Compilation error of fu2::unique_function having a capture [ std::vector< std::vector < std::unique_ptr<int> > > ]

[scherno2000]

@Naios

The code attached does not compile. This is probably because of the two dimensional vector of uncopyable objects (unique_ptrs)

By uncommenting the dummy variable at the line 31 in the capture the code compiles and runs as expected

---

Commit Hash

Latest commit e30dbbe on 13 Apr

Expected Behavior

To be compilable, and functioning

Actual Behavior

It doesn't compile, error message:

D:\mingw-w64\x86_64-7.2.0-posix-seh-rt_v5-rev0\mingw64\lib\gcc\x86_64-w64-mingw32\7.2.0\include\c++\bits\stl_construct.h|75|error: use of deleted function 'std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = int; _Dp = std::default_delete]'|

Steps to Reproduce

Please use the example code given in the attachment

main.zip

Your Environment

• OS: { Windows } same behavior on Linux
• Compiler and version: { MinGW w64, GCC version 7.2, but the same behavior on Linux
• Standard library - default

[Naios]

Thanks for reporting this issue.

I could narrow the test case down to:

static fu2::unique_function<void()> issue_14_create() {
  // remove the commented dummy capture to be compilable
  fu2::unique_function<void()> func =
      [
        i = std::vector<std::vector<std::unique_ptr<int>>>{}
        // ,dummy = std::unique_ptr<int>()
      ]() {
        // ...
      };

  return std::move(func);
}

// https://github.com/Naios/function2/issues/14
TEST(regression_tests, issue_14) {
  issue_14_create()();
}

I'll investigate into this.

[scherno2000]

1) I discovered that is not necessary a double dimension vector

static fu2::unique_function<void()> issue_14_create() {
  // remove the commented dummy capture to be compilable
  fu2::unique_function<void()> func =
      [
        i = std::vector<std::unique_ptr<int>>{}
        // ,dummy = std::unique_ptr<int>()
      ]() {
        // ...
      };

  return std::move(func);
}

2) I found a workaround by encapsulating the vector inside a struct

struct vector_wrapper
{
    std::vector<std::unique_ptr<int>> vec;
    vector_wrapper() = default;
    vector_wrapper(vector_wrapper&& v):
        vec(std::move(v.vec))
        {}
};

static fu2::unique_function<void()> issue_14_create() {
  // remove the commented dummy capture to be compilable
  fu2::unique_function<void()> func =
      [
        i = vector_wrapper{}
      ]() {
        // ...
      };

  return std::move(func);
}

[Naios]

Thanks for your bug report. It was fixed due to version v3.1.0.