On 1/5/25 3:01 PM, Simon Martin wrote:
We currently fail with a checking assert upon the following valid code when using -fno-elide-constructors=== cut here === struct d { ~d(); }; d &b(); struct f { [[__no_unique_address__]] d e; }; struct h : f { h() : f{b()} {} } i; === cut here === The problem is that split_nonconstant_init_1 detects that it cannot elide the copy constructor due to __no_unique_address__ but does not clear TARGET_EXPR_ELIDING_P, and due to -fno-elide-constructors, we trip on a checking assert in cp_gimplify_expr. This patch fixes this by making sure that we clear TARGET_EXPR_ELIDING_P if we determine that we have to keep the copy constructor due to __no_unique_address__. An alternative would be to just check for elide_constructors in that assert, but I think it'd lose most of its value if we did so. Successfully tested on x86_64-pc-linux-gnu.
OK.
PR c++/118199 gcc/cp/ChangeLog: * typeck2.cc (split_nonconstant_init_1): Clear TARGET_EXPR_ELIDING_P if we need to use a copy constructor because of __no_unique_address__. gcc/testsuite/ChangeLog: * g++.dg/init/no-elide3.C: New test. --- gcc/cp/typeck2.cc | 5 +++++ gcc/testsuite/g++.dg/init/no-elide3.C | 12 ++++++++++++ 2 files changed, 17 insertions(+) create mode 100644 gcc/testsuite/g++.dg/init/no-elide3.C diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc index 381f198d0fe..f50c5f767bb 100644 --- a/gcc/cp/typeck2.cc +++ b/gcc/cp/typeck2.cc @@ -655,6 +655,11 @@ split_nonconstant_init_1 (tree dest, tree init, bool last, && make_safe_copy_elision (sub, value)) goto build_init;+ if (TREE_CODE (value) == TARGET_EXPR)+ /* We have to add this constructor, so we will not + elide. */ + TARGET_EXPR_ELIDING_P (value) = false; + tree name = (DECL_FIELD_IS_BASE (field_index) ? base_ctor_identifier : complete_ctor_identifier); diff --git a/gcc/testsuite/g++.dg/init/no-elide3.C b/gcc/testsuite/g++.dg/init/no-elide3.C new file mode 100644 index 00000000000..659eb19bc95 --- /dev/null +++ b/gcc/testsuite/g++.dg/init/no-elide3.C @@ -0,0 +1,12 @@ +// PR c++/118199 +// { dg-do "compile" { target c++11 } } +// { dg-options "-fno-elide-constructors" } + +struct d { ~d(); }; +d &b(); +struct f { + [[__no_unique_address__]] d e; +}; +struct h : f { + h() : f{b()} {} +} i;
