https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107532
Bug ID: 107532
Summary: [13 Regression] -Werror=dangling-reference false
positives in libcamera-0.0.1
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
CC: mpolacek at gcc dot gnu.org
Target Milestone: ---
libcamera-0.0.1 and a few other projects (like cvise) fail to compile due to
-Werror on -Werror=dangling-reference.
I think those are false positives related to value-like types that pass
references through.
Extracted example from libcamera:
// $ cat a.cpp.cpp
struct Plane { unsigned int bytesused; };
// Passes a reference through. Does not change lifetime.
template <typename Inner>
struct Ref {
const Inner & i_;
Ref(const Inner & i) : i_(i) {}
const Inner & inner() { return i_; }
};
struct FrameMetadata {
Ref<const Plane> planes() const { return p_; }
Plane p_;
};
void bar(const Plane & meta);
void foo(const FrameMetadata & fm)
{
const Plane & meta = fm.planes().inner();
bar(meta);
}
$ g++-13.0.0 -c -Wall -Werror=dangling-reference a.cpp
a.cpp: In function 'void foo(const FrameMetadata&)':
a.cpp:20:19: error: possibly dangling reference to a temporary
[-Werror=dangling-reference]
20 | const Plane & meta = fm.planes().inner();
| ^~~~
a.cpp:20:43: note: the temporary was destroyed at the end of the full
expression '(& fm)->FrameMetadata::planes().Ref<const Plane>::inner()'
20 | const Plane & meta = fm.planes().inner();
| ~~~~~~~~~~~~~~~~~^~
cc1plus: some warnings being treated as errors
This gcc version is this week's gcc-13 snapshot with
https://gcc.gnu.org/PR107488 applied on top.
