https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102263
Bug ID: 102263
Summary: Requesting enhanced warning on returning
pointer/reference to local
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: barry.revzin at gmail dot com
Target Milestone: ---
gcc (and clang) both warn on both of these functions:
int* a() {
int i = 0;
return &i;
}
int& b() {
int i = 0;
return i;
}
Which is great. Both of these functions are bad. However, add an extra layer:
struct Ptr { int* p; };
struct Ref { int& r; };
Ptr c() {
int i = 0;
return Ptr{.p=&i};
}
Ref d() {
int i = 0;
return Ref{.r=i};
}
And now gcc (nor clang) warn on either of these two functions. But 'c' and 'd'
are just as much returning a pointer/reference to a local variable as 'a' and
'b' are, and it would be extremely helpful to warn on these cases.
More motivating example from C++20 would be something like this (which came up
in discussion of P2415):
std::vector<int> get_ints();
auto doubled_ints() {
auto ints = get_ints();
return ints | std::views::transform([](int i){ return i * 2; });
}
This is returning an object that has a member that has a member that has a
pointer to a local variable. Which is bad, this dangles! It would be super cool
if such a function got a warning slapped onto it.
