https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78391
Bug ID: 78391
Summary: g++ (any version) at O0 (for O1, O2, O3 is ok) doesn't
warn when class members are used uninitialized.
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lucanus81 at gmail dot com
Target Milestone: ---
Created attachment 40063
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40063&action=edit
Minimal testcase that shows the (possible) problem.
It seems like g++ (any version) doesn't warn when class members are
uninitialized when no optimization is enabled (and at -O0). For -O1, -O2, -O3
we correctly get a warning (On the contrary, clang, any version, reports a
warning at any optimization level).
struct data { int x=w; int w=10; };
int main() {
data d;
return d.x;
}
g++ ub.cpp -Wall -Wextra -std=gnu++1z -O0
=> no warning
g++ ub.cpp -Wall -Wextra -std=gnu++1z -O1
=>
ub.cpp: In function 'int main()':
ub.cpp:4:10: warning: 'd.data::w' is used uninitialized in this function
[-Wuninitialized]
data d;
for -O2, -O3 we get exactly the same warning.
