lib/Sema/SemaDecl.cpp
> ===================================================================
> --- lib/Sema/SemaDecl.cpp
> +++ lib/Sema/SemaDecl.cpp
> @@ -5849,6 +5849,9 @@
>
>      if (D.getDeclSpec().isConstexprSpecified())
>        NewVD->setConstexpr(true);
> +
> +    if (D.getDeclSpec().isConceptSpecified())
> +      NewVD->setConcept(true);
>    }
>
>    // Set the lexical context. If the declarator has a C++ scope specifier, the
> @@ -9407,6 +9410,16 @@
>        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 (Var->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() &&
> Index: include/clang/Basic/DiagnosticSemaKinds.td
> ===================================================================
> --- include/clang/Basic/DiagnosticSemaKinds.td
> +++ include/clang/Basic/DiagnosticSemaKinds.td
> @@ -1970,6 +1970,8 @@
>    "concept declarations may only appear in namespace scope">;
>  def err_function_concept_not_defined : Error<
>    "function concept declaration must be a definition">;
> +def err_var_concept_not_initialized : Error<
> +  "variable concept declaration must be initialized">;
>
>  // C++11 char16_t/char32_t
>  def warn_cxx98_compat_unicode_type : Warning<
> Index: include/clang/AST/Decl.h
> ===================================================================
> --- include/clang/AST/Decl.h
> +++ include/clang/AST/Decl.h
> @@ -815,6 +815,9 @@
>      /// \brief Whether this variable is (C++0x) constexpr.
>      unsigned IsConstexpr : 1;
>
> +    /// \brief Whether this variable is (C++ Concepts TS) concept.
> +    unsigned IsConcept : 1;
> +
>      /// \brief Whether this variable is the implicit variable for a lambda
>      /// init-capture.
>      unsigned IsInitCapture : 1;
> @@ -1238,6 +1241,15 @@
>      NonParmVarDeclBits.IsConstexpr = IC;
>    }
>
> +  /// Whether this variable is (C++ Concepts TS) concept.
> +  bool isConcept() const {
> +    return isa<ParmVarDecl>(this) ? false : NonParmVarDeclBits.IsConcept;
> +  }
> +  void setConcept(bool IC) {
> +    assert(!isa<ParmVarDecl>(this));
> +    NonParmVarDeclBits.IsConcept = IC;
> +  }
> +
>    /// Whether this variable is the implicit variable for a lambda init-capture.
>    bool isInitCapture() const {
>      return isa<ParmVarDecl>(this) ? false : NonParmVarDeclBits.IsInitCapture;
>
>