On Mon, Jan 13, 2025 at 08:35:57PM -0500, Jason Merrill wrote:
> I'd rather hoist the build_static_cast from later; the rules for static cast
> aren't quite the same as can_convert. See:
>
> > if (defining)
> > {
> > tree val;
> > if (code == EQ_EXPR)
> > val = boolean_true_node;
> > else
> > {
> > tree seql = lookup_comparison_result (cc_strong_ordering,
> > "equal", complain);
> > val = build_static_cast (input_location, rettype, seql,
> > complain);
>
> Apparently this also needs to happen when !defining.
Ok, so like this then?
2025-01-14 Jakub Jelinek <ja...@redhat.com>
PR c++/118387
* method.cc (build_comparison_op): Set bad if
std::strong_ordering::equal doesn't convert to rettype.
* g++.dg/cpp2a/spaceship-err6.C: Expect another error.
* g++.dg/cpp2a/spaceship-synth17.C: Likewise.
* g++.dg/cpp2a/spaceship-synth-neg6.C: Likewise.
* g++.dg/cpp2a/spaceship-synth-neg7.C: New test.
* testsuite/25_algorithms/default_template_value.cc
(Input::operator<=>): Use auto as return type rather than bool.
--- gcc/cp/method.cc.jj 2025-01-11 21:58:05.387588681 +0100
+++ gcc/cp/method.cc 2025-01-14 09:45:14.064303749 +0100
@@ -1635,6 +1635,18 @@ build_comparison_op (tree fndecl, bool d
rettype = common_comparison_type (comps);
apply_deduced_return_type (fndecl, rettype);
}
+ tree retvaleq;
+ if (code == EQ_EXPR)
+ retvaleq = boolean_true_node;
+ else
+ {
+ tree seql = lookup_comparison_result (cc_strong_ordering,
+ "equal", complain);
+ retvaleq = build_static_cast (input_location, rettype, seql,
+ complain);
+ if (retvaleq == error_mark_node)
+ bad = true;
+ }
if (bad)
{
DECL_DELETED_FN (fndecl) = true;
@@ -1722,19 +1734,7 @@ build_comparison_op (tree fndecl, bool d
}
}
if (defining)
- {
- tree val;
- if (code == EQ_EXPR)
- val = boolean_true_node;
- else
- {
- tree seql = lookup_comparison_result (cc_strong_ordering,
- "equal", complain);
- val = build_static_cast (input_location, rettype, seql,
- complain);
- }
- finish_return_stmt (val);
- }
+ finish_return_stmt (retvaleq);
}
else if (code == NE_EXPR)
{
--- gcc/testsuite/g++.dg/cpp2a/spaceship-err6.C.jj 2021-04-14
19:19:14.050804249 +0200
+++ gcc/testsuite/g++.dg/cpp2a/spaceship-err6.C 2025-01-14 10:27:12.311540443
+0100
@@ -10,7 +10,7 @@ class MyClass
public:
MyClass(int value): mValue(value) {}
- bool operator<=>(const MyClass&) const = default;
+ bool operator<=>(const MyClass&) const = default; // { dg-error "invalid
'static_cast' from type 'const std::strong_ordering' to type 'bool'" }
};
int main()
--- gcc/testsuite/g++.dg/cpp2a/spaceship-synth17.C.jj 2025-01-11
21:58:05.460587663 +0100
+++ gcc/testsuite/g++.dg/cpp2a/spaceship-synth17.C 2025-01-14
10:32:00.246561725 +0100
@@ -8,7 +8,7 @@ struct B {};
struct A
{
B b; // { dg-error "no match for 'operator<=>' in
'\[^\n\r]*' \\\(operand types are 'B' and 'B'\\\)" }
- int operator<=> (const A &) const = default;
+ int operator<=> (const A &) const = default; // { dg-error "invalid
'static_cast' from type 'const std::strong_ordering' to type 'int'" }
};
int
--- gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg6.C.jj 2021-08-12
20:37:12.696473756 +0200
+++ gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg6.C 2025-01-14
10:27:49.739023268 +0100
@@ -5,7 +5,7 @@
struct S {
int a; // { dg-error "three-way comparison of 'S::a'
has type 'std::strong_ordering', which does not convert to 'int\\*'" }
- int *operator<=>(const S&) const = default;
+ int *operator<=>(const S&) const = default; // { dg-error "invalid
'static_cast' from type 'const std::strong_ordering' to type 'int\\*'" }
};
bool b = S{} < S{}; // { dg-error "use of deleted function
'constexpr int\\* S::operator<=>\\\(const S&\\\) const'" }
--- gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg7.C.jj 2025-01-13
16:19:09.897650742 +0100
+++ gcc/testsuite/g++.dg/cpp2a/spaceship-synth-neg7.C 2025-01-14
10:31:31.802954766 +0100
@@ -0,0 +1,58 @@
+// PR c++/118387
+// { dg-do compile { target c++20 } }
+
+#include <compare>
+
+struct A {
+ int operator<=> (const A &) const;
+};
+
+struct B {
+ A a;
+ int operator<=> (const B &) const = default; // { dg-message "'constexpr int
B::operator<=>\\\(const B&\\\) const' is implicitly deleted because the default
definition would be ill-formed:" }
+}; // { dg-error "invalid 'static_cast' from type 'const
std::strong_ordering' to type 'int'" "" { target *-*-* } .-1 }
+
+struct C {
+ int operator<=> (const C &) const = default; // { dg-message "'constexpr int
C::operator<=>\\\(const C&\\\) const' is implicitly deleted because the default
definition would be ill-formed:" }
+}; // { dg-error "invalid 'static_cast' from type 'const
std::strong_ordering' to type 'int'" "" { target *-*-* } .-1 }
+
+struct D {
+ auto operator<=> (const D &) const = default;
+};
+
+struct E {
+ D a; // { dg-error "three-way comparison of 'E::a' has type
'std::strong_ordering', which does not convert to 'int'" }
+ int operator<=> (const E &) const = default; // { dg-message "'constexpr int
E::operator<=>\\\(const E&\\\) const' is implicitly deleted because the default
definition would be ill-formed:" }
+}; // { dg-error "invalid 'static_cast' from type 'const
std::strong_ordering' to type 'int'" "" { target *-*-* } .-1 }
+
+struct F {
+ A a;
+ int operator<=> (const F &) const = default;
+};
+
+struct G {
+ int operator<=> (const G &) const = default;
+};
+
+struct H {
+ D a;
+ int operator<=> (const H &) const = default;
+};
+
+auto
+foo (B a, B b)
+{
+ return a <=> b; // { dg-error "use of deleted function 'constexpr int
B::operator<=>\\\(const B&\\\) const'" }
+}
+
+auto
+bar (C a, C b)
+{
+ return a <=> b; // { dg-error "use of deleted function 'constexpr int
C::operator<=>\\\(const C&\\\) const'" }
+}
+
+auto
+baz (E a, E b)
+{
+ return a <=> b; // { dg-error "use of deleted function 'constexpr int
E::operator<=>\\\(const E&\\\) const'" }
+}
--- libstdc++-v3/testsuite/25_algorithms/default_template_value.cc.jj
2024-09-24 15:14:54.199160911 +0200
+++ libstdc++-v3/testsuite/25_algorithms/default_template_value.cc
2025-01-14 10:40:02.304872699 +0100
@@ -27,7 +27,7 @@ struct Output
struct Input
{
Input(int, double);
- friend bool operator<=>(const Input &, const Input &) = default;
+ friend auto operator<=>(const Input &, const Input &) = default;
friend Input operator+(const Input &, const Input &);
operator Output() const;
};
Jakub
