Wandbox

Ran/Viewed Log

Author

anonymous

over 6 years ago

Language

C++

Compiler

gcc HEAD 9.0.0 20180630 (experimental)

Options

Warnings

Boost 1.67.0

C++2a(GNU)

no pedantic

Author

anonymous

over 6 years ago

$ g++ prog.cc -Wall -Wextra -I/opt/wandbox/boost-1.67.0/gcc-head/include -std=gnu++2a

prog.cc: In function 'void bad_foo()':
prog.cc:47:38: warning: ignoring returned value of type 'ResetGuard<int>', declared with attribute nodiscard [-Wunused-result]
     temporarily_set_global_value (15);
                                      ^
prog.cc:40:17: note: in call to 'ResetGuard<int> temporarily_set_global_value(int)', declared here
 ResetGuard<int> temporarily_set_global_value (int new_val)
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.cc:6:40: note: 'ResetGuard<int>' declared here
 template <class T> class [[nodiscard]] ResetGuard
                                        ^~~~~~~~~~
GLOBAL_VALUE in bad_foo () is 0
GLOBAL_VALUE in good_foo () is 15
GLOBAL_VALUE after good_foo () returns is 0
GLOBAL_VALUE in better_foo () is 15
GLOBAL_VALUE after better_foo () returns is 15
GLOBAL_VALUE after ResetGuard moved is 15
GLOBAL_VALUE after ResetGuard moved to goes out of scope is 0
GLOBAL_VALUE after ResetGuard moved from goes out of scope is 42

Exit Code:

0