https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111123
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mpolacek at gcc dot gnu.org
Blocks| |24639
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The interesting thing is that enabling the middle-end diagnostic to trigger
shows we emit duplicate diagnostics:
struct Camera {
float clip_area;
float border = 10.f;
[[gnu::noinline]] Camera() : clip_area(border) { }
};
Camera foo()
{
Camera c;
return c;
}
emits
t.C: In constructor 'Camera::Camera()':
t.C:4:44: warning: member 'Camera::border' is used uninitialized
[-Wuninitialized]
4 | [[gnu::noinline]] Camera() : clip_area(border) { }
| ^~~~~~
t.C: In constructor 'Camera::Camera()':
t.C:4:44: warning: '*this.Camera::border' is used uninitialized
[-Wuninitialize]
4 | [[gnu::noinline]] Camera() : clip_area(border) { }
| ^~~~~~
the first is from the C++ FE find_uninit_fields diagnostic which for some
reason doesn't work for the testcase in the description, possibly
the initializer list(?) isn't handled? The early uninit IL is
<bb 2> :
MEM[(struct __as_base &)this_6(D)] ={v} {CLOBBER};
_1 = &this_6(D)->clip_area;
std::allocator<Camera::P2d>::allocator (&D.26049);
_2 = this_6(D)->border;
D.26047[0].x = _2;
_3 = this_6(D)->border;
D.26047[0].y = _3;
D.27007._M_array = &D.26047;
D.27007._M_len = 1;
std::vector<Camera::P2d>::vector (_1, D.27007, &D.26049);
the call to std::allocator<Camera::P2d>::allocator is thought to clobber
*this and thus possibly initialize 'border' here.
I'm testing a middle-end fix here - Marek, can you see whether it's possible
to detect this in the frontend? The middle-end will require optimization.
The duplicate diagnostic might also be interesting to look at, but that
might already be reported separately?
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639
[Bug 24639] [meta-bug] bug to track all Wuninitialized issues
