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| author | Jason Merrill <jason@redhat.com> | 2021-11-11 22:03:53 -0500 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2021-11-15 02:49:51 -0500 |
| commit | bd95d75f3412e1a7debab7c6c602ba409f274eb5 (patch) | |
| tree | 863b4a8caeabd36dc1542a590976dd45fedc453b /gcc/cp | |
| parent | 4df7f8c79835d56928f51f9e674d326300936e8e (diff) | |
| download | gcc-bd95d75f3412e1a7debab7c6c602ba409f274eb5.zip gcc-bd95d75f3412e1a7debab7c6c602ba409f274eb5.tar.gz gcc-bd95d75f3412e1a7debab7c6c602ba409f274eb5.tar.bz2 | |
c++: c++20 constexpr default ctor and array init
The implicit constexpr patch revealed that marking the constructor in the
PR70690 testcase as constexpr made the bug reappear, because build_vec_init
assumed that a constexpr default constructor initialized the whole object,
so it was equivalent to value-initialization. But this is no longer true in
C++20.
PR c++/70690
gcc/cp/ChangeLog:
* init.c (build_vec_init): Check default_init_uninitialized_part in
C++20.
gcc/testsuite/ChangeLog:
* g++.dg/init/array41a.C: New test.
Diffstat (limited to 'gcc/cp')
| -rw-r--r-- | gcc/cp/init.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/gcc/cp/init.c b/gcc/cp/init.c index 771a19b..3ba2e3b 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -4470,11 +4470,14 @@ build_vec_init (tree base, tree maxindex, tree init, We do need to keep going if we're copying an array. */ - if (try_const && !init) + if (try_const && !init + && (cxx_dialect < cxx20 + || !default_init_uninitialized_part (inner_elt_type))) /* With a constexpr default constructor, which we checked for when setting try_const above, default-initialization is equivalent to value-initialization, and build_value_init gives us something more - friendly to maybe_constant_init. */ + friendly to maybe_constant_init. Except in C++20 and up a constexpr + constructor need not initialize all the members. */ explicit_value_init_p = true; if (from_array || ((type_build_ctor_call (type) || init || explicit_value_init_p) |