https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81767
Bug ID: 81767
Summary: Unused variable warning with structured binding
Product: gcc
Version: 7.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: antoshkka at gmail dot com
Target Milestone: ---
The following code produces "warning: unused variable 'ignore'
[-Wunused-variable]":
int main() {
int m[2][2] = {{1,2}, {3, 4}};
int sum = 0;
for (auto& [ignore, value] : m) {
sum += value;
}
return sum - 6;
}
This is not good, as multiple users would like to ignore part of the result and
deal only with the other part.
Seems better to warn only if result of structured binding does not used at all:
for (auto& [ignore, value] : m) { // "warning: structured binding result not
used
sum += 0;
}
Otherwise emit no warning (just like clang does).
