https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110213
Bug ID: 110213
Summary: Bogus (as opposed to false positive)
-Wdangling-reference warning
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: boris at kolpackov dot net
Target Milestone: ---
I have a call that, AFAICS, doesn't involve any binding of references to
temporaries but which nevertheless still produces this warning. The code boils
down to the following:
const target& search (const target&, name);
void pattern::apply(target& t) const
{
name n = ...;
const target& p (search (t, std::move (n))); // <- Warning points here.
}
However, I was not able to reduce it to a small reproducer so it seems to
depend on the overall context. So I am attaching a partially preprocessed TU.
To reproduce, run:
$ g++ -std=c++23 -Wall -Wextra -fdirectives-only -c adhoc-rule-regex-pattern.ii
adhoc-rule-regex-pattern.cxx: In member function ‘virtual void
build2::adhoc_rule_regex_pattern::apply_prerequisites(build2::action,
build2::target&, const scope&, build2::match_extra&) const’:
adhoc-rule-regex-pattern.cxx:485:21: warning: possibly dangling reference to a
temporary [-Wdangling-reference]
485 | const target& pt (search (t, move (n), *s, &e.type));
| ^~
adhoc-rule-regex-pattern.cxx:485:32: note: the temporary was destroyed at the
end of the full expression
‘build2::search((*(const build2::target*)(& t)), build2::name((* &
std::move<build2::name&>(n))), (* s), (&
e.build2::adhoc_rule_regex_pattern::element::type))’
485 | const target& pt (search (t, move (n), *s, &e.type));
| ~~~~~~~^~
The last two arguments (*s, &e.type) in the call do not make any difference.
Changing the search() function to take name by const& or && makes the warning
disappear.
$ g++ --version
g++-13 (Debian 13.1.0-3) 13.1.0
