https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93018
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Bar has no user-provided default constructor, so indeed the
value-initialization of Bar is zero-initialization followed by
default-initialization.
But, Foo has user-provided default constructor though, and at the start of such
a constructor the object has indeterminate value, so while zero-initialization
initialized the padding bits before, that is ignored later on. It is the same
thing as if you
memset some automatic object's storage to zero and then invoke a default
constructor there.
You can use -flifetime-dse=1 or -fno-lifetime-dse to disable this behavior, see
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flifetime-dse
