[Geany-devel] [PATCH 2/3] Prevent -Wmissing-prototypes report warning when compiling a plugin

[Lex Trotman]

On 13 June 2010 03:46, Jiří Techet <techet at gmail.com> wrote:
> 2010/6/12 Enrico Tröger <enrico.troeger at uvena.de>:
>> On Thu, 10 Jun 2010 13:33:44 +0200, Jiří wrote:
>>
>>> On Thu, Jun 10, 2010 at 13:05, Nick Treleaven
>>> <nick.treleaven at btinternet.com> wrote:
>>> > On Wed,  9 Jun 2010 21:40:58 +0200
>>> > Jiří Techet <techet at gmail.com> wrote:
>>> >
>>> >> Signed-off-by: Jiří Techet <techet at gmail.com>
>>> >> ---
>>> >>  src/plugindata.h |    2 ++
>>> >
>>> >> +     gint plugin_version_check(gint abi_ver);\
>>> >>       gint plugin_version_check(gint abi_ver) \
>>> >>       { \
>>> >
>>> > Why is this necessary?
>>> >
>>>
>>> If you don't compile the plugins with -Wmissing-prototypes then you
>>> don't get any warnings if you use a function that hasn't been
>>> declared (imagine you make a typo in a call of an API function or any
>>> of your internal functions). The plugin compiles just fine, but then
>>> it doesn't get loaded by geany on runtime and you have to start
>>> searching for what symbol is missing (using LD_DEBUG).
>>>
>>> -Wmissing-prototypes requires that for every non-static function there
>>> is a previous declaration before it is defined/used. This is normally
>>> satisfied because these are in the header files - this macro is just
>>> an exceptional case.
>>>
>>> In general, I would recommend that geany uses a slightly more strict
>>> set of warning options. I find the options used by gnome-common as a
>>> reasonable set:
>>>
>>> -Wall -Wmissing-prototypes -Wnested-externs -Wpointer-arith
>>> -Wno-sign-compare
>>>
>>> You might consider using them for the whole geany.
>>
>> Just as an additional note:
>> compiler flags should always be used by individual developers/users,
>> not by the used build system directly.
>
> Why? If you want to ensure that the sources satisfy some standards,
> then it's alright. You use -Wall after all.
>
>> -Wmissing-prototypes and friends are gcc specific and would break
>> building with other compilers.
>>
>> I guess you didn't mean to add them to the build system directly :).
>
> You can use gnome-compiler-flags.m4 from the gnome-common package that
> checks whether you use gcc for compilation and only in this case the
> above flags are added (it adds a configure parameter where the set of
> flags can be configured).
>
> Regards,
>
> Jiri

I think its worth putting the prototypes in the header as Nick
suggests even without this being a standard build flag. Then if the
prototype even did have to change or, heaven forbid, the plugin writer
makes a mistake, the compiler has a chance of warning you.

Then you only need -Wmissing-prototypes occasionally to check for
"dangling functions".

Cheers
Lex


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