In this testcase, cxx_eval_store_expression got confused trying to build up
CONSTRUCTORs for initializing a subobject because the subobject is a member
of an empty base. In C++14 mode and below we don't build FIELD_DECLs for
empty bases, so the CONSTRUCTOR skipped the empty base, and treated the
member as a member of the derived class, which breaks.
Fixed by recognizing this situation and giving up on trying to build a
CONSTRUCTOR for the inner target at that point; since it doesn't have any
data, we don't need to actually store anything.
Tested x86_64-pc-linux-gnu, applying to trunk.
gcc/cp/ChangeLog:
PR c++/98463
* constexpr.c (get_or_insert_ctor_field): Add check.
(cxx_eval_store_expression): Handle discontinuity of refs.
gcc/testsuite/ChangeLog:
PR c++/98463
* g++.dg/cpp2a/no_unique_address8.C: New test.
---
gcc/cp/constexpr.c | 18 ++++++++++++++++--
.../g++.dg/cpp2a/no_unique_address8.C | 11 +++++++++++
2 files changed, 27 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/no_unique_address8.C
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index b787919942b..c1217535761 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -3474,7 +3474,9 @@ get_or_insert_ctor_field (tree ctor, tree index, int
pos_hint = -1)
}
else
{
- gcc_assert (TREE_CODE (index) == FIELD_DECL);
+ gcc_assert (TREE_CODE (index) == FIELD_DECL
+ && (same_type_ignoring_top_level_qualifiers_p
+ (DECL_CONTEXT (index), TREE_TYPE (ctor))));
/* We must keep the CONSTRUCTOR's ELTS in FIELD order.
Usually we meet initializers in that order, but it is
@@ -5289,6 +5291,18 @@ cxx_eval_store_expression (const constexpr_ctx *ctx,
tree t,
type = refs->pop();
tree index = refs->pop();
+ if (TREE_CODE (index) == FIELD_DECL
+ && !(same_type_ignoring_top_level_qualifiers_p
+ (DECL_CONTEXT (index), TREE_TYPE (*valp))))
+ {
+ /* INDEX isn't a member of *valp. This can happen if it's a member
+ of an empty base which isn't represented with a FIELD_DECL. Stop
+ trying to build a CONSTRUCTOR for the inner target; we'll notice
+ this disconnect again below and just return init. */
+ gcc_assert (is_empty_class (DECL_CONTEXT (index)));
+ break;
+ }
+
if (code == UNION_TYPE && CONSTRUCTOR_NELTS (*valp)
&& CONSTRUCTOR_ELT (*valp, 0)->index != index)
{
diff --git a/gcc/testsuite/g++.dg/cpp2a/no_unique_address8.C
b/gcc/testsuite/g++.dg/cpp2a/no_unique_address8.C
new file mode 100644
index 00000000000..8b63ca37bab
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/no_unique_address8.C
@@ -0,0 +1,11 @@
+// PR c++/98463
+// { dg-do compile { target c++11 } }
+
+template <typename T> struct A { constexpr A () : a() {} [[no_unique_address]]
T a; };
+template <unsigned long, typename...> struct B;
+template <unsigned long T, typename U, typename... V>
+struct B<T, U, V...> : B<1, V...>, A<U> {};
+template <unsigned long T, typename U> struct B<T, U> : A<U> {};
+template <typename... h> struct C : B<0, h...> {};
+struct D {};
+struct E { C<int, D> k; virtual ~E (); } a;
base-commit: 10c83fb7131779ee27fbaa9091065ca6cfedc0c5
--
2.27.0
