https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90598
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The problem is that by the time finish_decltype_type is called, the destructor
call is already folded into a TARGET_EXPR <D.2335, {}> = {CLOBBER};
The following untested patch fixes it for me:
2019-05-23 Jakub Jelinek <ja...@redhat.com>
PR c++/90598
* call.c (build_trivial_dtor_call): Wrap MODIFY_EXPR for
-flifetime-dse into void_type_node NOP_EXPR.
* g++.dg/cpp0x/pr90598.C: New test.
--- gcc/cp/call.c.jj 2019-05-23 12:57:16.658493722 +0200
+++ gcc/cp/call.c 2019-05-23 18:37:09.570874611 +0200
@@ -7995,8 +7995,8 @@ build_trivial_dtor_call (tree instance)
/* A trivial destructor should still clobber the object. */
tree clobber = build_clobber (TREE_TYPE (instance));
- return build2 (MODIFY_EXPR, void_type_node,
- instance, clobber);
+ return build1 (NOP_EXPR, void_type_node,
+ build2 (MODIFY_EXPR, void_type_node, instance, clobber));
}
/* Subroutine of the various build_*_call functions. Overload resolution
--- gcc/testsuite/g++.dg/cpp0x/pr90598.C.jj 2019-05-23 18:39:37.034464509
+0200
+++ gcc/testsuite/g++.dg/cpp0x/pr90598.C 2019-05-23 18:39:05.471980348
+0200
@@ -0,0 +1,8 @@
+// PR c++/90598
+// { dg-do compile { target c++11 } }
+
+struct A {};
+using B = decltype(A ().~A ());
+template <typename T> struct C;
+template <> struct C<void> {};
+C<B> t;
