Tested on x86_64-pc-linux-gnu, does this look OK for trunk/16?
-- >8 --
Various reflection queries reject functions (or variables) with an
undeduced return type. But this assumes return type deduction has
already been attempted which is not the case if the function is a
specialization that has not yet been ODR-used or otherwise instantiated.
Similarly we can also have an uninstantiated noexcept which we should
also instantiate at this point.
Rather an inventing a new way to resolve the type of such a function
or variable for reflection purposes, I think we can just silently call
mark_used in an unevaluated context, making it behave similarly to
requires { &decl; }. Since diagnostics (in the immediate context) will
be suppressed it means we'll gracefully handle deleted functions or
those with unsatisfied constraints, leaving it up to the caller to
handle them.
PR c++/124628
gcc/cp/ChangeLog:
* reflect.cc (resolve_type_of_reflected_decl): New.
(get_reflection): Call resolve_type_of_reflected_decl instead
of mark_used.
(has_type): Call resolve_type_of_reflected_decl before
checking for an undeduced auto.
(eval_can_substitute): Likewise. Also look through BASELINK.
(members_of_representable): Call resolve_type_of_reflected_decl
before checking for an undeduced auto.
gcc/testsuite/ChangeLog:
* g++.dg/reflect/can_substitute2.C: New test.
* g++.dg/reflect/members_of14.C: New test.
* g++.dg/reflect/substitute3.C: Adjust test so that f<int>'s
return type fails to get deduced.
* g++.dg/reflect/type_of3.C: Extend test to check for
---
gcc/cp/reflect.cc | 32 ++++++++++++++++---
.../g++.dg/reflect/can_substitute2.C | 19 +++++++++++
gcc/testsuite/g++.dg/reflect/members_of14.C | 29 +++++++++++++++++
gcc/testsuite/g++.dg/reflect/substitute3.C | 4 +--
gcc/testsuite/g++.dg/reflect/type_of3.C | 6 ++++
5 files changed, 82 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/reflect/can_substitute2.C
create mode 100644 gcc/testsuite/g++.dg/reflect/members_of14.C
diff --git a/gcc/cp/reflect.cc b/gcc/cp/reflect.cc
index ad4c77fab3eb..96450a7ebb58 100644
--- a/gcc/cp/reflect.cc
+++ b/gcc/cp/reflect.cc
@@ -74,6 +74,19 @@ init_reflection ()
pop_namespace ();
}
+/* Ensure the type of DECL is fully resolved by performing return
+ type deduction and deferred noexcept instantiation. */
+
+static void
+resolve_type_of_reflected_decl (tree decl)
+{
+ cp_unevaluated u;
+ /* Quietly calling mark_used in an unevaluated context will perform
+ all necessary checks and instantiations while suppressing constraint
+ unsatisfaction and deletedness diagnostics. */
+ mark_used (decl, tf_none);
+}
+
/* Create a REFLECT_EXPR expression of kind KIND around T. */
static tree
@@ -210,8 +223,7 @@ get_reflection (location_t loc, tree t, reflect_kind
kind/*=REFLECT_UNDEF*/)
t = resolve_nondeduced_context_or_error (t, tf_warning_or_error);
/* The argument could have a deduced return type, so we need to
instantiate it now to find out its type. */
- if (!mark_used (t))
- return error_mark_node;
+ resolve_type_of_reflected_decl (t);
/* Avoid -Wunused-but-set* warnings when a variable or parameter
is just set and reflected. */
if (VAR_P (t) || TREE_CODE (t) == PARM_DECL)
@@ -2533,6 +2545,7 @@ has_type (tree r, reflect_kind kind)
{
if (DECL_CONSTRUCTOR_P (r) || DECL_DESTRUCTOR_P (r))
return false;
+ resolve_type_of_reflected_decl (r);
if (undeduced_auto_decl (r))
return false;
return true;
@@ -5532,7 +5545,12 @@ eval_can_substitute (location_t loc, const constexpr_ctx
*ctx,
