From 30556bf81f4385c2a9c449948865dbcf35664764 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Wed, 8 Mar 2023 23:53:21 -0500
Subject: [PATCH] c++: hide __is_deducible for GCC 13
I want to have more discussion about the interface before claiming the
__is_deducible name, so for GCC 13 make it internal-only.
gcc/ChangeLog:
* doc/extend.texi: Comment out __is_deducible docs.
gcc/cp/ChangeLog:
* cp-trait.def (IS_DEDUCIBLE): Add space to name.
gcc/testsuite/ChangeLog:
* g++.dg/ext/is_deducible1.C: Guard with
__has_builtin (__is_deducible).
---
gcc/cp/cp-trait.def | 3 ++-
gcc/doc/extend.texi | 7 ++++---
gcc/testsuite/g++.dg/ext/is_deducible1.C | 6 +++++-
3 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index e43fb464f42b..bac593c00945 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -84,7 +84,8 @@ DEFTRAIT_EXPR (IS_TRIVIALLY_COPYABLE, "__is_trivially_copyable", 1)
DEFTRAIT_EXPR (IS_UNION, "__is_union", 1)
DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY, "__reference_constructs_from_temporary", 2)
DEFTRAIT_EXPR (REF_CONVERTS_FROM_TEMPORARY, "__reference_converts_from_temporary", 2)
-DEFTRAIT_EXPR (IS_DEDUCIBLE, "__is_deducible", 2)
+/* FIXME Added space to avoid direct usage in GCC 13. */
+DEFTRAIT_EXPR (IS_DEDUCIBLE, "__is_deducible ", 2)
DEFTRAIT_TYPE (REMOVE_CV, "__remove_cv", 1)
DEFTRAIT_TYPE (REMOVE_REFERENCE, "__remove_reference", 1)
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b64a85722dbc..9dcfc860108f 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -25213,9 +25213,10 @@ type. A diagnostic is produced if this requirement is not met.
If @code{type} is a cv-qualified class type, and not a union type
([basic.compound]) the trait is @code{true}, else it is @code{false}.
-@item __is_deducible (template, type)
-If template arguments for @code{template} can be deduced from
-@code{type} or obtained from default template arguments.
+@c FIXME Commented out for GCC 13, discuss user interface for GCC 14.
+@c @item __is_deducible (template, type)
+@c If template arguments for @code{template} can be deduced from
+@c @code{type} or obtained from default template arguments.
@item __is_empty (type)
If @code{__is_class (type)} is @code{false} then the trait is @code{false}.
diff --git a/gcc/testsuite/g++.dg/ext/is_deducible1.C b/gcc/testsuite/g++.dg/ext/is_deducible1.C
index 30cbe089f507..6873e4f4c2e6 100644
--- a/gcc/testsuite/g++.dg/ext/is_deducible1.C
+++ b/gcc/testsuite/g++.dg/ext/is_deducible1.C
@@ -1,5 +1,7 @@
// { dg-do compile { target c++20 } }
+#if __has_builtin (__is_deducible)
+
template <class T> struct A { };
template <class T> struct B { };
@@ -26,6 +28,8 @@ static_assert (__is_deducible (D, D<int>));
template <class T, T N> using E = int[N];
static_assert (__is_deducible (E, int[42]));
+#endif // __has_builtin (__is_deducible)
+
// We don't try to support this.
template <class T> void f(T);
-bool b = __is_deducible (f, void (int)); // { dg-error "class or alias" }
+bool b = __is_deducible (f, void (int)); // { dg-error "" }
--
GitLab