[Bug c++/63181] GCC should warn about "obvious" bugs in binding a reference to temporary

2019-11-21 Thread redi at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63181

--- Comment #5 from Jonathan Wakely  ---
(In reply to Eric Gallager from comment #4)
> This one should be moved to its own separate option per bug 7651

Indeed it should, and if we add -Wdangling-field then that would be the ideal
option to move it to.

[Bug c++/63181] GCC should warn about "obvious" bugs in binding a reference to temporary

2019-11-21 Thread egallager at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63181

Eric Gallager  changed:

   What|Removed |Added

 CC||egallager at gcc dot gnu.org
 Blocks||87403, 7651

--- Comment #4 from Eric Gallager  ---
(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

[Bug c++/63181] GCC should warn about obvious bugs in binding a reference to temporary

2014-10-20 Thread redi at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63181

Jonathan Wakely redi at gcc dot gnu.org changed:

   What|Removed |Added

 CC||bcmpinc at hotmail dot com

--- Comment #3 from Jonathan Wakely redi at gcc dot gnu.org ---
*** Bug 63606 has been marked as a duplicate of this bug. ***

[Bug c++/63181] GCC should warn about obvious bugs in binding a reference to temporary

2014-09-05 Thread rguenth at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63181

Richard Biener rguenth at gcc dot gnu.org changed:

   What|Removed |Added

   Keywords||diagnostic
 Status|UNCONFIRMED |NEW
   Last reconfirmed||2014-09-05
 Ever confirmed|0   |1
   Severity|minor   |enhancement

--- Comment #1 from Richard Biener rguenth at gcc dot gnu.org ---
Confirmed.

[Bug c++/63181] GCC should warn about obvious bugs in binding a reference to temporary

2014-09-05 Thread redi at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63181

--- Comment #2 from Jonathan Wakely redi at gcc dot gnu.org ---
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) { }
  ^