https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63181
Eric Gallager <egallager at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |egallager at gcc dot gnu.org
Blocks| |87403, 7651
--- Comment #4 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Brooks Moses from comment #0)
> GCC should warn about "obvious" bugs in binding a reference to temporary.
>
> Small test case:
>
> struct Foo {
> Foo(int x): x_(x) { }
> int& x_;
> };
>
>
> int main()
> {
> Foo f(0);
> return f.x_;
> }
>
> Gcc -Wall is silent.
>
>
> Clang detects this clearly:
> clang++ foo.cc -Wall
> foo.cc:2:19: warning: binding reference member 'x_' to stack allocated
> parameter 'x' [-Wdangling-field]
> Foo(int x): x_(x) { }
> ^
> foo.cc:3:9: note: reference member declared here
> int& x_;
> ^
> 1 warning generated.
If we reuse clang's -Wdangling-field name, this would be a new warning, so
making it block the relevant meta-bug.
(In reply to Jonathan Wakely from comment #2)
> N.B. that's not a temporary, it's a named lvalue, but we should definitely
> diagnose it.
>
> Since 4.7 GCC does now diagnose similar cases with temporaries resulting
> from implicit conversions:
>
> struct Foo {
> Foo(short x): x_(x) { }
> const int& x_;
> };
>
> int main()
> {
> Foo f(0);
> return f.x_;
> }
>
> t.cc: In constructor ‘Foo::Foo(short int)’:
> t.cc:2:22: warning: a temporary bound to ‘Foo::x_’ only persists until the
> constructor exits [-Wextra]
> Foo(short x): x_(x) { }
> ^
This one should be moved to its own separate option per bug 7651
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=7651
[Bug 7651] Define -Wextra strictly in terms of other warning flags
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87403
[Bug 87403] [Meta-bug] Issues that suggest a new warning
