https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117259
Bug ID: 117259
Summary: warning: 'j.6' may be used uninitialized
[-Wmaybe-unitialized] with -fsanitize=undefined
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: m.gcc.gnu.org at alias dot viem.se
Target Milestone: ---
/*
Accessing dynamically initialized array of global member function pointer using
a non const index variable gives false and ill-formed warning if compiling with
-fsanitize=undefined (bounds) and -O1.
Warning disappears if either:
1. changing to static initialization by removing user defined B constructor
2. using const index variable (with same value)
3. using -O0
4. using no -fsanitize or something else than -fsanitize=undefined,
-fsanitize=bounds, or, -fsanitize=bounds-strict
5. using gcc 10 or older
$ gcc -fsanitize=undefined -Wmaybe-uninitialized -O1 -c bug.cpp
bug.cpp: In member function 'void A::f()':
bug.cpp:48:15: warning: 'j.6' may be used uninitialized [-Wmaybe-uninitialized]
48 | (this->*bs[j].g)(); // warning: 'j.6' may be used uninitialized
| ~~~~^
bug.cpp:48:15: note: 'j.6' was declared here
48 | (this->*bs[j].g)(); // warning: 'j.6' may be used uninitialized
| ~~~~^
gcc 11.1 up to gcc 14.2 show warning.
gcc 12.1 up to gcc 14.2 also show note.
*/
struct A {
struct B {
void (A::*g) ();
B(void (A::*func)()) : g(func) {};
};
static const B bs[1];
void f();
void h(){}
};
const A::B A::bs[1] = {{&A::h}};
void A::f() {
(this->*bs[0].g)(); // no warning
const unsigned i = 0;
(this->*bs[i].g)(); // no warning
unsigned j = 0;
(this->*bs[j].g)(); // warning: 'j.6' may be used uninitialized
}
