https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116360
Bug ID: 116360
Summary: GCC gives false positive dangling reference for static
local variable
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jlame646 at gmail dot com
Target Milestone: ---
The following program produces false positive with static variable.
https://godbolt.org/z/P1G8YMvfK
```
# include <iostream>
std::string create_default_x() noexcept
{
std::string default_x = "hello world";
return default_x;
}
std::string const& get_x(std::string const& force_x = "") noexcept;
int main()
{
std::string const& x = get_x();
std::cout << x << std::endl;
return 0;
}
std::string const& get_x(std::string const& force_x) noexcept
{
static std::string x = (force_x.empty() ? create_default_x() :
std::string());
if(!force_x.empty())
x = force_x;
return x;
}
```
GCC says:
```
warning: possibly dangling reference to a temporary [-Wdangling-reference]
13 | std::string const& x = get_x();
| ^
<source>:13:33: note: the temporary was destroyed at the end of the full
expression 'get_x(std::__cxx11::basic_string<char>(((const char*)""),
std::allocator<char>()))'
13 | std::string const& x = get_x();
| ~~~~~^~
ASM generation compiler returned: 0
<source>: In function 'int main()':
<source>:13:24: warning: possibly dangling reference to a temporary
[-Wdangling-reference]
13 | std::string const& x = get_x();
| ^
<source>:13:33: note: the temporary was destroyed at the end of the full
expression 'get_x(std::__cxx11::basic_string<char>(((const char*)""),
std::allocator<char>()))'
13 | std::string const& x = get_x();
```
We can use `-Wno-dangling-reference` to supress this.
