On 2/3/22 16:06, Patrick Palka wrote:
On Thu, 3 Feb 2022, Jason Merrill wrote:
On 2/3/22 14:58, Patrick Palka wrote:
When synthesizing a defaulted comparison op from
maybe_instantiate_noexcept, we seem to be forgetting to instantiate the
noexcept-spec afterwards.
Hmm, there shouldn't be any need to instantiate the noexcept-spec afterwards,
it should have been set by ~comp_info.
It appears the comp_info class sets the noexcept-spec only if the
comparison function hasn't been declared with an explicit noexcept-spec.
Otherwise the class doesn't touch the noexcept-spec, and it remains a
DEFERRED_NOEXCEPT with non-NULL DEFERRED_NOEXCEPT_PATTERN.
Ah, I see. So perhaps we should entirely skip the current
DECL_MAYBE_DELETED handling in maybe_instantiate_noexcept if we have
DEFERRED_NOEXCEPT with non-null DEFERRED_NOEXCEPT_PATTERN (which seems
to want another macro)?
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk and perhaps 11?
PR c++/96242
gcc/cp/ChangeLog:
* pt.cc (maybe_instantiate_noexcept): Keep going after
successfully synthesizing a DECL_MAYBE_DELETED fn.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/spaceship-synth15.C: New test.
---
gcc/cp/pt.cc | 3 ++-
.../g++.dg/cpp2a/spaceship-synth15.C | 22 +++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/spaceship-synth15.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 6dd64101ced..03345ed3ed3 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -25986,7 +25986,8 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t
complain)
++function_depth;
maybe_synthesize_method (fn);
--function_depth;
- return !DECL_MAYBE_DELETED (fn);
+ if (DECL_MAYBE_DELETED (fn))
+ return false;
}
tree fntype = TREE_TYPE (fn);
diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-synth15.C
b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth15.C
new file mode 100644
index 00000000000..00ea6c10474
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth15.C
@@ -0,0 +1,22 @@
+// PR c++/96242
+// { dg-do compile { target c++20 } }
+
+#include <compare>
+
+template<bool B>
+struct X {
+ auto operator<=>(const X&) const noexcept(B) = default;
+ bool operator==(const X&) const noexcept(!B) = default;
+};
+
+X<true> x_t;
+static_assert(noexcept(x_t <=> x_t));
+static_assert(noexcept(x_t < x_t));
+static_assert(!noexcept(x_t == x_t));
+static_assert(!noexcept(x_t != x_t));
+
+X<false> x_f;
+static_assert(!noexcept(x_f <=> x_f));
+static_assert(!noexcept(x_f < x_f));
+static_assert(noexcept(x_f == x_f));
+static_assert(noexcept(x_f != x_f));