if (fn == error_mark_node)
return boolean_false_node;
fn = resolve_nondeduced_context_or_error (fn, tf_none);
- if (fn == error_mark_node || undeduced_auto_decl (fn))
+ if (fn == error_mark_node)
+ return boolean_false_node;
+ if (BASELINK_P (fn))
+ fn = BASELINK_FUNCTIONS (fn);
+ resolve_type_of_reflected_decl (fn);
+ if (undeduced_auto_decl (fn))
return boolean_false_node;
return boolean_true_node;
}
@@ -6759,8 +6777,12 @@ members_of_representable_p (tree c, tree r)
|| TREE_CODE (r) == FIELD_DECL
|| TREE_CODE (r) == NAMESPACE_DECL)
return true;
- if (VAR_OR_FUNCTION_DECL_P (r) && !undeduced_auto_decl (r))
- return true;
+ if (VAR_OR_FUNCTION_DECL_P (r))
+ {
+ resolve_type_of_reflected_decl (r);
+ if (!undeduced_auto_decl (r))
+ return true;
+ }
}
return false;
}
diff --git a/gcc/testsuite/g++.dg/reflect/can_substitute2.C
b/gcc/testsuite/g++.dg/reflect/can_substitute2.C
new file mode 100644
index 000000000000..6628a1b72060
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/can_substitute2.C
@@ -0,0 +1,19 @@
+// [meta.reflection.substitute] Example 1
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+template<class T>
+auto fn1();
+
+static_assert(!can_substitute(^^fn1, {^^int}));
+constexpr auto r1 = substitute(^^fn1, {^^int}); // { dg-error "can_substitute
returned false" }
+
+template<class T>
+auto fn2() {
+ static_assert(false); // { dg-error "assert" }
+ return T{};
+}
+
+constexpr bool r2 = can_substitute(^^fn2, {^^int}); // { dg-message "required
from here" }
diff --git a/gcc/testsuite/g++.dg/reflect/members_of14.C
b/gcc/testsuite/g++.dg/reflect/members_of14.C
new file mode 100644
index 000000000000..6a969063aa4b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/members_of14.C
@@ -0,0 +1,29 @@
+// PR c++/124628
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+template<class T> void f();
+
+template<class T>
+struct A {
+ void g() noexcept(noexcept(T{}));
+ auto h() { return T{}; }
+ static inline auto m = T{};
+ // A& operator=(const A&) noexcept;
+ // A& operator=(A&&) noexcept;
+};
+
+int main() {
+ constexpr auto ac = std::meta::access_context::current();
+ template for (constexpr auto mem : define_static_array(members_of(^^A<int>,
ac)))
+ if constexpr (!is_constructor(mem) && !is_destructor(mem))
+ f<typename [:type_of(mem):]>();
+}
+
+// { dg-final { scan-assembler _Z1fIDoFvvEEvv } } void f<void () noexcept>()
+// { dg-final { scan-assembler _Z1fIFivEEvv } } void f<int ()>()
+// { dg-final { scan-assembler _Z1fIiEvv } } void f<int>()
+// { dg-final { scan-assembler _Z1fIDoFR1AIiERKS1_EEvv } } void f<A<int>&
(A<int> const&) noexcept>()
+// { dg-final { scan-assembler _Z1fIDoFR1AIiEOS1_EEvv } } void f<A<int>&
(A<int>&&) noexcept>()
diff --git a/gcc/testsuite/g++.dg/reflect/substitute3.C
b/gcc/testsuite/g++.dg/reflect/substitute3.C
index ff1b1aeaf4da..19329a80efea 100644
--- a/gcc/testsuite/g++.dg/reflect/substitute3.C
+++ b/gcc/testsuite/g++.dg/reflect/substitute3.C
@@ -7,9 +7,7 @@
template<typename>
auto
-f ()
-{
-}
+f ();
consteval bool
g ()
diff --git a/gcc/testsuite/g++.dg/reflect/type_of3.C
b/gcc/testsuite/g++.dg/reflect/type_of3.C
index ba28c4f59808..b739851da2e0 100644
--- a/gcc/testsuite/g++.dg/reflect/type_of3.C
+++ b/gcc/testsuite/g++.dg/reflect/type_of3.C
@@ -10,4 +10,10 @@ struct S {
};
int h() { return 0; }
+template<class T>
+struct ST {
+ auto g() { return T{}; }
+};
+
static_assert(type_of(^^S::g) == type_of(^^h));
+static_assert(type_of(^^ST<int>::g) == type_of(^^h));
--
2.54.0.rc1.54.g60f07c4f5c
