https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87665
Bug ID: 87665
Summary: gcc HEAD (svn: 265340) breaks elements on resize
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: linux at obiwahn dot org
Target Milestone: ---
» cat test.cpp
#include <iostream>
#include <cstdlib>
#include <vector>
#include <memory>
#include <functional>
int main()
{
using my_pair = std::pair<std::unique_ptr<int>, double*>;
std::vector<my_pair> vec;
for (int i = 0; i < 17; ++i) {
std::unique_ptr<int> p(new int(i));
vec.emplace_back(std::move(p), nullptr);
std::cerr << "capacity: " << vec.capacity() << " size: " << vec.size() <<
std::endl;
for (size_t i = 0, count = vec.size(); i < count; ++i) {
std::cerr << " " << i << "-" << (vec[i].first == nullptr ? "fail" :
"ok");
}
std::cerr << std::endl;
}
}
» g++-head test.cpp -O3 -Wall -Wshadow -std=c++14 && ./a.out
test.cpp: In function ‘int main()’:
test.cpp:16:17: warning: declaration of ‘i’ shadows a previous local [-Wshadow]
16 | for (size_t i = 0, count = vec.size(); i < count; ++i) {
| ^
test.cpp:12:12: note: shadowed declaration is here
12 | for (int i = 0; i < 17; ++i) {
| ^
capacity: 1 size: 1
0-ok
capacity: 2 size: 2
0-ok 1-ok
capacity: 4 size: 3
0-ok 1-ok 2-ok
capacity: 4 size: 4
0-ok 1-ok 2-ok 3-ok
capacity: 8 size: 5
0-fail 1-fail 2-fail 3-fail 4-ok
capacity: 8 size: 6
0-fail 1-fail 2-fail 3-fail 4-ok 5-ok
capacity: 8 size: 7
0-fail 1-fail 2-fail 3-fail 4-ok 5-ok 6-ok
capacity: 8 size: 8
0-fail 1-fail 2-fail 3-fail 4-ok 5-ok 6-ok 7-ok
capacity: 16 size: 9
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok
capacity: 16 size: 10
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok
capacity: 16 size: 11
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok 10-ok
capacity: 16 size: 12
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok 10-ok 11-ok
capacity: 16 size: 13
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok 10-ok 11-ok
12-ok
capacity: 16 size: 14
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok 10-ok 11-ok
12-ok 13-ok
capacity: 16 size: 15
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok 10-ok 11-ok
12-ok 13-ok 14-ok
capacity: 16 size: 16
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-ok 9-ok 10-ok 11-ok
12-ok 13-ok 14-ok 15-ok
capacity: 32 size: 17
0-fail 1-fail 2-fail 3-fail 4-fail 5-fail 6-fail 7-fail 8-fail 9-fail 10-fail
11-fail 12-fail 13-fail 14-fail 15-fail 16-ok
The code compiles and works fine with recent clang. If the shadowed variable is
changed to something else or the double* member is replaced by something else
the code works as expected.
The behavior was originally found by Vasiliy Nabatchikov on gcc 8.2 using
`typedef std::function<uint32_t(uint32_t)> f_t; typedef
std::pair<std::unique_ptr<int>, f_t*> term_iterator_t1` as pair type.
gcc was build with `--disable-multilib` and custom suffix and prefix on Debian
stable and sid.
