On Thu, May 2, 2024 at 1:38 PM Jason Merrill <ja...@redhat.com> wrote:
>
> On 5/2/24 16:12, Ken Matsui wrote:
> > This patch implements built-in trait for std::is_invocable.
> >
> > gcc/cp/ChangeLog:
> >
> > * cp-trait.def: Define __is_invocable.
> > * constraint.cc (diagnose_trait_expr): Handle CPTK_IS_INVOCABLE.
> > * semantics.cc (trait_expr_value): Likewise.
> > (finish_trait_expr): Likewise.
> > * cp-tree.h (build_invoke): New function.
> > * method.cc (build_invoke): New function.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/ext/has-builtin-1.C: Test existence of __is_invocable.
> > * g++.dg/ext/is_invocable1.C: New test.
> > * g++.dg/ext/is_invocable2.C: New test.
> > * g++.dg/ext/is_invocable3.C: New test.
> > * g++.dg/ext/is_invocable4.C: New test.
> >
> > Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
> > ---
> > gcc/cp/constraint.cc | 6 +
> > gcc/cp/cp-trait.def | 1 +
> > gcc/cp/cp-tree.h | 2 +
> > gcc/cp/method.cc | 134 +++++++++
> > gcc/cp/semantics.cc | 5 +
> > gcc/testsuite/g++.dg/ext/has-builtin-1.C | 3 +
> > gcc/testsuite/g++.dg/ext/is_invocable1.C | 349 +++++++++++++++++++++++
> > gcc/testsuite/g++.dg/ext/is_invocable2.C | 139 +++++++++
> > gcc/testsuite/g++.dg/ext/is_invocable3.C | 51 ++++
> > gcc/testsuite/g++.dg/ext/is_invocable4.C | 33 +++
> > 10 files changed, 723 insertions(+)
> > create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable1.C
> > create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable2.C
> > create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable3.C
> > create mode 100644 gcc/testsuite/g++.dg/ext/is_invocable4.C
> >
> > diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> > index c28d7bf428e..6d14ef7dcc7 100644
> > --- a/gcc/cp/constraint.cc
> > +++ b/gcc/cp/constraint.cc
> > @@ -3792,6 +3792,12 @@ diagnose_trait_expr (tree expr, tree args)
> > case CPTK_IS_FUNCTION:
> > inform (loc, " %qT is not a function", t1);
> > break;
> > + case CPTK_IS_INVOCABLE:
> > + if (!t2)
> > + inform (loc, " %qT is not invocable", t1);
> > + else
> > + inform (loc, " %qT is not invocable by %qE", t1, t2);
> > + break;
> > case CPTK_IS_LAYOUT_COMPATIBLE:
> > inform (loc, " %qT is not layout compatible with %qT", t1, t2);
> > break;
> > diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
> > index b1c875a6e7d..4e420d5390a 100644
> > --- a/gcc/cp/cp-trait.def
> > +++ b/gcc/cp/cp-trait.def
> > @@ -75,6 +75,7 @@ DEFTRAIT_EXPR (IS_EMPTY, "__is_empty", 1)
> > DEFTRAIT_EXPR (IS_ENUM, "__is_enum", 1)
> > DEFTRAIT_EXPR (IS_FINAL, "__is_final", 1)
> > DEFTRAIT_EXPR (IS_FUNCTION, "__is_function", 1)
> > +DEFTRAIT_EXPR (IS_INVOCABLE, "__is_invocable", -1)
> > DEFTRAIT_EXPR (IS_LAYOUT_COMPATIBLE, "__is_layout_compatible", 2)
> > DEFTRAIT_EXPR (IS_LITERAL_TYPE, "__is_literal_type", 1)
> > DEFTRAIT_EXPR (IS_MEMBER_FUNCTION_POINTER,
> > "__is_member_function_pointer", 1)
> > diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
> > index 1938ada0268..83dc20e1130 100644
> > --- a/gcc/cp/cp-tree.h
> > +++ b/gcc/cp/cp-tree.h
> > @@ -7338,6 +7338,8 @@ extern tree get_copy_assign
> > (tree);
> > extern tree get_default_ctor (tree);
> > extern tree get_dtor (tree,
> > tsubst_flags_t);
> > extern tree build_stub_object (tree);
> > +extern tree build_invoke (tree, const_tree,
> > + tsubst_flags_t);
> > extern tree strip_inheriting_ctors (tree);
> > extern tree inherited_ctor_binfo (tree);
> > extern bool base_ctor_omit_inherited_parms (tree);
> > diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
> > index 08a3d34fb01..faf932258e6 100644
> > --- a/gcc/cp/method.cc
> > +++ b/gcc/cp/method.cc
> > @@ -1928,6 +1928,140 @@ build_trait_object (tree type)
> > return build_stub_object (type);
> > }
> >
> > +/* [func.require] Build an expression of INVOKE(FN_TYPE, ARG_TYPES...).
