[PATCH v14 15/26] c++: Implement __add_lvalue_reference built-in trait

[Jason Merrill]

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

OK.

> gcc/cp/ChangeLog:
> 
> 	* cp-trait.def: Define __add_lvalue_reference.
> 	* semantics.cc (finish_trait_type): Handle
> 	CPTK_ADD_LVALUE_REFERENCE.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/ext/has-builtin-1.C: Test existence of
> 	__add_lvalue_reference.
> 	* g++.dg/ext/add_lvalue_reference.C: New test.
> 
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>   gcc/cp/cp-trait.def                           |  1 +
>   gcc/cp/semantics.cc                           |  8 +++++++
>   .../g++.dg/ext/add_lvalue_reference.C         | 21 +++++++++++++++++++
>   gcc/testsuite/g++.dg/ext/has-builtin-1.C      |  3 +++
>   4 files changed, 33 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/ext/add_lvalue_reference.C
> 
> diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> index 933c8bcbe68..9a27dca4ea3 100644
> --- a/gcc/cp/cp-trait.def
> +++ b/gcc/cp/cp-trait.def
> @@ -48,6 +48,7 @@
>   #define DEFTRAIT_TYPE_DEFAULTED
>   #endif
>   
> +DEFTRAIT_TYPE (ADD_LVALUE_REFERENCE, "__add_lvalue_reference", 1)
>   DEFTRAIT_TYPE (ADD_POINTER, "__add_pointer", 1)
>   DEFTRAIT_EXPR (HAS_NOTHROW_ASSIGN, "__has_nothrow_assign", 1)
>   DEFTRAIT_EXPR (HAS_NOTHROW_CONSTRUCTOR, "__has_nothrow_constructor", 1)
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 078424dac23..05f5b62f9df 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -12776,6 +12776,14 @@ finish_trait_type (cp_trait_kind kind, tree type1, tree type2,
>   
>     switch (kind)
>       {
> +    case CPTK_ADD_LVALUE_REFERENCE:
> +      if (VOID_TYPE_P (type1)
> +	  || (FUNC_OR_METHOD_TYPE_P (type1)
> +	      && (type_memfn_quals (type1) != TYPE_UNQUALIFIED
> +		  || type_memfn_rqual (type1) != REF_QUAL_NONE)))
> +	return type1;
> +      return cp_build_reference_type (type1, /*rval=*/false);
> +
>       case CPTK_ADD_POINTER:
>         if (FUNC_OR_METHOD_TYPE_P (type1)
>   	  && (type_memfn_quals (type1) != TYPE_UNQUALIFIED
> diff --git a/gcc/testsuite/g++.dg/ext/add_lvalue_reference.C b/gcc/testsuite/g++.dg/ext/add_lvalue_reference.C
> new file mode 100644
> index 00000000000..8fe1e0300e5
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/add_lvalue_reference.C
> @@ -0,0 +1,21 @@
> +// { dg-do compile { target c++11 } }
> +
> +#define SA(X) static_assert((X),#X)
> +
> +class ClassType { };
> +
> +SA(__is_same(__add_lvalue_reference(int), int&));
> +SA(__is_same(__add_lvalue_reference(int&), int&));
> +SA(__is_same(__add_lvalue_reference(const int), const int&));
> +SA(__is_same(__add_lvalue_reference(int*), int*&));
> +SA(__is_same(__add_lvalue_reference(ClassType&), ClassType&));
> +SA(__is_same(__add_lvalue_reference(ClassType), ClassType&));
> +SA(__is_same(__add_lvalue_reference(int(int)), int(&)(int)));
> +SA(__is_same(__add_lvalue_reference(int&&), int&));
> +SA(__is_same(__add_lvalue_reference(ClassType&&), ClassType&));
> +SA(__is_same(__add_lvalue_reference(void), void));
> +SA(__is_same(__add_lvalue_reference(const void), const void));
> +SA(__is_same(__add_lvalue_reference(bool(int) const), bool(int) const));
> +SA(__is_same(__add_lvalue_reference(bool(int) &), bool(int) &));
> +SA(__is_same(__add_lvalue_reference(bool(int) const &&), bool(int) const &&));
> +SA(__is_same(__add_lvalue_reference(bool(int)), bool(&)(int)));
> diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> index 85b74bd676b..3fca9cfabcc 100644
> --- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> +++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
> @@ -2,6 +2,9 @@
>   // { dg-do compile }
>   // Verify that __has_builtin gives the correct answer for C++ built-ins.
>   
> +#if !__has_builtin (__add_lvalue_reference)
> +# error "__has_builtin (__add_lvalue_reference) failed"
> +#endif
>   #if !__has_builtin (__add_pointer)
>   # error "__has_builtin (__add_pointer) failed"
>   #endif