[PATCH v7 3/6] c++: implement __is_function built-in trait

[Patrick Palka]

On Mon, 12 Jun 2023, Ken Matsui via Gcc-patches wrote:

> This patch implements built-in trait for std::is_function.
> 
> gcc/cp/ChangeLog:
> 
> 	* cp-trait.def: Define __is_function.
> 	* constraint.cc (diagnose_trait_expr): Handle CPTK_IS_FUNCTION.
> 	* semantics.cc (trait_expr_value): Likewise.
> 	(finish_trait_expr): Likewise.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/ext/has-builtin-1.C: Test existence of __is_function.
> 	* g++.dg/ext/is_function.C: New test.

LGTM

> 
> Signed-off-by: Ken Matsui <kmatsui@cs.washington.edu>
> ---
>  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_function.C   | 58 ++++++++++++++++++++++++
>  5 files changed, 69 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/ext/is_function.C
> 
> diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> index f6951ee2670..927605c6cb7 100644
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -3754,6 +3754,9 @@ diagnose_trait_expr (tree expr, tree args)
>      case CPTK_IS_UNION:
>        inform (loc, "  %qT is not a union", t1);
>        break;
> +    case CPTK_IS_FUNCTION:
> +      inform (loc, "  %qT is not a function", t1);
> +      break;
>      case CPTK_IS_AGGREGATE:
>        inform (loc, "  %qT is not an aggregate", t1);
>        break;
> diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> index 1e3310cd682..3cd3babc242 100644
> --- a/gcc/cp/cp-trait.def
> +++ b/gcc/cp/cp-trait.def
> @@ -83,6 +83,7 @@ DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE, "__is_trivially_assignable", 2)
>  DEFTRAIT_EXPR (IS_TRIVIALLY_CONSTRUCTIBLE, "__is_trivially_constructible", -1)
>  DEFTRAIT_EXPR (IS_TRIVIALLY_COPYABLE, "__is_trivially_copyable", 1)
>  DEFTRAIT_EXPR (IS_UNION, "__is_union", 1)
> +DEFTRAIT_EXPR (IS_FUNCTION, "__is_function", 1)
>  DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY, "__reference_constructs_from_temporary", 2)
>  DEFTRAIT_EXPR (REF_CONVERTS_FROM_TEMPORARY, "__reference_converts_from_temporary", 2)
>  /* FIXME Added space to avoid direct usage in GCC 13.  */
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 2f37bc353a1..b976633645a 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -12072,6 +12072,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
>      case CPTK_IS_ENUM:
>        return type_code1 == ENUMERAL_TYPE;
>  
> +    case CPTK_IS_FUNCTION:
> +      return type_code1 == FUNCTION_TYPE;
> +
>      case CPTK_IS_FINAL:
>        return CLASS_TYPE_P (type1) && CLASSTYPE_FINAL (type1);
>  
> @@ -12293,6 +12296,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
>      case CPTK_IS_UNION:
>      case CPTK_IS_SAME:
>      case CPTK_IS_REFERENCE:
> +    case CPTK_IS_FUNCTION:
>        break;
>  
>      case CPTK_IS_LAYOUT_COMPATIBLE:
> diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> index b697673790c..90eb00ebf2d 100644
> --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> @@ -149,3 +149,6 @@
>  #if !__has_builtin (__is_reference)
>  # error "__has_builtin (__is_reference) failed"
>  #endif
> +#if !__has_builtin (__is_function)
> +# error "__has_builtin (__is_function) failed"
> +#endif
> diff --git a/gcc/testsuite/g++.dg/ext/is_function.C b/gcc/testsuite/g++.dg/ext/is_function.C
> new file mode 100644
> index 00000000000..2e1594b12ad
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/is_function.C
> @@ -0,0 +1,58 @@
> +// { dg-do compile { target c++11 } }
> +
> +#include <testsuite_tr1.h>
> +
> +using namespace __gnu_test;
> +
> +#define SA(X) static_assert((X),#X)
> +#define SA_TEST_CATEGORY(TRAIT, TYPE, EXPECT)	\
> +  SA(TRAIT(TYPE) == EXPECT);					\
> +  SA(TRAIT(const TYPE) == EXPECT);				\
> +  SA(TRAIT(volatile TYPE) == EXPECT);			\
> +  SA(TRAIT(const volatile TYPE) == EXPECT)
> +
> +struct A
> +{ void fn(); };
> +
> +template<typename>
> +struct AHolder { };
> +
> +template<class T, class U>
> +struct AHolder<U T::*>
> +{ using type = U; };
> +
> +// Positive tests.
> +SA(__is_function(int (int)));
> +SA(__is_function(ClassType (ClassType)));
> +SA(__is_function(float (int, float, int[], int&)));
> +SA(__is_function(int (int, ...)));
> +SA(__is_function(bool (ClassType) const));
> +SA(__is_function(AHolder<decltype(&A::fn)>::type));
> +
> +void fn();
> +SA(__is_function(decltype(fn)));
> +
> +// Negative tests.
> +SA_TEST_CATEGORY(__is_function, int, false);
> +SA_TEST_CATEGORY(__is_function, int*, false);
> +SA_TEST_CATEGORY(__is_function, int&, false);
> +SA_TEST_CATEGORY(__is_function, void, false);
> +SA_TEST_CATEGORY(__is_function, void*, false);
> +SA_TEST_CATEGORY(__is_function, void**, false);
> +SA_TEST_CATEGORY(__is_function, std::nullptr_t, false);
> +
> +SA_TEST_CATEGORY(__is_function, AbstractClass, false);
> +SA(!__is_function(int(&)(int)));
> +SA(!__is_function(int(*)(int)));
> +
> +SA_TEST_CATEGORY(__is_function, A, false);
> +SA_TEST_CATEGORY(__is_function, decltype(&A::fn), false);
> +
> +struct FnCallOverload
> +{ void operator()(); };
> +SA_TEST_CATEGORY(__is_function, FnCallOverload, false);
> +
> +// Sanity check.
> +SA_TEST_CATEGORY(__is_function, ClassType, false);
> +SA_TEST_CATEGORY(__is_function, IncompleteClass, false);
> +SA_TEST_CATEGORY(__is_function, IncompleteUnion, false);
> -- 
> 2.41.0
> 
>