Tested x86_64-pc-linux-gnu, applying to trunk. -- 8< --
Here, because we don't build a CONSTRUCTOR for an empty base, we were wrongly marking the Foo CONSTRUCTOR as complete after initializing the Empty member. Fixed by checking empty_base here as well. PR c++/112439 gcc/cp/ChangeLog: * constexpr.cc (cxx_eval_store_expression): Check empty_base before marking a CONSTRUCTOR readonly. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/no_unique_address15.C: New test. --- gcc/cp/constexpr.cc | 1 + .../g++.dg/cpp2a/no_unique_address15.C | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+) create mode 100644 gcc/testsuite/g++.dg/cpp2a/no_unique_address15.C diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index 6350fe15408..2ebb1470dd5 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -6694,6 +6694,7 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, object. Make a note of this fact by marking the CONSTRUCTOR TREE_READONLY. */ if (TREE_CODE (t) == INIT_EXPR + && !empty_base && TREE_CODE (*valp) == CONSTRUCTOR && TYPE_READONLY (type)) { diff --git a/gcc/testsuite/g++.dg/cpp2a/no_unique_address15.C b/gcc/testsuite/g++.dg/cpp2a/no_unique_address15.C new file mode 100644 index 00000000000..3e7cf0838e1 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/no_unique_address15.C @@ -0,0 +1,19 @@ +// PR c++/112439 +// { dg-do compile { target c++14 } } + +struct Empty {}; + +class Foo { +public: + constexpr Foo(int x, Empty y, int z) : a(x), b(y) + { + c = z; + } + +private: + int a{}; + [[no_unique_address]] Empty b{}; + [[no_unique_address]] int c{}; +}; + +constexpr Foo r{1, {}, 3}; base-commit: e0701f8f7b6dcddb299eb5345e510cf9ea419150 prerequisite-patch-id: 710b09d2d596e61c5634974a1dca99c51506d903 -- 2.39.3