[Bug c++/49651] [C++0x] nested lambdas and -O3 produced incorrect integer variable increments

[pedro.larroy at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49651

--- Comment #1 from Pedro Larroy <pedro.larroy at gmail dot com> 2011-07-05 
20:30:13 UTC ---
I think I'm able to reproduce with the following:

the output spotted is:


run.for_each.a: 20633
run.a: 20634
1 for_each.a: 20631
1 for_each.a: 20632

Compiled with:
g++ -Wall -std=c++0x -O3 -o test test.cc

Code follows:

#include <iostream>
#include <string>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <stdexcept>
#include <stdint.h>
#include <algorithm>
#include <stdint.h>

typedef uint32_t u32;
using namespace std;
vector<u32> g;
void f(u32 a, u32 b) 
{   
    g.push_back(b);
}

int main(int argc, char *argv[])
{
    u32 a = 0;
    vector<int> vi;
    vi.push_back(0);
    vi.push_back(1);
    vi.push_back(2);
    vi.push_back(3);
    vi.push_back(4);


    vector<int> vo;
    vo.push_back(5);
    vo.push_back(5);

    vector<int> ve;
    ve.push_back(5);


    vector<int> v3;
    vector<int> v4;
    vector<int> v5;
    vector<int> v6;
    vector<int> v7;

    f(32, a++);
    cout << "bmain.a: " << a << endl;

    f(32, a++);
    cout << "bmain.a: " << a << endl;


    auto run = [&](int& i) {
        // inside this lambda &a is not the same as the &a in the first line
        v3.push_back(i);
        v4.push_back(i);
        v5.push_back(i);
        v6.push_back(i);
        v7.push_back(i);
        f(32, a++);
        cout << "run.a: " << a << endl;

        v3.push_back(i);
        v4.push_back(i);
        v5.push_back(i);
        v6.push_back(i);
        v7.push_back(i);
        f(32, a++);
        cout << "run.a: " << a << endl;



        for_each(ve.begin(), ve.end(), [&](int& xi) {
            v7.push_back(xi);
            f(32, a++);
            cout << "run.for_each.a: " << a << endl;

        });

        f(32, a++);
        cout << "run.a: " << a << endl;
    };

    f(32, a++);
    cout << "main.a: " << a << endl;

    while(true) {
    for_each(vi.begin(), vi.end(), [&](int& xi) {
        f(32, a++);
        cout << "1 for_each.a: " << a << endl;


        for_each(vo.begin(), vo.end(), run);

        f(32, a++);
        cout << "1 for_each.a: " << a << endl;


        for_each(ve.begin(), ve.end(), run);

        f(32, a++);
        cout << "1 for_each.a: " << a << endl;


    });
    }
    cout << "main.a: " << a << endl;
}