Re: [PATCH] c++: implement __is_reference built-in trait

[Ken Matsui <kmatsui@cs.washington.edu>]

* cp-trait.def (names_builtin_p): Define __is_reference.

This changelog should be the following.

* cp-trait.def: Define __is_reference.

I am sorry for the confusion.

On Sat, Mar 18, 2023 at 9:07 PM Ken Matsui <kmatsui@cs.washington.edu> wrote:
>
> This patch implements built-in trait for std::is_reference.
>
> gcc/cp/ChangeLog:
>
> * cp-trait.def (names_builtin_p): Define __is_reference.
> * constraint.cc (diagnose_trait_expr): Handle CPTK_IS_REFERENCE.
> * semantics.cc (trait_expr_value): Likewise.
> (finish_trait_expr): Likewise.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/ext/has-builtin-1.C: Test existence of __is_reference.
> * g++.dg/ext/is_reference.C: New test.
>
> ---
> diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> index 273d15ab097..23e5bc24dbb 100644
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -3701,6 +3701,9 @@ diagnose_trait_expr (tree expr, tree args)
>      case CPTK_HAS_VIRTUAL_DESTRUCTOR:
>        inform (loc, "  %qT does not have a virtual destructor", t1);
>        break;
> +    case CPTK_IS_REFERENCE:
> +      inform (loc, "  %qT is not a reference", t1);
> +      break;
>      case CPTK_IS_ABSTRACT:
>        inform (loc, "  %qT is not an abstract class", t1);
>        break;
> diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> index bac593c0094..63a64152ce6 100644
> --- a/gcc/cp/cp-trait.def
> +++ b/gcc/cp/cp-trait.def
> @@ -67,6 +67,7 @@ DEFTRAIT_EXPR (IS_CONVERTIBLE, "__is_convertible", 2)
>  DEFTRAIT_EXPR (IS_EMPTY, "__is_empty", 1)
>  DEFTRAIT_EXPR (IS_ENUM, "__is_enum", 1)
>  DEFTRAIT_EXPR (IS_FINAL, "__is_final", 1)
> +DEFTRAIT_EXPR (IS_REFERENCE, "__is_reference", 1)
>  DEFTRAIT_EXPR (IS_LAYOUT_COMPATIBLE, "__is_layout_compatible", 2)
>  DEFTRAIT_EXPR (IS_LITERAL_TYPE, "__is_literal_type", 1)
>  DEFTRAIT_EXPR (IS_NOTHROW_ASSIGNABLE, "__is_nothrow_assignable", 2)
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 87c2e8a7111..dce98af4f72 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -11995,6 +11995,9 @@ trait_expr_value (cp_trait_kind kind, tree
> type1, tree type2)
>      case CPTK_IS_FINAL:
>        return CLASS_TYPE_P (type1) && CLASSTYPE_FINAL (type1);
>
> +    case CPTK_IS_REFERENCE:
> +      return type_code1 == REFERENCE_TYPE;
> +
>      case CPTK_IS_LAYOUT_COMPATIBLE:
>        return layout_compatible_type_p (type1, type2);
>
> @@ -12139,6 +12142,7 @@ finish_trait_expr (location_t loc,
> cp_trait_kind kind, tree type1, tree type2)
>      case CPTK_HAS_TRIVIAL_COPY:
>      case CPTK_HAS_TRIVIAL_DESTRUCTOR:
>      case CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS:
> +    case CPTK_IS_REFERENCE:
>        if (!check_trait_type (type1))
>   return error_mark_node;
>        break;
> diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> index f343e153e56..b697673790c 100644
> --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> @@ -146,3 +146,6 @@
>  #if !__has_builtin (__remove_cvref)
>  # error "__has_builtin (__remove_cvref) failed"
>  #endif
> +#if !__has_builtin (__is_reference)
> +# error "__has_builtin (__is_reference) failed"
> +#endif
> diff --git a/gcc/testsuite/g++.dg/ext/is_reference.C
> b/gcc/testsuite/g++.dg/ext/is_reference.C
> new file mode 100644
> index 00000000000..b4f048538e5
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/is_reference.C
> @@ -0,0 +1,26 @@
> +// { dg-do compile { target c++11 } }
> +
> +#define SA(X) static_assert((X),#X)
> +
> +SA(!__is_reference(void));
> +SA(!__is_reference(int*));
> +
> +SA(__is_reference(int&));
> +SA(__is_reference(const int&));
> +SA(__is_reference(volatile int&));
> +SA(__is_reference(const volatile int&));
> +
> +SA(__is_reference(int&&));
> +SA(__is_reference(const int&&));
> +SA(__is_reference(volatile int&&));
> +SA(__is_reference(const volatile int&&));
> +
> +SA(!__is_reference(int[3]));
> +SA(!__is_reference(const int[3]));
> +SA(!__is_reference(volatile int[3]));
> +SA(!__is_reference(const volatile int[3]));
> +
> +SA(!__is_reference(int(int)));
> +SA(!__is_reference(int(*const)(int)));
> +SA(!__is_reference(int(*volatile)(int)));
> +SA(!__is_reference(int(*const volatile)(int)));