[PATCH 1/8] c++: Implement __is_const built-in trait

[Ken Matsui]

On Sat, Dec 23, 2023 at 1:36 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
>
> This patch implements built-in trait for std::is_const.
>
> gcc/cp/ChangeLog:
>
>         * cp-trait.def: Define __is_const.
>         * constraint.cc (diagnose_trait_expr): Handle CPTK_IS_CONST.
>         * semantics.cc (trait_expr_value): Likewise.
>         (finish_trait_expr): Likewise.
>
> gcc/testsuite/ChangeLog:
>
>         * g++.dg/ext/has-builtin-1.C: Test existence of __is_const.
>         * g++.dg/ext/is_const.C: New test.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>  gcc/cp/constraint.cc                     |  3 +++
>  gcc/cp/cp-trait.def                      |  1 +
>  gcc/cp/semantics.cc                      |  4 ++++
>  gcc/testsuite/g++.dg/ext/has-builtin-1.C |  3 +++
>  gcc/testsuite/g++.dg/ext/is_const.C      | 19 +++++++++++++++++++
>  5 files changed, 30 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_const.C
>
> diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> index eeacead52a5..f1b07aa2853 100644
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -3734,6 +3734,9 @@ diagnose_trait_expr (tree expr, tree args)
>      case CPTK_IS_CLASS:
>        inform (loc, "  %qT is not a class", t1);
>        break;
> +    case CPTK_IS_CONST:
> +      inform (loc, "  %qT is not a const type", t1);
> +      break;
>      case CPTK_IS_CONSTRUCTIBLE:
>        if (!t2)
>      inform (loc, "  %qT is not default constructible", t1);
> diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> index 394f006f20f..36faed9c0b3 100644
> --- a/gcc/cp/cp-trait.def
> +++ b/gcc/cp/cp-trait.def
> @@ -64,6 +64,7 @@ DEFTRAIT_EXPR (IS_ASSIGNABLE, "__is_assignable", 2)
>  DEFTRAIT_EXPR (IS_BASE_OF, "__is_base_of", 2)
>  DEFTRAIT_EXPR (IS_BOUNDED_ARRAY, "__is_bounded_array", 1)
>  DEFTRAIT_EXPR (IS_CLASS, "__is_class", 1)
> +DEFTRAIT_EXPR (IS_CONST, "__is_const", 1)
>  DEFTRAIT_EXPR (IS_CONSTRUCTIBLE, "__is_constructible", -1)
>  DEFTRAIT_EXPR (IS_CONVERTIBLE, "__is_convertible", 2)
>  DEFTRAIT_EXPR (IS_EMPTY, "__is_empty", 1)
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index e6dba29ee81..364d87ee34d 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -12415,6 +12415,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
>      case CPTK_IS_CLASS:
>        return NON_UNION_CLASS_TYPE_P (type1);
>
> +    case CPTK_IS_CONST:
> +      return CP_TYPE_CONST_P (type1);
> +
>      case CPTK_IS_CONSTRUCTIBLE:
>        return is_xible (INIT_EXPR, type1, type2);
>
> @@ -12657,6 +12660,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
>      case CPTK_IS_ARRAY:
>      case CPTK_IS_BOUNDED_ARRAY:
>      case CPTK_IS_CLASS:
> +    case CPTK_IS_CONST:
>      case CPTK_IS_ENUM:
>      case CPTK_IS_FUNCTION:
>      case CPTK_IS_MEMBER_FUNCTION_POINTER:
> diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> index 02b4b4d745d..e3640faeb96 100644
> --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> @@ -71,6 +71,9 @@
>  #if !__has_builtin (__is_class)
>  # error "__has_builtin (__is_class) failed"
>  #endif
> +#if !__has_builtin (__is_const)
> +# error "__has_builtin (__is_const) failed"
> +#endif
>  #if !__has_builtin (__is_constructible)
>  # error "__has_builtin (__is_constructible) failed"
>  #endif
> diff --git a/gcc/testsuite/g++.dg/ext/is_const.C b/gcc/testsuite/g++.dg/ext/is_const.C
> new file mode 100644
> index 00000000000..8f2d7c2fce9
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/is_const.C
> @@ -0,0 +1,19 @@
> +// { dg-do compile { target c++11 } }
> +
> +#include <testsuite_tr1.h>
> +

Please ignore this patch series.  I should have removed testsuite_tr1.h.

> +using namespace __gnu_test;
> +
> +#define SA(X) static_assert((X),#X)
> +
> +// Positive tests.
> +SA(__is_const(const int));
> +SA(__is_const(const volatile int));
> +SA(__is_const(cClassType));
> +SA(__is_const(cvClassType));
> +
> +// Negative tests.
> +SA(!__is_const(int));
> +SA(!__is_const(volatile int));
> +SA(!__is_const(ClassType));
> +SA(!__is_const(vClassType));
> --
> 2.43.0
>