clang-tidy and scan-build warn about a potential memory leak in this code:
#include <tuple>
#include <memory>
int main()
{
auto lambda = [tuple = std::make_tuple(std::make_unique<int>(42))] {};
}
$ clang-tidy main.cpp -checks="clang*"
1 warning generated.
/foo/main.cpp:7:1: warning: Potential leak of memory pointed to by field '_M_head_impl' [clang-analyzer-cplusplus.NewDeleteLeaks]
}
^
/foo/main.cpp:6:44: note: Calling 'make_unique<int, int>'
auto lambda = [tuple = std::make_tuple(std::make_unique<int>(42))] {};
^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/bits/unique_ptr.h:962:30: note: Memory is allocated
{ return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...)); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/foo/main.cpp:6:44: note: Returned allocated memory
auto lambda = [tuple = std::make_tuple(std::make_unique<int>(42))] {};
^~~~~~~~~~~~~~~~~~~~~~~~~
/foo/main.cpp:7:1: note: Potential leak of memory pointed to by field '_M_head_impl'
}
^
Is there anything I do not see, or is it a false positive?
Environment: clang 13.0.0, gcc 11.3.1.
Compile commands:
[
{
"directory": "/foo",
"command": "/usr/bin/g++ -std=c++17 /foo/main.cpp",
"file": "/foo/main.cpp"
}
]
Notes: the issue is reproducible with -std=c++17 and -std=c++20, but not with -std=c++14.
An unsolved bug in clang-tidy: https://github.com/llvm/llvm-project/issues/55219
It doesn't have anything to do with tuples or smart pointers as seen in the simplified reproduction in this comment.