unused-parameter compiler warnings

[alexandertuna]

Hello yall! @pnikiel

I'm doing some cleanup, and I noticed open62541-compat has 159 unused parameter compiler warnings. Would you mind if I submitted a MR for those? Or would you prefer to do it yourselves?

List: www.cern.ch/tuna/log_2021_11_19_15h11m29s.txt

[pnikiel]

Hi,
it depends what do you propose to do?
BTW could you remove duplicates from your list? There seems to be plenty of them.

[alexandertuna]

Oh yes, good point.

Update: www.cern.ch/tuna/log_2021_11_19_15h11m30s.txt

[tuna@afs] sort ~/www/log_2021_11_19_15h11m29s.txt | wc -l
159
[tuna@afs] sort ~/www/log_2021_11_19_15h11m29s.txt | uniq | wc -l
57

[pnikiel]

So, please tell me what is your idea of dealing with them?

[alexandertuna]

I'd suggest removing the variable name from the function definition/declaration, and not changing the function signature. That's how the internet has taught me to deal with compiler warnings when I don't actually want to change the contents of the function or change how people call the function. (I assume this is your perspective too: no changes)

Then there are two approaches to removing the variable name: the more verbose way and the less verbose way.

If I take this one as example:

open62541-compat/include/opcua_baseobjecttype.h:58:27: warning: unused parameter 'callback' [-Wunused-parameter]

The original:

	virtual UaStatus beginCall (
			MethodManagerCallback *callback,
			const ServiceContext  &context,
			OpcUa_UInt32          callbackHandle,
			MethodHandle          *methodHandle,
			const UaVariantArray  &inputArguments) { return OpcUa_Bad; }

The more verbose approach (keeps the unused variable name around):

	virtual UaStatus beginCall (
			MethodManagerCallback * /* callback */,
			const ServiceContext  &context,
			OpcUa_UInt32          callbackHandle,
			MethodHandle          *methodHandle,
			const UaVariantArray  &inputArguments) { return OpcUa_Bad; }

The less verbose approach (doesn't keep the unused variable name):

	virtual UaStatus beginCall (
			MethodManagerCallback *,
			const ServiceContext  &context,
			OpcUa_UInt32          callbackHandle,
			MethodHandle          *methodHandle,
			const UaVariantArray  &inputArguments) { return OpcUa_Bad; }

The effect is the same for both

[pnikiel]

Hang tight, we're processing your request. In the meantime Ben proposed to propose yet another way of using some macro.

[pnikiel]

Hi @alexandertuna ,

we discussed this internally and upon @ben-farnham proposal we'd prefer the following plan:
0. Make a ticket in JIRA (OPCUA project, component open62541-compat)

1. Get yourself a branch that starts with OPCUA-XXX_YYY (XXX to match the ticket number from 0, YYY to be some optional description text)
2. #define OPEN62541_COMPAT_UNUSED_PARAM(x) (void)(x) in include/open62541_compat.h
3. use this macro in the fnc/method bodies, where applicable, preferably at the top of a body. ( ;-) )
4. test it yourself,
5. propose a MR (assignee: me)

sounds ok?

[alexandertuna]

Hi @pnikiel and @ben-farnham , thanks for considering this and counter-proposing!

Do you prefer I make a JIRA ticket now, and stop commenting on github?

[alexandertuna]

Hm I think the answer must be "yes", since that is step 0 of the plan, so I'm doing that now.