From dea470d09155f2007bdd502c16614128cb6f9348 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Sat, 19 Sep 2020 11:17:41 -0400 Subject: [PATCH] c++: std::is_constant_evaluated inside constraint [PR97051] According to [expr.const]/14, the result of substitution into an atomic constraint is manifestly constant-evaluated; this patch adjusts the call to maybe_constant_value in satisfy_atom to that effect. gcc/cp/ChangeLog: PR c++/97051 * constraint.cc (satisfy_atom): Pass true as the manifestly_const_eval argument to maybe_constant_value. gcc/testsuite/ChangeLog: PR c++/97051 * g++.dg/cpp2a/is-constant-evaluated11.C: New test. --- gcc/cp/constraint.cc | 3 ++- .../g++.dg/cpp2a/is-constant-evaluated11.C | 16 ++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated11.C diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc index 0aab3073cc1..8137df59e37 100644 --- a/gcc/cp/constraint.cc +++ b/gcc/cp/constraint.cc @@ -2643,7 +2643,8 @@ satisfy_atom (tree t, tree args, subst_info info) result = cxx_constant_value (result); else { - result = maybe_constant_value (result); + result = maybe_constant_value (result, NULL_TREE, + /*manifestly_const_eval=*/true); if (!TREE_CONSTANT (result)) result = error_mark_node; } diff --git a/gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated11.C b/gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated11.C new file mode 100644 index 00000000000..a31867f74fb --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated11.C @@ -0,0 +1,16 @@ +// PR c++/97051 +// { dg-do compile { target c++20 } } + +namespace std { + constexpr inline bool + is_constant_evaluated () noexcept + { + return __builtin_is_constant_evaluated (); + } +} + +template + requires (std::is_constant_evaluated()) +constexpr int a = 0; + +constexpr int b = a; -- 2.30.2