On Fri, Oct 2, 2020 at 9:21 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
>
> I do care about the tree as a whole, and I'm particularly interested in
> having -Wmissing-declarations/-Wmissing-prototypes enabled globally
> at some point in the future.
>
> Arnd
BTW, if possible, please educate me about the difference
between -Wmissing-declarations and -Wmissing-prototypes.
The GCC manual says as follows:
-Wmissing-prototypes (C and Objective-C only)
Warn if a global function is defined without a previous prototype
declaration. This warning is issued even if the definition itself
provides a prototype. Use this option to detect global functions that
do not have a matching prototype declaration in a header file. This
option is not valid for C++ because all function declarations provide
prototypes and a non-matching declaration declares an overload rather
than conflict with an earlier declaration. Use -Wmissing-declarations
to detect missing declarations in C++.
-Wmissing-declarations
Warn if a global function is defined without a previous declaration.
Do so even if the definition itself provides a prototype. Use this
option to detect global functions that are not declared in header
files. In C, no warnings are issued for functions with previous
non-prototype declarations; use -Wmissing-prototypes to detect missing
prototypes. In C++, no warnings are issued for function templates, or
for inline functions, or for functions in anonymous namespaces.
The difference is still unclear to me...
For example, if I add -Wmissing-declarations, I get the following:
kernel/sched/core.c:2380:6: warning: no previous declaration for
‘sched_set_stop_task’ [-Wmissing-declarations]
2380 | void sched_set_stop_task(int cpu, struct task_struct *stop)
| ^~~~~~~~~~~~~~~~~~~
But, if I add both -Wmissing-declarations and -Wmissing-prototypes,
-Wmissing-declarations is superseded by -Wmissing-prototypes.
kernel/sched/core.c:2380:6: warning: no previous prototype for
‘sched_set_stop_task’ [-Wmissing-prototypes]
2380 | void sched_set_stop_task(int cpu, struct task_struct *stop)
| ^~~~~~~~~~~~~~~~~~~
Do we need to specify both in W=1 ?
If yes, what is the difference between them?
--
Best Regards
Masahiro Yamada
