[Bug c++/114220] False positive warning: possibly dangling reference to a temporary [-Wdangling-reference]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114220 Xi Ruoyao changed: What|Removed |Added CC||asharafutdinov at adalisk dot com --- Comment #5 from Xi Ruoyao --- *** Bug 114225 has been marked as a duplicate of this bug. ***
[Bug c++/114220] False positive warning: possibly dangling reference to a temporary [-Wdangling-reference]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114220
--- Comment #4 from Andrew Pinski ---
(In reply to Дилян Палаузов from comment #3)
> > The warning is designed this way explictly because you are returning a
> > reference and taking a reference as an argument and in the case of b2, the
> > tempory is `std::string("u")` .
>
> > In GCC 14+ (since r14-9263-gc7607c4cf18986), you can add
> > [[gnu::no_dangling]] to the z2 function definition to mark it as not
> > returning a dangling reference (from the arguments). and the warning goes
> > away.
>
> If the declaration and definitions are in different files, do I have to add
> [[gnu::no_dangling]] only to the function declaration ?
Yes only on the declaration is needed.
>
> That said, is the warning triggered only based on the function declaration
> (accepting as parameter a reference to temporary and returning a reference),
> when on the function invocation the parameter is indeed a reference to a
> temporary?
Yes that is correct, it is based on the function declaration only and the
warning does not look into the function to see it does not return the a
referenced based on the reference being passed.
[Bug c++/114220] False positive warning: possibly dangling reference to a temporary [-Wdangling-reference]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114220
--- Comment #3 from Дилян Палаузов ---
> The warning is designed this way explictly because you are returning a
> reference and taking a reference as an argument and in the case of b2, the
> tempory is `std::string("u")` .
> In GCC 14+ (since r14-9263-gc7607c4cf18986), you can add [[gnu::no_dangling]]
> to the z2 function definition to mark it as not returning a dangling
> reference (from the arguments). and the warning goes away.
If the declaration and definitions are in different files, do I have to add
[[gnu::no_dangling]] only to the function declaration ?
That said, is the warning triggered only based on the function declaration
(accepting as parameter a reference to temporary and returning a reference),
when on the function invocation the parameter is indeed a reference to a
temporary?
[Bug c++/114220] False positive warning: possibly dangling reference to a temporary [-Wdangling-reference]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114220 --- Comment #2 from Дилян Палаузов --- Is my reading correct, that the warning is triggered, when a function receives as parameter a reference to a temporary and returns a reference? If this is the only criterion, then it is a wrong assumption, that both references are somehow related.
[Bug c++/114220] False positive warning: possibly dangling reference to a temporary [-Wdangling-reference]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114220
Andrew Pinski changed:
What|Removed |Added
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #1 from Andrew Pinski ---
const std::string& z2(const std::string& m);
const std::string& z2(const std::string& m) { return hashTable2.at(m); }
const std::string& b2 { z2("u") };
The warning is designed this way explictly because you are returning a
reference and taking a reference as an argument and in the case of b2, the
tempory is `std::string("u")` .
In GCC 14+ (since r14-9263-gc7607c4cf18986), you can add [[gnu::no_dangling]]
to the z2 function definition to mark it as not returning a dangling reference
(from the arguments). and the warning goes away.