> > If the
> > + given is not invocable, returns error_mark_node. */
> > +
> > +tree
> > +build_invoke (tree fn_type, const_tree arg_types, tsubst_flags_t complain)
> > +{
> > + if (error_operand_p (fn_type) || error_operand_p (arg_types))
> > + return error_mark_node;
> > +
> > + gcc_assert (TYPE_P (fn_type));
> > + gcc_assert (TREE_CODE (arg_types) == TREE_VEC);
> > +
> > + /* Access check is required to determine if the given is invocable. */
> > + deferring_access_check_sentinel acs (dk_no_deferred);
> > +
> > + /* INVOKE is an unevaluated context. */
> > + cp_unevaluated cp_uneval_guard;
> > +
> > + bool is_ptrdatamem;
> > + bool is_ptrmemfunc;
> > + if (TREE_CODE (fn_type) == REFERENCE_TYPE)
> > + {
> > + tree deref_fn_type = TREE_TYPE (fn_type);
> > + is_ptrdatamem = TYPE_PTRDATAMEM_P (deref_fn_type);
> > + is_ptrmemfunc = TYPE_PTRMEMFUNC_P (deref_fn_type);
> > +
> > + /* Dereference fn_type if it is a pointer to member. */
> > + if (is_ptrdatamem || is_ptrmemfunc)
> > + fn_type = deref_fn_type;
> > + }
> > + else
> > + {
> > + is_ptrdatamem = TYPE_PTRDATAMEM_P (fn_type);
> > + is_ptrmemfunc = TYPE_PTRMEMFUNC_P (fn_type);
> > + }
> > +
> > + if (is_ptrdatamem && TREE_VEC_LENGTH (arg_types) != 1)
> > + {
> > + if (complain & tf_error)
> > + error ("pointer to data member type %qT can only be invoked with "
> > + "one argument", fn_type);
> > + return error_mark_node;
> > + }
> > +
> > + if (is_ptrmemfunc && TREE_VEC_LENGTH (arg_types) == 0)
> > + {
> > + if (complain & tf_error)
> > + error ("pointer to member function type %qT must be invoked with "
> > + "at least one argument", fn_type);
> > + return error_mark_node;
> > + }
> > +
> > + /* Construct an expression of a pointer to member. */
> > + tree ptrmem_expr;
> > + if (is_ptrdatamem || is_ptrmemfunc)
> > + {
> > + tree datum_type = TREE_VEC_ELT (arg_types, 0);
> > +
> > + /* datum must be a class type or a reference/pointer to a class
> > type. */
> > + if (!(CLASS_TYPE_P (datum_type)
> > + || ((TYPE_REF_P (datum_type) || POINTER_TYPE_P (datum_type))
> > + && CLASS_TYPE_P (TREE_TYPE (datum_type)))))
> > + {
> > + if (complain & tf_error)
> > + error ("first argument type %qT of a pointer to member must be"
> > + "a class type or a reference/pointer to a class type",
> > + datum_type);
> > + return error_mark_node;
> > + }
> > +
> > + bool is_refwrap = false;
> > + if (CLASS_TYPE_P (datum_type))
> > + {
> > + /* 1.2 & 1.5: Handle std::reference_wrapper. */
> > + tree datum_decl = TYPE_NAME (TYPE_MAIN_VARIANT (datum_type));
> > + if (decl_in_std_namespace_p (datum_decl))
> > + {
> > + const_tree name = DECL_NAME (datum_decl);
> > + if (name && (id_equal (name, "reference_wrapper")))
