On Tue, Sep 28, 2021 at 03:33:35PM -0400, Jason Merrill wrote:
> > > According to the function comment for defaulted_late_check, won't
> > > COMPLETE_TYPE_P (ctx) always be false here?
>
> Not for a function defaulted outside the class.
>
> > If so, I wonder if we could get away with moving this entire fragment
> > from defaulted_late_check to finish_struct_1 instead of calling
> > defaulted_late_check from finish_struct_1.
>
> The comment in check_bases_and_members says that we call it there so that
> it's before we clone [cd]tors. Probably better to leave the call there for
> other functions, just skip it for comparisons.
So like this instead then? Just tested with dg.exp=*spaceship* so far.
2021-09-28 Jakub Jelinek <ja...@redhat.com>
PR c++/102490
* method.c (defaulted_late_check): Don't synthetize constexpr
defaulted comparisons.
(finish_struct_1): Synthetize constexpr defaulted comparisons here
after layout_class_type.
* g++.dg/cpp2a/spaceship-eq11.C: New test.
* g++.dg/cpp2a/spaceship-eq12.C: New test.
--- gcc/cp/method.c.jj 2021-09-28 11:34:10.165412477 +0200
+++ gcc/cp/method.c 2021-09-28 22:28:23.637981709 +0200
@@ -3158,18 +3158,7 @@ defaulted_late_check (tree fn)
special_function_kind kind = special_function_p (fn);
if (kind == sfk_comparison)
- {
- /* If the function was declared constexpr, check that the definition
- qualifies. Otherwise we can define the function lazily. */
- if (DECL_DECLARED_CONSTEXPR_P (fn) && !DECL_INITIAL (fn))
- {
- /* Prevent GC. */
- function_depth++;
- synthesize_method (fn);
- function_depth--;
- }
- return;
- }
+ return;
bool fn_const_p = (copy_fn_p (fn) == 2);
tree implicit_fn = implicitly_declare_fn (kind, ctx, fn_const_p,
--- gcc/cp/class.c.jj 2021-09-28 11:34:10.096413431 +0200
+++ gcc/cp/class.c 2021-09-28 22:29:59.072669058 +0200
@@ -7467,7 +7467,21 @@ finish_struct_1 (tree t)
for any static member objects of the type we're working on. */
for (x = TYPE_FIELDS (t); x; x = DECL_CHAIN (x))
if (DECL_DECLARES_FUNCTION_P (x))
- DECL_IN_AGGR_P (x) = false;
+ {
+ /* Synthetize constexpr defaulted comparisons. */
+ if (!DECL_ARTIFICIAL (x)
+ && DECL_DEFAULTED_IN_CLASS_P (x)
+ && special_function_p (x) == sfk_comparison
+ && DECL_DECLARED_CONSTEXPR_P (x)
+ && !DECL_INITIAL (x))
+ {
+ /* Prevent GC. */
+ function_depth++;
+ synthesize_method (x);
+ function_depth--;
+ }
+ DECL_IN_AGGR_P (x) = false;
+ }
else if (VAR_P (x) && TREE_STATIC (x)
&& TREE_TYPE (x) != error_mark_node
&& same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (x)), t))
--- gcc/testsuite/g++.dg/cpp2a/spaceship-eq11.C.jj 2021-09-28
22:27:40.524574708 +0200
+++ gcc/testsuite/g++.dg/cpp2a/spaceship-eq11.C 2021-09-28 22:27:40.524574708
+0200
@@ -0,0 +1,43 @@
+// PR c++/102490
+// { dg-do run { target c++20 } }
+
+struct A
+{
+ unsigned char a : 1;
+ unsigned char b : 1;
+ constexpr bool operator== (const A &) const = default;
+};
+
+struct B
+{
+ unsigned char a : 8;
+ int : 0;
+ unsigned char b : 7;
+ constexpr bool operator== (const B &) const = default;
+};
+
+struct C
+{
+ unsigned char a : 3;
+ unsigned char b : 1;
+ constexpr bool operator== (const C &) const = default;
+};
+
+void
+foo (C &x, int y)
+{
+ x.b = y;
+}
+
+int
+main ()
+{
+ A a{}, b{};
+ B c{}, d{};
+ C e{}, f{};
+ a.b = 1;
+ d.b = 1;
+ foo (e, 0);
+ foo (f, 1);
+ return a == b || c == d || e == f;
+}
--- gcc/testsuite/g++.dg/cpp2a/spaceship-eq12.C.jj 2021-09-28
22:27:40.524574708 +0200
+++ gcc/testsuite/g++.dg/cpp2a/spaceship-eq12.C 2021-09-28 22:27:40.524574708
+0200
@@ -0,0 +1,5 @@
+// PR c++/102490
+// { dg-do run { target c++20 } }
+// { dg-options "-O2" }
+
+#include "spaceship-eq11.C"
Jakub
