c++/reflection: add null_reflection_p

I wanted to improve %E of info{}, and it seemed desirable to have a
shorter way to spell this test.

gcc/cp/ChangeLog:

	* reflect.cc (null_reflection_p): New.
	(splice): Use it.
	* error.cc (dump_expr): Use it.
	* cp-tree.h (null_reflection_p): Declare.

gcc/testsuite/ChangeLog:

	* g++.dg/reflect/pr125007.C: Add info{} test.

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 06dc5af495501dca2d2c1f68e66c194a7cfae1a7..8a168f509d40881664aaf3c13b12a479d76f5972 100644 (file)
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -9524,6 +9524,7 @@ extern tree process_metafunction (const constexpr_ctx *, tree, tree,
                                  bool *, bool *, tree *);
 extern tree get_reflection (location_t, tree, reflect_kind = REFLECT_UNDEF);
 extern tree get_null_reflection () ATTRIBUTE_PURE;
+extern bool null_reflection_p (const_tree) ATTRIBUTE_PURE;
 extern tree splice (tree);
 extern bool check_out_of_consteval_use (tree, bool = true);
 extern bool consteval_only_p (tree) ATTRIBUTE_PURE;

diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
index a22c8ee113e8ca4e4e30681f96bdaeb30791b931..c2fb6027c521e05322ed8503e7fb547603ceb4f9 100644 (file)
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -3471,6 +3471,11 @@ dump_expr (cxx_pretty_printer *pp, tree t, int flags)
            pp_right_paren (pp);
            break;
          default:
+           if (null_reflection_p (t))
+             {
+               pp_cxx_ws_string (pp, "std::meta::info{}");
+               break;
+             }
            pp_string (pp, "^^");
            pp->set_padding (pp_none);
            if (DECL_P (h))

diff --git a/gcc/cp/reflect.cc b/gcc/cp/reflect.cc
index ad4c77fab3eb13f01ebd22dbca9d666598a10fe6..c8148d9672632ef9177d6d455bc0e5c9b72a4343 100644 (file)
--- a/gcc/cp/reflect.cc
+++ b/gcc/cp/reflect.cc
@@ -267,6 +267,15 @@ get_null_reflection ()
   return null_reflection;
 }
 
+/* True iff T is a null reflection.  */
+
+bool
+null_reflection_p (const_tree t)
+{
+  return (t && TREE_CODE (t) == REFLECT_EXPR
+         && REFLECT_EXPR_HANDLE (t) == unknown_type_node);
+}
+
 /* Do strip_typedefs on T, but only for types.  */
 
 static tree
@@ -8533,7 +8542,7 @@ splice (tree refl)
       return error_mark_node;
     }
 
-  if (compare_reflections (refl, get_null_reflection ()))
+  if (null_reflection_p (refl))
     {
       error_at (loc, "cannot splice a null reflection");
       return error_mark_node;

diff --git a/gcc/testsuite/g++.dg/reflect/pr125007.C b/gcc/testsuite/g++.dg/reflect/pr125007.C
index 4ac0dfe03cc25464302227e9ab30c90ac529aa82..0939f940dfd6a054f9bd294191437a69a307fe3f 100644 (file)
--- a/gcc/testsuite/g++.dg/reflect/pr125007.C
+++ b/gcc/testsuite/g++.dg/reflect/pr125007.C
@@ -44,3 +44,6 @@ void qux (int x, int y);
 
 static_assert (parameters_of (^^qux)[0] == parameters_of (^^qux)[1]);  // { dg-error "static assertion failed" }
 // { dg-message "note: the comparison reduces to '\\\(parameters_of\\\(\\\^\\\^qux\\\(int, int\\\)\\\)\\\[0\\\] \\\{aka x\\\} == parameters_of\\\(\\\^\\\^qux\\\(int, int\\\)\\\)\\\[1\\\] \\\{aka y\\\}\\\)'" "" { target *-*-* } .-1 }
+
+static_assert (std::meta::info{} == ^^int);    // { dg-error "static assertion failed" }
+// { dg-message {note: the comparison reduces to '\(std::meta::info{} == \^\^int\)} "" { target *-*-* } .-1 }