On Wednesday 12 August 2015 15:58:36 Jeffrey Walton wrote:
> The variable that is triggering the uninitialized access is a simple
> flag and I believe it is initialized:
>
> bool g_flag = false;
>
> The C++ object that uses it is in another translation unit, and it has
> a init_pritority attribute.
>
> I think I'm missing a finer detail on the confluence of the C++
> standard intersecting default initialization tricks in the BSS segment
> taken modulo what Valgrind sees (or believes it sees). I *think* it
> also has something to do with the double value initialization
> discussed in
> https://stackoverflow.com/questions/25742863/why-file-scope-static-variables-have-to-be-zero-initialized.
>
> Can someone help me understand what's going on?
It could be the initialzation order of the modules that causes the other
translation unit to have its initializer run before g_flag is initialized. But
g_flag should be initialized automatically by the compiler/linker before any
code is run.
There is another possibility:
bool not_initialized;
bool g_flag = false;
int main(void) {
g_flag = not_initialized;
if(g_flag)
printf("true");
else
printf("false");
return 0;
}
The 'uninitializeness' is copied when memory is copied. Have you checked that
this is not what is going on?
/isj
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