error: this member function can be declared static [loplugin:staticmethods] when adding a event function in a dialog

[Caolán McNamara]

On Fri, 2024-03-29 at 09:07 +0100, Heiko Tietze wrote:
> On 28.03.24 6:09 PM, Caolán McNamara wrote:
> > On Fri, 2024-03-29 at 00:16 +0800, Sakura286 wrote:
> > > 
> > > https://gerrit.libreoffice.org/c/core/+/165391
> > 
> > You might want DECL_STATIC_LINK instead of DECL_LINK. The matching
> > IMPL_LINK then needs to be IMPL_STATIC_LINK etc.
> 
> Curious to learn why this needs to be static. What makes the one
> button different from the other?

Nothing special about the button itself, it's the content of the
function that has triggered the warning. The plugin has just detected
that the function doesn't actually use anything from an instance of the
class it is a member of, so the function could be static, not need the
implicit "this" passed as an argument which frees up a register and can
potentially be that tiny little bit more optimized. And/or make it
clearer to the reader that calling it will only have an effect on the
passed-in arg and not an effect on any specific object. These are our
own clang plugins, so this isn't a C++ requirement of any kind, just
our extra stylistic rules.

Taking
https://cgit.freedesktop.org/libreoffice/core/tree/sfx2/source/appl/sfxhelp.cxx#n91
if HelpRequestHdl did something like
m_xErrBox->set_primary_text("hello world")
then HelpRequestHdl couldn't be a static and we would use DECL_LINK and
IMPL_LINK instead, and
m_xErrBox->connect_help(LINK(nullptr, NoHelpErrorBox, HelpRequestHdl));
would instead have to be
m_xErrBox->connect_help(LINK(this, NoHelpErrorBox, HelpRequestHdl));

and vice versa if the code was like this already, and someone dropped
the m_xErrBox->set_primary_text("hello world") line then the plugin
would begin to warn that it could be static instead