[Bug analyzer/115313] False positive -fanalyzer use of uninitialized value due to std::string's default constructor

[llvm at rifkin dot dev via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115313

--- Comment #1 from Jeremy R. <llvm at rifkin dot dev> ---
Reduced:

#include <string>

std::string foo() {
    std::string str;
    return str;
}


<source>: In function 'std::string foo()':
<source>:4:17: warning: use of uninitialized value '<unknown>' [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
    4 |     std::string str;
      |                 ^~~
  'std::string foo()': events 1-3
    |
    |    3 | std::string foo() {
    |      | ^~~
    |      | |
    |      | (1) region created on stack here
    |      | (2) capacity: 8 bytes
    |    4 |     std::string str;
    |      |                 ~~~
    |      |                 |
    |      |                 (3) use of uninitialized value '<unknown>' here
    |