https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90740
Bug ID: 90740
Summary: regression - Incorrect warning (is used uninitialized
in this function)
Product: gcc
Version: 9.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: v at vsamko dot com
Target Milestone: ---
We are not "using" `buf` there. We are passing it by reference, which is a
valid code and it shouldn't raise any warnings (for example, it can be a buffer
pointer that we pass as a destination to memcpy, and it does not need to be
initialised).
If we replace "int SIZE = 100" with "constexpr int SIZE = 100" then the warning
goes away, which doesn't make any sense.
g++ 7 and 8 don't show this warning on this code.
Also, why does the warning refers to the variable as "<anonymous>" when it
clearly has a name?
=========
template<typename T, typename... U>
void bar(T t, U... u) {
t(u...);
}
template<typename T>
void doit(T) {}
int SIZE = 100;
template<typename ...Vs>
void read(Vs & ...out) {
char buf[SIZE];
bar([&buf, &out...](auto&... column) { (doit(column), ...); }, out...);
}
int main() {
int x1;
read(x1);
}
=========
source>: In lambda function:
<source>:14:9: warning: '<anonymous>' is used uninitialized in this function
[-Wuninitialized]
14 | bar([&buf, &out...](auto&... column) { (doit(column), ...); },
out...);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:13:10: note: '<anonymous>' was declared here
13 | char buf[SIZE];
| ^~~
Compiler returned: 0