> > + {
> > + /* Retrieve T from std::reference_wrapper<T>,
> > + i.e., decltype(datum.get()). */
> > + datum_type = TREE_VEC_ELT (TYPE_TI_ARGS (datum_type), 0);
> > + is_refwrap = true;
> > + }
> > + }
> > + }
> > +
> > + tree ptrmem_class_type = TYPE_PTRMEM_CLASS_TYPE (fn_type);
> > + const bool ptrmem_is_base_of_datum =
> > + (NON_UNION_CLASS_TYPE_P (ptrmem_class_type)
> > + && NON_UNION_CLASS_TYPE_P (datum_type)
>
> Why NON_UNION? That doesn't seem to be based on anything in the standard.
>
> This check and the one for reference_wrapper need to ignore
> REFERENCE_TYPE; INVOKE is defined in terms of expressions, and the type
> of an expression is never a reference.
I think ptrmem_is_base_of_datum and is_refwrap checks are ignoring
REFERENCE_TYPE, leading to false, ...
>
> > + && (same_type_ignoring_top_level_qualifiers_p (ptrmem_class_type,
> > + datum_type)
> > + || DERIVED_FROM_P (ptrmem_class_type, datum_type)));
> > +
> > + tree datum_expr = build_trait_object (datum_type);
> > + if (!ptrmem_is_base_of_datum && !is_refwrap && !TYPE_REF_P
> > (datum_type))
... which is why I think we need to check TYPE_REF_P here.
>
> ...so we shouldn't need to check TYPE_REF_P here.
>
> Jason
>
> > + /* 1.3 & 1.6: Try to dereference datum_expr. */
> > + datum_expr = build_x_indirect_ref (UNKNOWN_LOCATION, datum_expr,
> > + RO_UNARY_STAR, NULL_TREE,
> > complain);
> > + /* 1.1, 1.2, 1.4, & 1.5: Otherwise. */
> > +
> > + tree fn_expr = build_trait_object (fn_type);
> > + ptrmem_expr = build_m_component_ref (datum_expr, fn_expr, complain);
> > +
> > + if (error_operand_p (ptrmem_expr))
> > + return error_mark_node;
> > +
> > + if (is_ptrdatamem)
> > + return ptrmem_expr;
> > + }
> > +
> > + /* Construct expressions for arguments to INVOKE. For a pointer to
> > member
> > + function, the first argument, which is the object, is not arguments to
> > + the function. */
> > + releasing_vec args;
> > + for (int i = is_ptrmemfunc ? 1 : 0; i < TREE_VEC_LENGTH (arg_types); ++i)
> > + {
> > + tree arg_type = TREE_VEC_ELT (arg_types, i);
> > + tree arg = build_trait_object (arg_type);
> > + vec_safe_push (args, arg);
> > + }
> > +
> > + tree invoke_expr;
> > + if (is_ptrmemfunc)
> > + invoke_expr = build_offset_ref_call_from_tree (ptrmem_expr, &args,
> > + complain);
> > + else /* 1.7. */
> > + invoke_expr = finish_call_expr (build_trait_object (fn_type), &args,
> > false,
> > + false, complain);
> > + return invoke_expr;
> > +}
> > +
> > /* Determine which function will be called when looking up NAME in TYPE,
> > called with a single ARGTYPE argument, or no argument if ARGTYPE is
> > null. FLAGS and COMPLAIN are as for build_new_method_call.
>
