[PATCH v14 25/26] c++: Implement __is_nothrow_invocable built-in trait

[Jason Merrill]

On 2/28/24 11:26, Ken Matsui wrote:
> This patch implements built-in trait for std::is_nothrow_invocable.

OK after addressing comments on other traits.

> gcc/cp/ChangeLog:
> 
> 	* cp-trait.def: Define __is_nothrow_invocable.
> 	* constraint.cc (diagnose_trait_expr): Handle
> 	CPTK_IS_NOTHROW_INVOCABLE.
> 	* semantics.cc (trait_expr_value): Likewise.
> 	(finish_trait_expr): Likewise.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/ext/has-builtin-1.C: Test existence of
> 	__is_nothrow_invocable.
> 	* g++.dg/ext/is_nothrow_invocable.C: New test.
> 
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>   gcc/cp/constraint.cc                          |  6 ++
>   gcc/cp/cp-trait.def                           |  1 +
>   gcc/cp/semantics.cc                           |  4 ++
>   gcc/testsuite/g++.dg/ext/has-builtin-1.C      |  3 +
>   .../g++.dg/ext/is_nothrow_invocable.C         | 62 +++++++++++++++++++
>   5 files changed, 76 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/ext/is_nothrow_invocable.C
> 
> diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> index c87b126fdb1..43d4f2102d6 100644
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -3824,6 +3824,12 @@ diagnose_trait_expr (tree expr, tree args)
>       case CPTK_IS_NOTHROW_CONVERTIBLE:
>   	  inform (loc, "  %qT is not nothrow convertible from %qE", t2, t1);
>         break;
> +    case CPTK_IS_NOTHROW_INVOCABLE:
> +	if (!t2)
> +	  inform (loc, "  %qT is not nothrow invocable", t1);
> +	else
> +	  inform (loc, "  %qT is not nothrow invocable by %qE", t1, t2);
> +	break;
>       case CPTK_IS_OBJECT:
>         inform (loc, "  %qT is not an object type", t1);
>         break;
> diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> index 6cb2b55f4ea..a9714921e94 100644
> --- a/gcc/cp/cp-trait.def
> +++ b/gcc/cp/cp-trait.def
> @@ -84,6 +84,7 @@ DEFTRAIT_EXPR (IS_MEMBER_POINTER, "__is_member_pointer", 1)
>   DEFTRAIT_EXPR (IS_NOTHROW_ASSIGNABLE, "__is_nothrow_assignable", 2)
>   DEFTRAIT_EXPR (IS_NOTHROW_CONSTRUCTIBLE, "__is_nothrow_constructible", -1)
>   DEFTRAIT_EXPR (IS_NOTHROW_CONVERTIBLE, "__is_nothrow_convertible", 2)
> +DEFTRAIT_EXPR (IS_NOTHROW_INVOCABLE, "__is_nothrow_invocable", -1)
>   DEFTRAIT_EXPR (IS_OBJECT, "__is_object", 1)
>   DEFTRAIT_EXPR (IS_POINTER_INTERCONVERTIBLE_BASE_OF, "__is_pointer_interconvertible_base_of", 2)
>   DEFTRAIT_EXPR (IS_POD, "__is_pod", 1)
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 149c0631d62..dba7b43a109 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -12494,6 +12494,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
>       case CPTK_IS_NOTHROW_CONVERTIBLE:
>         return is_nothrow_convertible (type1, type2);
>   
> +    case CPTK_IS_NOTHROW_INVOCABLE:
> +      return expr_noexcept_p (build_invoke (type1, type2, tf_none), tf_none);
> +
>       case CPTK_IS_OBJECT:
>         return (type_code1 != FUNCTION_TYPE
>   	      && type_code1 != REFERENCE_TYPE
