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c++: aggregate base and TARGET_EXPR_ELIDING_P [PR108559]

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We also need to split up a CONSTRUCTOR in cp_genericize_init if we need to
add extra copy constructor calls to deal with CWG2403.

	PR c++/108559

gcc/cp/ChangeLog:

	* cp-gimplify.cc (any_non_eliding_target_exprs): New.
	(cp_genericize_init): Check it.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/aggr-base13.C: New test.
This commit is contained in:
Jason Merrill 2023-01-30 18:18:54 -05:00
parent a9fbc6687f
commit b533084d75
2 changed files with 38 additions and 3 deletions
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22
gcc/cp/cp-gimplify.cc
View file

@ -893,6 +893,21 @@ omp_cxx_notice_variable (struct cp_genericize_omp_taskreg *omp_ctx, tree decl)
}
}
/* True if any of the element initializers in CTOR are TARGET_EXPRs that are
not expected to elide, e.g. because unsafe_copy_elision_p is true. */
static bool
any_non_eliding_target_exprs (tree ctor)
{
for (const constructor_elt &e : *CONSTRUCTOR_ELTS (ctor))
{
if (TREE_CODE (e.value) == TARGET_EXPR
&& !TARGET_EXPR_ELIDING_P (e.value))
return true;
}
return false;
}
/* If we might need to clean up a partially constructed object, break down the
CONSTRUCTOR with split_nonconstant_init. Also expand VEC_INIT_EXPR at this
point. If initializing TO with FROM is non-trivial, overwrite *REPLACE with
@ -904,10 +919,11 @@ cp_genericize_init (tree *replace, tree from, tree to)
tree init = NULL_TREE;
if (TREE_CODE (from) == VEC_INIT_EXPR)
init = expand_vec_init_expr (to, from, tf_warning_or_error);
else if (flag_exceptions
&& TREE_CODE (from) == CONSTRUCTOR
else if (TREE_CODE (from) == CONSTRUCTOR
&& TREE_SIDE_EFFECTS (from)
&& TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (from)))
&& ((flag_exceptions
&& TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (from)))
|| any_non_eliding_target_exprs (from)))
{
to = cp_stabilize_reference (to);
replace_placeholders (from, to);

19
gcc/testsuite/g++.dg/cpp1z/aggr-base13.C Normal file
View file

@ -0,0 +1,19 @@
// PR c++/108559
// { dg-do compile { target c++17 } }
struct A {
int g = 0;
A() {}
A(const A&) {}
};
struct B : A {};
A u() { return A{}; }
int bug() { return B{u()}.g; }
int main() {
return 0;
}