The delete-memcpy-with-non-trivial-types patch exposed many instances
of this problem:
src/gdb/btrace.h: In function ‘btrace_insn_s* VEC_btrace_insn_s_quick_insert(VEC_btrace_insn_s*, unsigned int, const btrace_insn_s*, const char*, unsigned int)’:
src/gdb/common/vec.h:948:62: error: use of deleted function ‘void* memmove(T*, const U*, size_t) [with T = btrace_insn; U = btrace_insn; <template-parameter-1-3> = void; size_t = long unsigned int]’
memmove (slot_ + 1, slot_, (vec_->num++ - ix_) * sizeof (T)); \
^
src/gdb/common/vec.h:436:1: note: in expansion of macro ‘DEF_VEC_FUNC_O’
DEF_VEC_FUNC_O(T) \
^
src/gdb/btrace.h:84:1: note: in expansion of macro ‘DEF_VEC_O’
DEF_VEC_O (btrace_insn_s);
^
[...]
src/gdb/common/vec.h:1060:31: error: use of deleted function ‘void* memcpy(T*, const U*, size_t) [with T = btrace_insn; U = btrace_insn; <template-parameter-1-3> = void; size_t = long unsigned int]’
sizeof (T) * vec2_->num); \
^
src/gdb/common/vec.h:437:1: note: in expansion of macro ‘DEF_VEC_ALLOC_FUNC_O’
DEF_VEC_ALLOC_FUNC_O(T) \
^
src/gdb/btrace.h:84:1: note: in expansion of macro ‘DEF_VEC_O’
DEF_VEC_O (btrace_insn_s);
^
So, VECs (given it's C roots) rely on memcpy/memcpy of VEC elements to
be well defined, in order to grow/reallocate its internal elements
array. This means that we can only put trivially copyable types in
VECs. E.g., if a type requires using a custom copy/move ctor to
relocate, then we can't put it in a VEC (so we use std::vector
instead). But, as shown above, we're violating that requirement.
btrace_insn is currently not trivially copyable, because it contains
an enum_flags field, and that is itself not trivially copyable. This
patch corrects that, by simply removing the user-provided copy
constructor and assignment operator. The compiler-generated versions
work just fine.
Note that std::vector relies on std::is_trivially_copyable too to know
whether it can reallocate its elements with memcpy/memmove instead of
having to call copy/move ctors and dtors, so if we have types in
std::vectors that weren't trivially copyable because of enum_flags,
this will make such vectors more efficient.
gdb/ChangeLog:
2017-04-25 Pedro Alves <palves@redhat.com>
* common/enum-flags.h (enum_flags): Don't implement copy ctor and
assignment operator.
23bcc18f47