https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126131
Bug ID: 126131
Summary: No way to use designated initializers for anonymous
union warning/error free with -std=gnu++20 or later?
Product: gcc
Version: 16.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: sirl at gcc dot gnu.org
Target Milestone: ---
When compiling this snippet with "g++-16 -std=gnu++20 -Wmissing-braces" there
is always either an error or a warning:
typedef void fctp1(void *);
struct s {
int i;
union {
fctp1 *p_fct1;
struct s *p_s;
};
};
struct s sarr1[] = {
{ .i = 0, { .p_s = nullptr } }
};
struct s sarr2[] = {
{ .i = 0, { .p_fct1 = nullptr } }
};
struct s sarr3[] = {
{ .i = 0, .p_fct1 = nullptr }
};
t.cpp:12:19: error: either all initializer clauses should be designated or none
of them should be
12 | { .i = 0, { .p_s = nullptr } }
| ^
t.cpp:16:19: error: either all initializer clauses should be designated or none
of them should be
16 | { .i = 0, { .p_fct1 = nullptr } }
| ^
t.cpp:21:1: warning: missing braces around initializer for 's::<unnamed union>'
[-Wmissing-braces]
21 | };
| ^
With -std=gnu++17 there was only the braces warning and that was easy to fix by
adding the braces. But with -std=gnu++20 or later there is no longer a way to
get this warning/error free except by not using designated initializers at all.
Is this a bug or does gnu++20 really require this?
