c++/reflection: fix wrong-code with members_of [PR124646, PR124645]

My r16-8235 change should have set DECL_EXTERNAL only in the
!at_function_scope_p block, before rest_of_decl_compilation.  Setting
DECL_EXTERNAL on the temporary var for both at_function_scope_p and
!at_function_scope_p cases causes issues: in members_of11.C, we wrongly
initialize 'mem' in the loop to A::a both times, insted of A::a and B::b.
Similarly in members_of12.C we wrongly initialize member when inspecting
ns2.

I couldn't track down where *exactly* things go wrong, but the point
of r16-8235 was to set DECL_EXTERNAL only for the rest_of_decl_compilation
call.

	PR c++/124646
	PR c++/124645

gcc/cp/ChangeLog:

	* call.cc (set_up_extended_ref_temp): Move setting DECL_EXTERNAL
	to the !at_function_scope_p block.

gcc/testsuite/ChangeLog:

	* g++.dg/reflect/members_of11.C: New test.
	* g++.dg/reflect/members_of12.C: New test.

Reviewed-by: Jason Merrill <jason@redhat.com>

diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 36703c587eb5aa60d7e929e12e66202c907f929e..92c3a23ab8d9c5bedf195d685d9b95e6bb086eab 100644 (file)
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -14351,10 +14351,6 @@ set_up_extended_ref_temp (tree decl, tree expr, vec<tree, va_gc> **cleanups,
   /* Any reference temp has a non-trivial initializer.  */
   DECL_NONTRIVIALLY_INITIALIZED_P (var) = true;
 
-  /* Don't output reflection variables.  */
-  if (consteval_only_p (var))
-    DECL_EXTERNAL (var) = true;
-
   /* If the initializer is constant, put it in DECL_INITIAL so we get
      static initialization and use in constant expressions.  */
   init = maybe_constant_init (expr, var, /*manifestly_const_eval=*/true);
@@ -14467,6 +14463,10 @@ set_up_extended_ref_temp (tree decl, tree expr, vec<tree, va_gc> **cleanups,
     }
   else
     {
+      /* Don't output reflection variables.  */
+      if (consteval_only_p (var))
+       DECL_EXTERNAL (var) = true;
+
       rest_of_decl_compilation (var, /*toplev=*/1, at_eof);
       if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type))
        {

diff --git a/gcc/testsuite/g++.dg/reflect/members_of11.C b/gcc/testsuite/g++.dg/reflect/members_of11.C
new file mode 100644 (file)
index 0000000..0989819
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/members_of11.C
@@ -0,0 +1,26 @@
+// PR c++/124646
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+struct A { int a; };
+struct B { int b; };
+
+consteval auto nsdms(std::meta::info i) {
+  return define_static_array(nonstatic_data_members_of(i, std::meta::access_context::unchecked()));
+}
+
+consteval void print_nsdms(std::meta::info i) {
+    auto msg = std::string("members of ") + display_string_of(i) + " are:";
+    for (auto mem : nsdms(i)) {
+        msg += " ";
+        msg += display_string_of(mem);
+    }
+    __builtin_constexpr_diag(0, "", msg); // { dg-message "members of B are: B::b" }
+}
+
+consteval {
+    print_nsdms(^^A);
+    print_nsdms(^^B);
+}

diff --git a/gcc/testsuite/g++.dg/reflect/members_of12.C b/gcc/testsuite/g++.dg/reflect/members_of12.C
new file mode 100644 (file)
index 0000000..198ef33
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/members_of12.C
@@ -0,0 +1,37 @@
+// PR c++/124645
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+namespace reg
+{
+template <auto namespace_info>
+struct derived_type_registry
+{
+  static consteval auto
+      reflected_types(std::meta::info scope = namespace_info)
+  {
+    std::vector<std::meta::info> infos;
+
+    for(auto member : members_of(scope, std::meta::access_context::unchecked()))
+    {
+      if (member == std::meta::info{}) continue;
+    }
+
+    return infos;
+  }
+};
+}
+
+namespace ns1 {
+    struct test {};
+}
+
+namespace ns2 {
+}
+
+static_assert(reg::derived_type_registry<^^ns1>::reflected_types().empty());
+static_assert(reg::derived_type_registry<^^ns1>::reflected_types().size() == 0);
+static_assert(reg::derived_type_registry<^^ns2>::reflected_types().empty());
+static_assert(reg::derived_type_registry<^^ns2>::reflected_types().size() == 0);