https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89729
Bug ID: 89729
Summary: [g++ 8] -Wclass-memaccess warning
Product: gcc
Version: 8.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: chantry.xavier at gmail dot com
Target Milestone: ---
Created attachment 45975
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45975&action=edit
test case
There are already many bugs about this one, but since I am not expert on C++, I
would like to have your advice.
g++ -std=gnu++98 -c -Wall memaccess-short.cc
memaccess-short.cc: In function ‘void script_data_init_empty(script_data_t*)’:
memaccess-short.cc:14:61: warning: ‘void* memset(void*, int, size_t)’ clearing
an object of type ‘script_data_t’ {aka ‘struct script_data_t’} with no trivial
copy-assignment; use value-initialization instead [-Wclass-memaccess]
({ (typeof(*(p)) *)memset((p), 0, sizeof(*(p)) * (count)); })
^
memaccess-short.cc:19:5: note: in expansion of macro ‘p_clear’
p_clear(&d2, 1);
^~~~~~~
memaccess-short.cc:4:16: note: ‘script_data_t’ {aka ‘struct script_data_t’}
declared here
typedef struct script_data_t {
^~~~~~~~~~~~~
memaccess-short.cc:20:33: warning: ‘void* memcpy(void*, const void*, size_t)’
writing to an object of type ‘script_data_t’ {aka ‘struct script_data_t’} with
no trivial copy-assignment [-Wclass-memaccess]
memcpy(data, &d2, sizeof(d2));
^
memaccess-short.cc:4:16: note: ‘script_data_t’ {aka ‘struct script_data_t’}
declared here
typedef struct script_data_t {
^~~~~~~~~~~~~
I know this is a mix of C and C++ code so not very clean.
What's the correct way in gnu++98 to do this ?
p_clear is in a C header, but I can either write a variant for C++ (using
ifdef), or maybe even directly replace the p_clear calls from C++ files.
The other bugs mention cast to void * as a workaround, this does seem to work,
even with a simple C cast. Is this also acceptable in my case for both memset
and memcpy ?