> @@ -12689,6 +12692,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
>       case CPTK_IS_NOTHROW_ASSIGNABLE:
>       case CPTK_IS_NOTHROW_CONSTRUCTIBLE:
>       case CPTK_IS_NOTHROW_CONVERTIBLE:
> +    case CPTK_IS_NOTHROW_INVOCABLE:
>       case CPTK_IS_TRIVIALLY_ASSIGNABLE:
>       case CPTK_IS_TRIVIALLY_CONSTRUCTIBLE:
>       case CPTK_REF_CONSTRUCTS_FROM_TEMPORARY:
> diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> index d2a7ebdf25c..624d3525f27 100644
> --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> @@ -131,6 +131,9 @@
>   #if !__has_builtin (__is_nothrow_convertible)
>   # error "__has_builtin (__is_nothrow_convertible) failed"
>   #endif
> +#if !__has_builtin (__is_nothrow_invocable)
> +# error "__has_builtin (__is_nothrow_invocable) failed"
> +#endif
>   #if !__has_builtin (__is_object)
>   # error "__has_builtin (__is_object) failed"
>   #endif
> diff --git a/gcc/testsuite/g++.dg/ext/is_nothrow_invocable.C b/gcc/testsuite/g++.dg/ext/is_nothrow_invocable.C
> new file mode 100644
> index 00000000000..2f9b40e5538
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/is_nothrow_invocable.C
> @@ -0,0 +1,62 @@
> +// { dg-do compile { target c++11 } }
> +
> +#define SA(X) static_assert((X),#X)
> +
> +using func_type = void(*)();
> +SA( ! __is_nothrow_invocable(func_type) );
> +
> +#if __cpp_noexcept_function_type
> +using func_type_nt = void(*)() noexcept;
> +SA(   __is_nothrow_invocable(func_type_nt) );
> +#endif
> +
> +struct X { };
> +using mem_type = int X::*;
> +
> +SA( ! __is_nothrow_invocable(mem_type) );
> +SA( ! __is_nothrow_invocable(mem_type, int) );
> +SA( ! __is_nothrow_invocable(mem_type, int&) );
> +SA(   __is_nothrow_invocable(mem_type, X&) );
> +
> +using memfun_type = int (X::*)();
> +
> +SA( ! __is_nothrow_invocable(memfun_type) );
> +SA( ! __is_nothrow_invocable(memfun_type, int) );
> +SA( ! __is_nothrow_invocable(memfun_type, int&) );
> +SA( ! __is_nothrow_invocable(memfun_type, X&) );
> +SA( ! __is_nothrow_invocable(memfun_type, X*) );
> +
> +#if __cpp_noexcept_function_type
> +using memfun_type_nt = int (X::*)() noexcept;
> +
> +SA( ! __is_nothrow_invocable(memfun_type_nt) );
> +SA( ! __is_nothrow_invocable(memfun_type_nt, int) );
> +SA( ! __is_nothrow_invocable(memfun_type_nt, int&) );
> +SA(   __is_nothrow_invocable(memfun_type_nt, X&) );
> +SA(   __is_nothrow_invocable(memfun_type_nt, X*) );
> +#endif
> +
> +struct F {
> +  int& operator()();
> +  long& operator()() const noexcept;
> +  short& operator()(int) &&;
> +  char& operator()(int) const& noexcept;
> +private:
> +  void operator()(int, int) noexcept;
> +};
> +using CF = const F;
> +
> +SA( ! __is_nothrow_invocable(F ) );
> +SA(   __is_nothrow_invocable(CF) );
> +
> +SA( ! __is_nothrow_invocable(F,   int) );
> +SA(   __is_nothrow_invocable(F&,  int) );
> +
> +SA(   __is_nothrow_invocable(CF,   int) );
> +SA(   __is_nothrow_invocable(CF&,  int) );
> +SA( ! __is_nothrow_invocable(F, int, int) );
> +
> +struct FX {
> +  X operator()() const noexcept { return {}; }
> +};
> +SA(   __is_nothrow_invocable(FX) );