https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109515
Bug ID: 109515
Summary: Diagnostic request: warning on out-of-order structured
bindings names
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: ---
Consider this example:
struct div_t {
int quot;
int rem;
};
auto div(int, int) -> div_t;
int main() {
auto [rem, quot] = div(1, 2);
return quot;
}
I'm using structured bindings, but div_t's members are in the order quot then
rem, but I accidentally typed rem then quot. This is a bug! Currently, nobody
warns here though.
At the very least, if I'm:
(a) using a name in a structured binding,
(b) where we fall into the 3rd case of structured bindings (struct, not
array/tuple),
(c) the name I'm using is the name of one of the members of the type, and
(d) the structured binding is in the wrong place
I think that's a situation where a warning would have a low false-positive
rate, could be a useful -Wall (or at least -Wextra) kind of warning.
There's a more expansive potential diagnostic, if I used names that weren't
names of members at all, but I think that sort of warning would have to be
opt-in.
