[Bug c++/108165] New: -Wdangling-reference false positive

[romain.geissler at amadeus dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108165

            Bug ID: 108165
           Summary: -Wdangling-reference false positive
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: romain.geissler at amadeus dot com
  Target Milestone: ---

Hi,

The following snippet issues a wrong -Wdangling-reference warning when compiled
with -Wall with current gcc trunk:

<<END_OF_FILE
struct A {};

struct B
{
    B(int) {}
};

const A& f(const A& a, const B&) {
    return a;
}

const A& g(const A& a) {
    const A& result = f(a, 42);

    return result;
}
END_OF_FILE

The warning is:

<source>: In function 'const A& g(const A&)':
<source>:13:14: warning: possibly dangling reference to a temporary
[-Wdangling-reference]
   13 |     const A& result = f(a, 42);
      |              ^~~~~~
<source>:13:24: note: the temporary was destroyed at the end of the full
expression 'f((* & a), B(42))'
   13 |     const A& result = f(a, 42);
      |                       ~^~~~~~~
ASM generation compiler returned: 0
<source>: In function 'const A& g(const A&)':
<source>:13:14: warning: possibly dangling reference to a temporary
[-Wdangling-reference]
   13 |     const A& result = f(a, 42);
      |              ^~~~~~
<source>:13:24: note: the temporary was destroyed at the end of the full
expression 'f((* & a), B(42))'
   13 |     const A& result = f(a, 42);
      |                       ~^~~~~~~